Author name code: mclaughlin ADS astronomy entries on 2022-09-14 author:"McLaughlin, James A." ------------------------------------------------------------------------ Title: Observations of Instability-driven Nanojets in Coronal Loops Authors: Sukarmadji, A. Ramada C.; Antolin, Patrick; McLaughlin, James A. Bibcode: 2022ApJ...934..190S Altcode: 2022arXiv220210960S The recent discovery of nanojets by Antolin et al. represents magnetic reconnection in a braided field, thus clearly identifying reconnection-driven nanoflares. Due to their small scale (500 km in width, 1500 km in length) and short timescales (<15 s), it is unclear how pervasive nanojets are in the solar corona. In this paper, we present Interface Region Imaging Spectrograph and Solar Dynamics Observatory observations of nanojets found in multiple coronal structures, namely, in a coronal loop powered by a blowout jet, and in two other coronal loops with coronal rain. In agreement with previous findings, we observe that nanojets are accompanied by small nanoflare-like intensity bursts in the (E)UV, have velocities of 150-250 km s-1 and occur transversely to the field line of origin, which is sometimes observed to split. However, we find a variety of nanojet directions in the plane transverse to the loop axis. These nanojets are found to have kinetic and thermal energies within the nanoflare range, and often occur in clusters. In the blowout jet case study, the Kelvin-Helmholtz instability (KHI) is directly identified as the reconnection driver. For the other two loops, we find that both, KHI and Rayleigh-Taylor instability (RTI) are likely to be the drivers. However, we find that KHI and RTI are each more likely in one of the other two cases. These observations of nanojets in a variety of structures and environments support nanojets being a general result of reconnection that are driven here by dynamic instabilities. Title: The Independence of Oscillatory Reconnection Periodicity from the Initial Pulse Authors: Karampelas, Konstantinos; McLaughlin, James A.; Botha, Gert J. J.; Régnier, Stéphane Bibcode: 2022ApJ...933..142K Altcode: 2022arXiv220701980K Oscillatory reconnection can manifest through the interaction between the ubiquitous MHD waves and omnipresent null points in the solar atmosphere and is characterized by an inherent periodicity. In the current study, we focus on the relationship between the period of oscillatory reconnection and the strength of the wave pulse initially perturbing the null point, in a hot coronal plasma. We use the PLUTO code to solve the fully compressive, resistive MHD equations for a 2D magnetic X-point. Using wave pulses with a wide range of amplitudes, we perform a parameter study to obtain values for the period, considering the presence and absence of anisotropic thermal conduction separately. In both cases, we find that the resulting period is independent of the strength of the initial perturbation. The addition of anisotropic thermal conduction only leads to an increase in the mean value for the period, in agreement with our previous study. We also consider a different type of initial driver and we obtain an oscillation period matching the independent trend previously mentioned. Thus, we report for the first time on the independence between the type and strength of the initializing wave pulse and the resulting period of oscillatory reconnection in a hot coronal plasma. This makes oscillatory reconnection a promising mechanism to be used within the context of coronal seismology. Title: Oscillatory Reconnection of a 2D X-point in a hot coronal plasma Authors: Karampelas, Konstantinos; Botha, Gert J. J.; Regnier, Stephane; Mclaughlin, James A. Bibcode: 2022cosp...44.2559K Altcode: Oscillatory reconnection (a relaxation mechanism with periodic changes in connectivity) has been proposed as a potential physical mechanism underpinning several periodic phenomena in the solar atmosphere including, but not limited to, quasi-periodic pulsations (QPPs) and flows. In the past, this mechanism had been extensively studied numerically for 2D and 3D simulations of null points in cold plasma. In our latest studies, we have expanded our understanding of oscillatory reconnection, by considering for the first time hot, coronal plasma. We will be presenting our latest results, from numerically solving the fully-compressive, resistive MHD equations for a 2D magnetic X-point under coronal conditions using the PLUTO code. We report on the resulting oscillatory reconnection including its periodicity and decay rate, by tracking the evolution of the current density profile at the null point. We also consider, for the first time, the effect of adding anisotropic thermal conduction to the mechanism, and how it simplifies the spectrum of the oscillation profile and increases its decay rate, while still allowing the mechanism to manifest. Finally, we reveal how the equilibrium magnetic field strength, density distribution and the amplitude of the initial perturbation relate to the decay rate, and period of oscillatory reconnection, opening the tantalising possibility of utilizing oscillatory reconnection as a seismological tool. Title: Using Oscillatory Reconnection of a 2D X-point as a tool for coronal seismology. Authors: Karampelas, Konstantinos; Botha, Gert J. J.; Regnier, Stephane; Mclaughlin, James A. Bibcode: 2022cosp...44.2487K Altcode: The mechanism of oscillatory reconnection of a null point has been one of the proposed mechanisms behind phenomena like quasi-periodic pulsations (QPPs). The manifestation of this mechanism through the interaction of the ubiquitous waves with null points in the solar atmosphere opens the possibility of utilizing oscillatory reconnection as a tool for coronal seismology. In the past, the first steps had been taken, by connecting the length of the initial current sheet with the period of oscillatory reconnection, and by identifying a linear regime where the period is affected by resistivity. Our recent numerical studies have expanded upon these findings, by considering plasma at coronal conditions, with the addition of anisotropic thermal conduction. We have performed a series of parameter studies with the use of the PLUTO code, which reveal a relation between the equilibrium magnetic field strength and density distribution with the period and decay rate of oscillatory reconnection. In addition, we see an independence of the oscillation period from the type and strength of the external wave pulse, which perturbs the null from its initial equilibrium state. This allows us to formulate an empirical formula connecting these four quantities, opening the way in using oscillatory reconnection for coronal seismology. Title: First Dark Matter Search Results from the LUX-ZEPLIN (LZ) Experiment Authors: Aalbers, J.; Akerib, D. S.; Akerlof, C. W.; Al Musalhi, A. K.; Alder, F.; Alqahtani, A.; Alsum, S. K.; Amarasinghe, C. S.; Ames, A.; Anderson, T. J.; Angelides, N.; Araújo, H. M.; Armstrong, J. E.; Arthurs, M.; Azadi, S.; Bailey, A. J.; Baker, A.; Balajthy, J.; Balashov, S.; Bang, J.; Bargemann, J. W.; Barry, M. J.; Barthel, J.; Bauer, D.; Baxter, A.; Beattie, K.; Belle, J.; Beltrame, P.; Bensinger, J.; Benson, T.; Bernard, E. P.; Bhatti, A.; Biekert, A.; Biesiadzinski, T. P.; Birch, H. J.; Birrittella, B.; Blockinger, G. M.; Boast, K. E.; Boxer, B.; Bramante, R.; Brew, C. A. J.; Brás, P.; Buckley, J. H.; Bugaev, V. V.; Burdin, S.; Busenitz, J. K.; Buuck, M.; Cabrita, R.; Carels, C.; Carlsmith, D. L.; Carlson, B.; Carmona-Benitez, M. C.; Cascella, M.; Chan, C.; Chawla, A.; Chen, H.; Cherwinka, J. J.; Chott, N. I.; Cole, A.; Coleman, J.; Converse, M. V.; Cottle, A.; Cox, G.; Craddock, W. W.; Creaner, O.; Curran, D.; Currie, A.; Cutter, J. E.; Dahl, C. E.; David, A.; Davis, J.; Davison, T. J. R.; Delgaudio, J.; Dey, S.; de Viveiros, L.; Dobi, A.; Dobson, J. E. Y.; Druszkiewicz, E.; Dushkin, A.; Edberg, T. K.; Edwards, W. R.; Elnimr, M. M.; Emmet, W. T.; Eriksen, S. R.; Faham, C. H.; Fan, A.; Fayer, S.; Fearon, N. M.; Fiorucci, S.; Flaecher, H.; Ford, P.; Francis, V. B.; Fraser, E. D.; Fruth, T.; Gaitskell, R. J.; Gantos, N. J.; Garcia, D.; Geffre, A.; Gehman, V. M.; Genovesi, J.; Ghag, C.; Gibbons, R.; Gibson, E.; Gilchriese, M. G. D.; Gokhale, S.; Gomber, B.; Green, J.; Greenall, A.; Greenwood, S.; van der Grinten, M. G. D.; Gwilliam, C. B.; Hall, C. R.; Hans, S.; Hanzel, K.; Harrison, A.; Hartigan-O'Connor, E.; Haselschwardt, S. J.; Hertel, S. A.; Heuermann, G.; Hjemfelt, C.; Hoff, M. D.; Holtom, E.; Y-K. Hor, J.; Horn, M.; Huang, D. Q.; Hunt, D.; Ignarra, C. M.; Jacobsen, R. G.; Jahangir, O.; James, R. S.; Jeffery, S. N.; Ji, W.; Johnson, J.; Kaboth, A. C.; Kamaha, A. C.; Kamdin, K.; Kasey, V.; Kazkaz, K.; Keefner, J.; Khaitan, D.; Khaleeq, M.; Khazov, A.; Khurana, I.; Kim, Y. D.; Kocher, C. D.; Kodroff, D.; Korley, L.; Korolkova, E. V.; Kras, J.; Kraus, H.; Kravitz, S.; Krebs, H. J.; Kreczko, L.; Krikler, B.; Kudryavtsev, V. A.; Kyre, S.; Landerud, B.; Leason, E. A.; Lee, C.; Lee, J.; Leonard, D. S.; Leonard, R.; Lesko, K. T.; Levy, C.; Li, J.; Liao, F. -T.; Liao, J.; Lin, J.; Lindote, A.; Linehan, R.; Lippincott, W. H.; Liu, R.; Liu, X.; Liu, Y.; Loniewski, C.; Lopes, M. I.; Lopez Asamar, E.; López Paredes, B.; Lorenzon, W.; Lucero, D.; Luitz, S.; Lyle, J. M.; Majewski, P. A.; Makkinje, J.; Malling, D. C.; Manalaysay, A.; Manenti, L.; Mannino, R. L.; Marangou, N.; Marzioni, M. F.; Maupin, C.; McCarthy, M. E.; McConnell, C. T.; McKinsey, D. N.; McLaughlin, J.; Meng, Y.; Migneault, J.; Miller, E. H.; Mizrachi, E.; Mock, J. A.; Monte, A.; Monzani, M. E.; Morad, J. A.; Morales Mendoza, J. D.; Morrison, E.; Mount, B. J.; Murdy, M.; Murphy, A. St. J.; Naim, D.; Naylor, A.; Nedlik, C.; Nehrkorn, C.; Nelson, H. N.; Neves, F.; Nguyen, A.; Nikoleyczik, J. A.; Nilima, A.; O'Dell, J.; O'Neill, F. G.; O'Sullivan, K.; Olcina, I.; Olevitch, M. A.; Oliver-Mallory, K. C.; Orpwood, J.; Pagenkopf, D.; Pal, S.; Palladino, K. J.; Palmer, J.; Pangilinan, M.; Parveen, N.; Patton, S. J.; Pease, E. K.; Penning, B.; Pereira, C.; Pereira, G.; Perry, E.; Pershing, T.; Peterson, I. B.; Piepke, A.; Podczerwinski, J.; Porzio, D.; Powell, S.; Preece, R. M.; Pushkin, K.; Qie, Y.; Ratcliff, B. N.; Reichenbacher, J.; Reichhart, L.; Rhyne, C. A.; Richards, A.; Riffard, Q.; Rischbieter, G. R. C.; Rodrigues, J. P.; Rodriguez, A.; Rose, H. J.; Rosero, R.; Rossiter, P.; Rushton, T.; Rutherford, G.; Rynders, D.; Saba, J. S.; Santone, D.; Sazzad, A. B. M. R.; Schnee, R. W.; Scovell, P. R.; Seymour, D.; Shaw, S.; Shutt, T.; Silk, J. J.; Silva, C.; Sinev, G.; Skarpaas, K.; Skulski, W.; Smith, R.; Solmaz, M.; Solovov, V. N.; Sorensen, P.; Soria, J.; Stancu, I.; Stark, M. R.; Stevens, A.; Stiegler, T. M.; Stifter, K.; Studley, R.; Suerfu, B.; Sumner, T. J.; Sutcliffe, P.; Swanson, N.; Szydagis, M.; Tan, M.; Taylor, D. J.; Taylor, R.; Taylor, W. C.; Temples, D. J.; Tennyson, B. P.; Terman, P. A.; Thomas, K. J.; Tiedt, D. R.; Timalsina, M.; To, W. H.; Tomás, A.; Tong, Z.; Tovey, D. R.; Tranter, J.; Trask, M.; Tripathi, M.; Tronstad, D. R.; Tull, C. E.; Turner, W.; Tvrznikova, L.; Utku, U.; Va'vra, J.; Vacheret, A.; Vaitkus, A. C.; Verbus, J. R.; Voirin, E.; Waldron, W. L.; Wang, A.; Wang, B.; Wang, J. J.; Wang, W.; Wang, Y.; Watson, J. R.; Webb, R. C.; White, A.; White, D. T.; White, J. T.; White, R. G.; Whitis, T. J.; Williams, M.; Wisniewski, W. J.; Witherell, M. S.; Wolfs, F. L. H.; Wolfs, J. D.; Woodford, S.; Woodward, D.; Worm, S. D.; Wright, C. J.; Xia, Q.; Xiang, X.; Xiao, Q.; Xu, J.; Yeh, M.; Yin, J.; Young, I.; Zarzhitsky, P.; Zuckerman, A.; Zweig, E. A. Bibcode: 2022arXiv220703764A Altcode: The LUX-ZEPLIN (LZ) experiment is a dark matter detector centered on a dual-phase xenon time projection chamber operating at the Sanford Underground Research Facility in Lead, South Dakota, USA. This Letter reports results from LZ's first search for Weakly Interacting Massive Particles (WIMPs) with an exposure of 60 live days using a fiducial mass of 5.5 t. A profile-likelihood ratio analysis shows the data to be consistent with a background-only hypothesis, setting new limits on spin-independent WIMP-nucleon, spin-dependent WIMP-neutron, and spin-dependent WIMP-proton cross-sections for WIMP masses above 9 GeV/c$^2$. The most stringent limit is set at 30 GeV/c$^2$, excluding cross sections above 5.9$\times 10^{-48}$ cm$^2$ at the 90\% confidence level. Title: Cosmogenic production of 37Ar in the context of the LUX-ZEPLIN experiment Authors: Aalbers, J.; Akerib, D. S.; Al Musalhi, A. K.; Alder, F.; Alsum, S. K.; Amarasinghe, C. S.; Ames, A.; Anderson, T. J.; Angelides, N.; Araújo, H. M.; Armstrong, J. E.; Arthurs, M.; Bai, X.; Baker, A.; Balajthy, J.; Balashov, S.; Bang, J.; Bargemann, J. W.; Bauer, D.; Baxter, A.; Beattie, K.; Bernard, E. P.; Bhatti, A.; Biekert, A.; Biesiadzinski, T. P.; Birch, H. J.; Blockinger, G. M.; Bodnia, E.; Boxer, B.; Brew, C. A. J.; Brás, P.; Burdin, S.; Busenitz, J. K.; Buuck, M.; Cabrita, R.; Carmona-Benitez, M. C.; Cascella, M.; Chan, C.; Chawla, A.; Chen, H.; Chott, N. I.; Cole, A.; Converse, M. V.; Cottle, A.; Cox, G.; Creaner, O.; Cutter, J. E.; Dahl, C. E.; David, A.; de Viveiros, L.; Dobson, J. E. Y.; Druszkiewicz, E.; Eriksen, S. R.; Fan, A.; Fayer, S.; Fearon, N. M.; Fiorucci, S.; Flaecher, H.; Fraser, E. D.; Fruth, T.; Gaitskell, R. J.; Genovesi, J.; Ghag, C.; Gibson, E.; Gilchriese, M. G. D.; Gokhale, S.; van der Grinten, M. G. D.; Gwilliam, C. B.; Hall, C. R.; Haselschwardt, S. J.; Hertel, S. A.; Horn, M.; Huang, D. Q.; Hunt, D.; Ignarra, C. M.; Jahangir, O.; James, R. S.; Ji, W.; Johnson, J.; Kaboth, A. C.; Kamaha, A. C.; Kamdin, K.; Khaitan, D.; Khazov, A.; Khurana, I.; Kodroff, D.; Korley, L.; Korolkova, E. V.; Kraus, H.; Kravitz, S.; Kreczko, L.; Kudryavtsev, V. A.; Leason, E. A.; Leonard, D. S.; Lesko, K. T.; Levy, C.; Lee, J.; Lin, J.; Lindote, A.; Linehan, R.; Lippincott, W. H.; Liu, X.; Lopes, M. I.; Lopez Asamar, E.; Lopez-Paredes, B.; Lorenzon, W.; Luitz, S.; Majewski, P. A.; Manalaysay, A.; Manenti, L.; Mannino, R. L.; Marangou, N.; McCarthy, M. E.; McKinsey, D. N.; McLaughlin, J.; Miller, E. H.; Mizrachi, E.; Monte, A.; Monzani, M. E.; Morad, J. A.; Morales Mendoza, J. D.; Morrison, E.; Mount, B. J.; Murphy, A. St. J.; Naim, D.; Naylor, A.; Nedlik, C.; Nelson, H. N.; Neves, F.; Nikoleyczik, J. A.; Nilima, A.; Olcina, I.; Oliver-Mallory, K.; Pal, S.; Palladino, K. J.; Palmer, J.; Parveen, N.; Patton, S. J.; Pease, E. K.; Penning, B.; Pereira, G.; Perry, E.; Pershing, J.; Piepke, A.; Porzio, D.; Qie, Y.; Reichenbacher, J.; Rhyne, C. A.; Richards, A.; Riffard, Q.; Rischbieter, G. R. C.; Rosero, R.; Rossiter, P.; Rushton, T.; Santone, D.; Sazzad, A. B. M. R.; Schnee, R. W.; Scovell, P. R.; Shaw, S.; Shutt, T. A.; Silk, J. J.; Silva, C.; Sinev, G.; Smith, R.; Solmaz, M.; Solovov, V. N.; Sorensen, P.; Soria, J.; Stancu, I.; Stevens, A.; Stifter, K.; Suerfu, B.; Sumner, T. J.; Swanson, N.; Szydagis, M.; Taylor, W. C.; Taylor, R.; Temples, D. J.; Terman, P. A.; Tiedt, D. R.; Timalsina, M.; To, W. H.; Tong, Z.; Tovey, D. R.; Trask, M.; Tripathi, M.; Tronstad, D. R.; Turner, W.; Utku, U.; Vaitkus, A.; Wang, B.; Wang, Y.; Wang, J. J.; Wang, W.; Watson, J. R.; Webb, R. C.; White, R. G.; Whitis, T. J.; Williams, M.; Wolfs, F. L. H.; Woodford, S.; Woodward, D.; Wright, C. J.; Xia, Q.; Xiang, X.; Xu, J.; Yeh, M.; Lux-Zeplin Collaboration Bibcode: 2022PhRvD.105h2004A Altcode: 2022arXiv220102858A We estimate the amount of 37Ar produced in natural xenon via cosmic-ray-induced spallation, an inevitable consequence of the transportation and storage of xenon on the Earth's surface. We then calculate the resulting 37Ar concentration in a 10-tonne payload (similar to that of the LUX-ZEPLIN experiment) assuming a representative schedule of xenon purification, storage, and delivery to the underground facility. Using the spallation model by Silberberg and Tsao, the sea-level production rate of 37Ar in natural xenon is estimated to be 0.024 atoms /kg /day . Assuming the xenon is successively purified to remove radioactive contaminants in 1-tonne batches at a rate of 1 tonne /month , the average 37Ar activity after 10 tons are purified and transported underground is 0.058 −0.090 μ Bq /kg , depending on the degree of argon removal during above-ground purification. Such cosmogenic 37Ar will appear as a noticeable background in the early science data, while decaying with a 35-day half-life. This newly noticed production mechanism of 37Ar should be considered when planning for future liquid-xenon-based experiments. Title: Novel Data Analysis Techniques in Coronal Seismology Authors: Anfinogentov, Sergey A.; Antolin, Patrick; Inglis, Andrew R.; Kolotkov, Dmitrii; Kupriyanova, Elena G.; McLaughlin, James A.; Nisticò, Giuseppe; Pascoe, David J.; Krishna Prasad, S.; Yuan, Ding Bibcode: 2022SSRv..218....9A Altcode: 2021arXiv211213577A We review novel data analysis techniques developed or adapted for the field of coronal seismology. We focus on methods from the last ten years that were developed for extreme ultraviolet (EUV) imaging observations of the solar corona, as well as for light curves from radio and X-ray. The review covers methods for the analysis of transverse and longitudinal waves; spectral analysis of oscillatory signals in time series; automated detection and processing of large data sets; empirical mode decomposition; motion magnification; and reliable detection, including the most common pitfalls causing artefacts and false detections. We also consider techniques for the detailed investigation of MHD waves and seismological inference of physical parameters of the coronal plasma, including restoration of the three-dimensional geometry of oscillating coronal loops, forward modelling and Bayesian parameter inference. Title: A Next-Generation Liquid Xenon Observatory for Dark Matter and Neutrino Physics Authors: Aalbers, J.; Abe, K.; Aerne, V.; Agostini, F.; Maouloud, S. Ahmed; Akerib, D. S.; Akimov, D. Yu.; Akshat, J.; Al Musalhi, A. K.; Alder, F.; Alsum, S. K.; Althueser, L.; Amarasinghe, C. S.; Amaro, F. D.; Ames, A.; Anderson, T. J.; Andrieu, B.; Angelides, N.; Angelino, E.; Angevaare, J.; Antochi, V. C.; Antón Martin, D.; Antunovic, B.; Aprile, E.; Araújo, H. M.; Armstrong, J. E.; Arneodo, F.; Arthurs, M.; Asadi, P.; Baek, S.; Bai, X.; Bajpai, D.; Baker, A.; Balajthy, J.; Balashov, S.; Balzer, M.; Bandyopadhyay, A.; Bang, J.; Barberio, E.; Bargemann, J. W.; Baudis, L.; Bauer, D.; Baur, D.; Baxter, A.; Baxter, A. L.; Bazyk, M.; Beattie, K.; Behrens, J.; Bell, N. F.; Bellagamba, L.; Beltrame, P.; Benabderrahmane, M.; Bernard, E. P.; Bertone, G. F.; Bhattacharjee, P.; Bhatti, A.; Biekert, A.; Biesiadzinski, T. P.; Binau, A. R.; Biondi, R.; Biondi, Y.; Birch, H. J.; Bishara, F.; Bismark, A.; Blanco, C.; Blockinger, G. M.; Bodnia, E.; Boehm, C.; Bolozdynya, A. I.; Bolton, P. D.; Bottaro, S.; Bourgeois, C.; Boxer, B.; Brás, P.; Breskin, A.; Breur, P. A.; Brew, C. A. J.; Brod, J.; Brookes, E.; Brown, A.; Brown, E.; Bruenner, S.; Bruno, G.; Budnik, R.; Bui, T. K.; Burdin, S.; Buse, S.; Busenitz, J. K.; Buttazzo, D.; Buuck, M.; Buzulutskov, A.; Cabrita, R.; Cai, C.; Cai, D.; Capelli, C.; Cardoso, J. M. R.; Carmona-Benitez, M. C.; Cascella, M.; Catena, R.; Chakraborty, S.; Chan, C.; Chang, S.; Chauvin, A.; Chawla, A.; Chen, H.; Chepel, V.; Chott, N. I.; Cichon, D.; Cimental Chavez, A.; Cimmino, B.; Clark, M.; Co, R. T.; Colijn, A. P.; Conrad, J.; Converse, M. V.; Costa, M.; Cottle, A.; Cox, G.; Creaner, O.; Cuenca Garcia, J. J.; Cussonneau, J. P.; Cutter, J. E.; Dahl, C. E.; D'Andrea, V.; David, A.; Decowski, M. P.; Dent, J. B.; Deppisch, F. F.; de Viveiros, L.; Di Gangi, P.; Di Giovanni, A.; Di Pede, S.; Dierle, J.; Diglio, S.; Dobson, J. E. Y.; Doerenkamp, M.; Douillet, D.; Drexlin, G.; Druszkiewicz, E.; Dunsky, D.; Eitel, K.; Elykov, A.; Emken, T.; Engel, R.; Eriksen, S. R.; Fairbairn, M.; Fan, A.; Fan, J. J.; Farrell, S. J.; Fayer, S.; Fearon, N. M.; Ferella, A.; Ferrari, C.; Fieguth, A.; Fieguth, A.; Fiorucci, S.; Fischer, H.; Flaecher, H.; Flierman, M.; Florek, T.; Foot, R.; Fox, P. J.; Franceschini, R.; Fraser, E. D.; Frenk, C. S.; Frohlich, S.; Fruth, T.; Fulgione, W.; Fuselli, C.; Gaemers, P.; Gaior, R.; Gaitskell, R. J.; Galloway, M.; Gao, F.; Garcia Garcia, I.; Genovesi, J.; Ghag, C.; Ghosh, S.; Gibson, E.; Gil, W.; Giovagnoli, D.; Girard, F.; Glade-Beucke, R.; Glück, F.; Gokhale, S.; de Gouvêa, A.; Gráf, L.; Grandi, L.; Grigat, J.; Grinstein, B.; van der Grinten, M. G. D.; Grössle, R.; Guan, H.; Guida, M.; Gumbsheimer, R.; Gwilliam, C. B.; Hall, C. R.; Hall, L. J.; Hammann, R.; Han, K.; Hannen, V.; Hansmann-Menzemer, S.; Harata, R.; Hardin, S. P.; Hardy, E.; Hardy, C. A.; Harigaya, K.; Harnik, R.; Haselschwardt, S. J.; Hernandez, M.; Hertel, S. A.; Higuera, A.; Hils, C.; Hochrein, S.; Hoetzsch, L.; Hoferichter, M.; Hood, N.; Hooper, D.; Horn, M.; Howlett, J.; Huang, D. Q.; Huang, Y.; Hunt, D.; Iacovacci, M.; Iaquaniello, G.; Ide, R.; Ignarra, C. M.; Iloglu, G.; Itow, Y.; Jacquet, E.; Jahangir, O.; Jakob, J.; James, R. S.; Jansen, A.; Ji, W.; Ji, X.; Joerg, F.; Johnson, J.; Joy, A.; Kaboth, A. C.; Kamaha, A. C.; Kanezaki, K.; Kar, K.; Kara, M.; Kato, N.; Kavrigin, P.; Kazama, S.; Keaveney, A. W.; Kellerer, J.; Khaitan, D.; Khazov, A.; Khundzakishvili, G.; Khurana, I.; Kilminster, B.; Kleifges, M.; Ko, P.; Kobayashi, M.; Kobayashi, M.; Kodroff, D.; Koltmann, G.; Kopec, A.; Kopmann, A.; Kopp, J.; Korley, L.; Kornoukhov, V. N.; Korolkova, E. V.; Kraus, H.; Krauss, L. M.; Kravitz, S.; Kreczko, L.; Kudryavtsev, V. A.; Kuger, F.; Kumar, J.; López Paredes, B.; LaCascio, L.; Laine, Q.; Landsman, H.; Lang, R. F.; Leason, E. A.; Lee, J.; Leonard, D. S.; Lesko, K. T.; Levinson, L.; Levy, C.; Li, I.; Li, S. C.; Li, T.; Liang, S.; Liebenthal, C. S.; Lin, J.; Lin, Q.; Lindemann, S.; Lindner, M.; Lindote, A.; Linehan, R.; Lippincott, W. H.; Liu, X.; Liu, K.; Liu, J.; Loizeau, J.; Lombardi, F.; Long, J.; Lopes, M. I.; Lopez Asamar, E.; Lorenzon, W.; Lu, C.; Luitz, S.; Ma, Y.; Machado, P. A. N.; Macolino, C.; Maeda, T.; Mahlstedt, J.; Majewski, P. A.; Manalaysay, A.; Mancuso, A.; Manenti, L.; Manfredini, A.; Mannino, R. L.; Marangou, N.; March-Russell, J.; Marignetti, F.; Marrodán Undagoitia, T.; Martens, K.; Martin, R.; Martinez-Soler, I.; Masbou, J.; Masson, D.; Masson, E.; Mastroianni, S.; Mastronardi, M.; Matias-Lopes, J. A.; McCarthy, M. E.; McFadden, N.; McGinness, E.; McKinsey, D. N.; McLaughlin, J.; McMichael, K.; Meinhardt, P.; Menéndez, J.; Meng, Y.; Messina, M.; Midha, R.; Milisavljevic, D.; Miller, E. H.; Milosevic, B.; Milutinovic, S.; Mitra, S. A.; Miuchi, K.; Mizrachi, E.; Mizukoshi, K.; Molinario, A.; Monte, A.; Monteiro, C. M. B.; Monzani, M. E.; Moore, J. S.; Morå, K.; Morad, J. A.; Morales Mendoza, J. D.; Moriyama, S.; Morrison, E.; Morteau, E.; Mosbacher, Y.; Mount, B. J.; Mueller, J.; Murphy, A. St. J.; Murra, M.; Naim, D.; Nakamura, S.; Nash, E.; Navaieelavasani, N.; Naylor, A.; Nedlik, C.; Nelson, H. N.; Neves, F.; Newstead, J. L.; Ni, K.; Nikoleyczik, J. A.; Niro, V.; Oberlack, U. G.; Obradovic, M.; Odgers, K.; O'Hare, C. A. J.; Oikonomou, P.; Olcina, I.; Oliver-Mallory, K.; Oranday, A.; Orpwood, J.; Ostrovskiy, I.; Ozaki, K.; Paetsch, B.; Pal, S.; Palacio, J.; Palladino, K. J.; Palmer, J.; Panci, P.; Pandurovic, M.; Parlati, A.; Parveen, N.; Patton, S. J.; Pěč, V.; Pellegrini, Q.; Penning, B.; Pereira, G.; Peres, R.; Perez-Gonzalez, Y.; Perry, E.; Pershing, T.; Petrossian-Byrne, R.; Pienaar, J.; Piepke, A.; Pieramico, G.; Pierre, M.; Piotter, M.; Pizella, V.; Plante, G.; Pollmann, T.; Porzio, D.; Qi, J.; Qie, Y.; Qin, J.; Raj, N.; Rajado Silva, M.; Ramanathan, K.; Ramírez García, D.; Ravanis, J.; Redard-Jacot, L.; Redigolo, D.; Reichard, S.; Reichenbacher, J.; Rhyne, C. A.; Richards, A.; Riffard, Q.; Rischbieter, G. R. C.; Rocchetti, A.; Rosenfeld, S. L.; Rosero, R.; Rupp, N.; Rushton, T.; Saha, S.; Sanchez, L.; Sanchez-Lucas, P.; Santone, D.; dos Santos, J. M. F.; Sarnoff, I.; Sartorelli, G.; Sazzad, A. B. M. R.; Scheibelhut, M.; Schnee, R. W.; Schrank, M.; Schreiner, J.; Schulte, P.; Schulte, D.; Schulze Eissing, H.; Schumann, M.; Schwemberger, T.; Schwenk, A.; Schwetz, T.; Scotto Lavina, L.; Scovell, P. R.; Sekiya, H.; Selvi, M.; Semenov, E.; Semeria, F.; Shagin, P.; Shaw, S.; Shi, S.; Shockley, E.; Shutt, T. A.; Si-Ahmed, R.; Silk, J. J.; Silva, C.; Silva, M. C.; Simgen, H.; Šimkovic, F.; Sinev, G.; Singh, R.; Skulski, W.; Smirnov, J.; Smith, R.; Solmaz, M.; Solovov, V. N.; Sorensen, P.; Soria, J.; Sparmann, T. J.; Stancu, I.; Steidl, M.; Stevens, A.; Stifter, K.; Strigari, L. E.; Subotic, D.; Suerfu, B.; Suliga, A. M.; Sumner, T. J.; Szabo, P.; Szydagis, M.; Takeda, A.; Takeuchi, Y.; Tan, P. -L.; Taricco, C.; Taylor, W. C.; Temples, D. J.; Terliuk, A.; Terman, P. A.; Thers, D.; Thieme, K.; Thümmler, Th.; Tiedt, D. R.; Timalsina, M.; To, W. H.; Toennies, F.; Tong, Z.; Toschi, F.; Tovey, D. R.; Tranter, J.; Trask, M.; Trinchero, G. C.; Tripathi, M.; Tronstad, D. R.; Trotta, R.; Tsai, Y. D.; Tunnell, C. D.; Turner, W. G.; Ueno, R.; Urquijo, P.; Utku, U.; Vaitkus, A.; Valerius, K.; Vassilev, E.; Vecchi, S.; Velan, V.; Vetter, S.; Vincent, A. C.; Vittorio, L.; Volta, G.; von Krosigk, B.; von Piechowski, M.; Vorkapic, D.; Wagner, C. E. M.; Wang, A. M.; Wang, B.; Wang, Y.; Wang, W.; Wang, J. J.; Wang, L. -T.; Wang, M.; Wang, Y.; Watson, J. R.; Wei, Y.; Weinheimer, C.; Weisman, E.; Weiss, M.; Wenz, D.; West, S. M.; Whitis, T. J.; Williams, M.; Wilson, M. J.; Winkler, D.; Wittweg, C.; Wolf, J.; Wolf, T.; Wolfs, F. L. H.; Woodford, S.; Woodward, D.; Wright, C. J.; Wu, V. H. S.; Wu, P.; Wüstling, S.; Wurm, M.; Xia, Q.; Xiang, X.; Xing, Y.; Xu, J.; Xu, Z.; Xu, D.; Yamashita, M.; Yamazaki, R.; Yan, H.; Yang, L.; Yang, Y.; Ye, J.; Yeh, M.; Young, I.; Yu, H. B.; Yu, T. T.; Yuan, L.; Zavattini, G.; Zerbo, S.; Zhang, Y.; Zhong, M.; Zhou, N.; Zhou, X.; Zhu, T.; Zhu, Y.; Zhuang, Y.; Zopounidis, J. P.; Zuber, K.; Zupan, J. Bibcode: 2022arXiv220302309A Altcode: The nature of dark matter and properties of neutrinos are among the most pressing issues in contemporary particle physics. The dual-phase xenon time-projection chamber is the leading technology to cover the available parameter space for Weakly Interacting Massive Particles (WIMPs), while featuring extensive sensitivity to many alternative dark matter candidates. These detectors can also study neutrinos through neutrinoless double-beta decay and through a variety of astrophysical sources. A next-generation xenon-based detector will therefore be a true multi-purpose observatory to significantly advance particle physics, nuclear physics, astrophysics, solar physics, and cosmology. This review article presents the science cases for such a detector. Title: Oscillatory Reconnection of a 2D X-point in a Hot Coronal Plasma Authors: Karampelas, Konstantinos; McLaughlin, James A.; Botha, Gert J. J.; Régnier, Stéphane Bibcode: 2022ApJ...925..195K Altcode: 2021arXiv211205712K Oscillatory reconnection (a relaxation mechanism with periodic changes in connectivity) has been proposed as a potential physical mechanism underpinning several periodic phenomena in the solar atmosphere, including, but not limited to, quasi-periodic pulsations (QPPs). Despite its importance, however, the mechanism has never been studied within a hot, coronal plasma. We investigate oscillatory reconnection in a one million Kelvin plasma by solving the fully-compressive, resistive MHD equations for a 2D magnetic X-point under coronal conditions using the PLUTO code. We report on the resulting oscillatory reconnection including its periodicity and decay rate. We observe a more complicated oscillating profile for the current density compared to that found for a cold plasma, due to mode-conversion at the equipartition layer. We also consider, for the first time, the effect of adding anisotropic thermal conduction to the oscillatory reconnection mechanism, and we find this simplifies the spectrum of the oscillation profile and increases the decay rate. Crucially, the addition of thermal conduction does not prevent the oscillatory reconnection mechanism from manifesting. Finally, we reveal a relationship between the equilibrium magnetic field strength, decay rate, and period of oscillatory reconnection, which opens the tantalising possibility of utilizing oscillatory reconnection as a seismological tool. Title: Is phase mixing important in the quiet Sun? Authors: Morton, Richard; McLaughlin, James; Tiwari, Ajay; Van Doorsselaere, Tom Bibcode: 2021AGUFMSH12B..09M Altcode: The focus of many investigations on coronal wave heating has been to scrutinise the role of transverse (i.e. kink) modes; examining their damping by resonant absorption and the transfer of energy to Alfvén modes. Subsequently, the Alfvén modes are then subject to phase mixing and this leads to plasma heating. More recently, a non-linear mechanism for energy transfer has also been proposed, the so called uni-turbulence. Due to the ease with which they have been observed, the rapidly damped standing kink modes in active regions have spawned numerous studies investigating the role of resonant absorption in the observed damping. However, their counterparts in the quiet Sun, the propagating kink waves, have received little attention. Here I will discuss the results from a large-scale study of kink wave damping in the quiet Sun. We find convincing evidence that the damping of the kink waves is significantly weaker than in active regions and suggests that resonant absorption/phase mixing/uni-turbulence are not important mechanisms for wave-based heating of the quiescent Sun. I will also discuss the physical reason we suspect is behind this result and what it tells us about the fine-scale structure of the quiescent corona. Title: Weak Damping of Propagating MHD Kink Waves in the Quiescent Corona Authors: Morton, Richard J.; Tiwari, Ajay K.; Van Doorsselaere, Tom; McLaughlin, James A. Bibcode: 2021ApJ...923..225M Altcode: 2021arXiv210511924M Propagating transverse waves are thought to be a key transporter of Poynting flux throughout the Sun's atmosphere. Recent studies have shown that these transverse motions, interpreted as the magnetohydrodynamic kink mode, are prevalent throughout the corona. The associated energy estimates suggest the waves carry enough energy to meet the demands of coronal radiative losses in the quiescent Sun. However, it is still unclear how the waves deposit their energy into the coronal plasma. We present the results from a large-scale study of propagating kink waves in the quiescent corona using data from the Coronal Multi-channel Polarimeter (CoMP). The analysis reveals that the kink waves appear to be weakly damped, which would imply low rates of energy transfer from the large-scale transverse motions to smaller scales via either uniturbulence or resonant absorption. This raises questions about how the observed kink modes would deposit their energy into the coronal plasma. Moreover, these observations, combined with the results of Monte Carlo simulations, lead us to infer that the solar corona displays a spectrum of density ratios, with a smaller density ratio (relative to the ambient corona) in quiescent coronal loops and a higher density ratio in active-region coronal loops. Title: Projected sensitivities of the LUX-ZEPLIN experiment to new physics via low-energy electron recoils Authors: Akerib, D. S.; Al Musalhi, A. K.; Alsum, S. K.; Amarasinghe, C. S.; Ames, A.; Anderson, T. J.; Angelides, N.; Araújo, H. M.; Armstrong, J. E.; Arthurs, M.; Bai, X.; Balajthy, J.; Balashov, S.; Bang, J.; Bargemann, J. W.; Bauer, D.; Baxter, A.; Beltrame, P.; Bernard, E. P.; Bernstein, A.; Bhatti, A.; Biekert, A.; Biesiadzinski, T. P.; Birch, H. J.; Blockinger, G. M.; Bodnia, E.; Boxer, B.; Brew, C. A. J.; Brás, P.; Burdin, S.; Busenitz, J. K.; Buuck, M.; Cabrita, R.; Carmona-Benitez, M. C.; Cascella, M.; Chan, C.; Chott, N. I.; Cole, A.; Converse, M. V.; Cottle, A.; Cox, G.; Creaner, O.; Cutter, J. E.; Dahl, C. E.; de Viveiros, L.; Dobson, J. E. Y.; Druszkiewicz, E.; Eriksen, S. R.; Fan, A.; Fayer, S.; Fearon, N. M.; Fiorucci, S.; Flaecher, H.; Fraser, E. D.; Fruth, T.; Gaitskell, R. J.; Genovesi, J.; Ghag, C.; Gibson, E.; Gokhale, S.; van der Grinten, M. G. D.; Gwilliam, C. B.; Hall, C. R.; Hardy, C. A.; Haselschwardt, S. J.; Hertel, S. A.; Horn, M.; Huang, D. Q.; Ignarra, C. M.; Jahangir, O.; James, R. S.; Ji, W.; Johnson, J.; Kaboth, A. C.; Kamaha, A. C.; Kamdin, K.; Kazkaz, K.; Khaitan, D.; Khazov, A.; Khurana, I.; Kodroff, D.; Korley, L.; Korolkova, E. V.; Kraus, H.; Kravitz, S.; Kreczko, L.; Krikler, B.; Kudryavtsev, V. A.; Leason, E. A.; Lee, J.; Leonard, D. S.; Lesko, K. T.; Levy, C.; Li, J.; Liao, J.; Lindote, A.; Linehan, R.; Lippincott, W. H.; Liu, X.; Lopes, M. I.; Lopez Asamar, E.; López Paredes, B.; Lorenzon, W.; Luitz, S.; Majewski, P. A.; Manalaysay, A.; Manenti, L.; Mannino, R. L.; Marangou, N.; McCarthy, M. E.; McKinsey, D. N.; McLaughlin, J.; Miller, E. H.; Mizrachi, E.; Monte, A.; Monzani, M. E.; Morad, J. A.; Morales Mendoza, J. D.; Morrison, E.; Mount, B. J.; Murphy, A. St. J.; Naim, D.; Naylor, A.; Nedlik, C.; Nelson, H. N.; Neves, F.; Nikoleyczik, J. A.; Nilima, A.; Nguyen, A.; Olcina, I.; Oliver-Mallory, K. C.; Pal, S.; Palladino, K. J.; Palmer, J.; Patton, S.; Parveen, N.; Pease, E. K.; Penning, B.; Pereira, G.; Piepke, A.; Qie, Y.; Reichenbacher, J.; Rhyne, C. A.; Richards, A.; Riffard, Q.; Rischbieter, G. R. C.; Rosero, R.; Rossiter, P.; Santone, D.; Sazzad, A. B. M. R.; Schnee, R. W.; Scovell, P. R.; Shaw, S.; Shutt, T. A.; Silk, J. J.; Silva, C.; Smith, R.; Solmaz, M.; Solovov, V. N.; Sorensen, P.; Soria, J.; Stancu, I.; Stevens, A.; Stifter, K.; Suerfu, B.; Sumner, T. J.; Swanson, N.; Szydagis, M.; Taylor, W. C.; Taylor, R.; Temples, D. J.; Terman, P. A.; Tiedt, D. R.; Timalsina, M.; To, W. H.; Tovey, D. R.; Tripathi, M.; Tronstad, D. R.; Turner, W.; Utku, U.; Vaitkus, A.; Wang, B.; Wang, J. J.; Wang, W.; Watson, J. R.; Webb, R. C.; White, R. G.; Whitis, T. J.; Williams, M.; Wolfs, F. L. H.; Woodward, D.; Wright, C. J.; Xiang, X.; Xu, J.; Yeh, M.; Zarzhitsky, P. Bibcode: 2021PhRvD.104i2009A Altcode: 2021arXiv210211740T LUX-ZEPLIN is a dark matter detector expected to obtain world-leading sensitivity to weakly-interacting massive particles interacting via nuclear recoils with a ∼7 -tonne xenon target mass. This paper presents sensitivity projections to several low-energy signals of the complementary electron recoil signal type: 1) an effective neutrino magnetic moment, and 2) an effective neutrino millicharge, both for p p -chain solar neutrinos, 3) an axion flux generated by the Sun, 4) axionlike particles forming the Galactic dark matter, 5) hidden photons, 6) mirror dark matter, and 7) leptophilic dark matter. World-leading sensitivities are expected in each case, a result of the large 5.6 t 1000 d exposure and low expected rate of electron-recoil backgrounds in the <100 keV energy regime. A consistent signal generation, background model and profile-likelihood analysis framework is used throughout. Title: A Statistical Study of Propagating MHD Kink Waves in the Quiescent Corona Authors: Tiwari, Ajay K.; Morton, Richard J.; McLaughlin, James A. Bibcode: 2021ApJ...919...74T Altcode: 2021arXiv210512451T The Coronal Multi-channel Polarimeter (CoMP) has opened up exciting opportunities to probe transverse MHD waves in the Sun's corona. The archive of CoMP data is utilized to generate a catalog of quiescent coronal loops that can be used for studying propagating kink waves. The catalog contains 120 loops observed between 2012 and 2014. This catalog is further used to undertake a statistical study of propagating kink waves in the quiet regions of the solar corona, investigating phase speeds, loop lengths, footpoint power ratio (a measure of wave power entering the corona through each footpoint of a loop) and equilibrium parameter (which provides a measure of the change in wave amplitude) values. The statistical study enables us to establish the presence of a relationship between the rate of damping and the length of the coronal loop, with longer coronal loops displaying weaker wave damping. We suggest the reason for this behavior is related to a decreasing average density contrast between the loop and ambient plasma as loop length increases. The catalog presented here will provide the community with the foundation for the further study of propagating kink waves in the quiet solar corona. Title: Magnetohydrodynamic Waves in Open Coronal Structures Authors: Banerjee, D.; Krishna Prasad, S.; Pant, V.; McLaughlin, J. A.; Antolin, P.; Magyar, N.; Ofman, L.; Tian, H.; Van Doorsselaere, T.; De Moortel, I.; Wang, T. J. Bibcode: 2021SSRv..217...76B Altcode: 2020arXiv201208802B Modern observatories have revealed the ubiquitous presence of magnetohydrodynamic waves in the solar corona. The propagating waves (in contrast to the standing waves) are usually originated in the lower solar atmosphere which makes them particularly relevant to coronal heating. Furthermore, open coronal structures are believed to be the source regions of solar wind, therefore, the detection of MHD waves in these structures is also pertinent to the acceleration of solar wind. Besides, the advanced capabilities of the current generation telescopes have allowed us to extract important coronal properties through MHD seismology. The recent progress made in the detection, origin, and damping of both propagating slow magnetoacoustic waves and kink (Alfvénic) waves is presented in this review article especially in the context of open coronal structures. Where appropriate, we give an overview on associated theoretical modelling studies. A few of the important seismological applications of these waves are discussed. The possible role of Alfvénic waves in the acceleration of solar wind is also touched upon. Title: Quasi-Periodic Pulsations in Solar and Stellar Flares: A Review of Underpinning Physical Mechanisms and Their Predicted Observational Signatures Authors: Zimovets, I. V.; McLaughlin, J. A.; Srivastava, A. K.; Kolotkov, D. Y.; Kuznetsov, A. A.; Kupriyanova, E. G.; Cho, I. -H.; Inglis, A. R.; Reale, F.; Pascoe, D. J.; Tian, H.; Yuan, D.; Li, D.; Zhang, Q. M. Bibcode: 2021SSRv..217...66Z Altcode: The phenomenon of quasi-periodic pulsations (QPPs) in solar and stellar flares has been known for over 50 years and significant progress has been made in this research area. It has become clear that QPPs are not rare—they are found in many flares and, therefore, robust flare models should reproduce their properties in a natural way. At least fifteen mechanisms/models have been developed to explain QPPs in solar flares, which mainly assume the presence of magnetohydrodynamic (MHD) oscillations in coronal structures (magnetic loops and current sheets) or quasi-periodic regimes of magnetic reconnection. We review the most important and interesting results on flare QPPs, with an emphasis on the results of recent years, and we present the predicted and prominent observational signatures of each of the fifteen mechanisms. However, it is not yet possible to draw an unambiguous conclusion as to the correct underlying QPP mechanism because of the qualitative, rather than quantitative, nature of most of the models and also due to insufficient observational information on the physical properties of the flare region, in particular the spatial structure of the QPP source. We also review QPPs in stellar flares, where progress is largely based on solar-stellar analogies, suggesting similarities in the physical processes in flare regions on the Sun and magnetoactive stars. The presence of QPPs with similar properties in solar and stellar flares is, in itself, a strong additional argument in favor of the likelihood of solar-stellar analogies. Hence, advancing our understanding of QPPs in solar flares provides an important additional channel of information about stellar flares. However, further work in both theory/simulations and in observations is needed. Title: Separating 39Ar from 40Ar by cryogenic distillation with Aria for dark-matter searches Authors: Agnes, P.; Albergo, S.; Albuquerque, I. F. M.; Alexander, T.; Alici, A.; Alton, A. K.; Amaudruz, P.; Arba, M.; Arpaia, P.; Arcelli, S.; Ave, M.; Avetissov, I. Ch.; Avetisov, R. I.; Azzolini, O.; Back, H. O.; Balmforth, Z.; Barbarian, V.; Barrado Olmedo, A.; Barrillon, P.; Basco, A.; Batignani, G.; Bondar, A.; Bonivento, W. M.; Borisova, E.; Bottino, B.; Boulay, M. G.; Buccino, G.; Bussino, S.; Busto, J.; Buzulutskov, A.; Cadeddu, M.; Cadoni, M.; Caminata, A.; Canesi, E. V.; Canci, N.; Cappello, G.; Caravati, M.; Cárdenas-Montes, M.; Cargioli, N.; Carlini, M.; Carnesecchi, F.; Castello, P.; Castellani, A.; Catalanotti, S.; Cataudella, V.; Cavalcante, P.; Cavuoti, S.; Cebrian, S.; Cela Ruiz, J. M.; Celano, B.; Chashin, S.; Chepurnov, A.; Cicalò, C.; Cifarelli, L.; Cintas, D.; Coccetti, F.; Cocco, V.; Colocci, M.; Conde Vilda, E.; Consiglio, L.; Copello, S.; Corning, J.; Covone, G.; Czudak, P.; D'Aniello, M.; D'Auria, S.; Da Rocha Rolo, M. D.; Dadoun, O.; Daniel, M.; Davini, S.; De Candia, A.; De Cecco, S.; De Falco, A.; De Filippis, G.; De Gruttola, D.; De Guido, G.; De Rosa, G.; Della Valle, M.; Dellacasa, G.; De Pasquale, S.; Derbin, A. V.; Devoto, A.; Di Noto, L.; Di Eusanio, F.; Dionisi, C.; Di Stefano, P.; Dolganov, G.; Dongiovanni, D.; Dordei, F.; Downing, M.; Erjavec, T.; Falciano, S.; Farenzena, S.; Fernandez Diaz, M.; Filip, C.; Fiorillo, G.; Franceschi, A.; Franco, D.; Frolov, E.; Funicello, N.; Gabriele, F.; Galbiati, C.; Garbini, M.; Garcia Abia, P.; Gendotti, A.; Ghiano, C.; Giampaolo, R. A.; Giganti, C.; Giorgi, M. A.; Giovanetti, G. K.; Gligan, M. L.; Goicoechea Casanueva, V.; Gola, A.; Goretti, A. M.; Graciani Diaz, R.; Grigoriev, G. Y.; Grobov, A.; Gromov, M.; Guan, M.; Guerzoni, M.; Guetti, M.; Gulino, M.; Guo, C.; Hackett, B. R.; Hallin, A.; Haranczyk, M.; Hill, S.; Horikawa, S.; Hubaut, F.; Hugues, T.; Hungerford, E. V.; Ianni, An.; Ippolito, V.; James, C. C.; Jillings, C.; Kachru, P.; Kemp, A. A.; Kendziora, C. L.; Keppel, G.; Khomyakov, A. V.; Kish, A.; Kochanek, I.; Kondo, K.; Korga, G.; Kubankin, A.; Kugathasan, R.; Kuss, M.; Kuźniak, M.; La Commara, M.; La Delfa, L.; La Grasta, D.; Lai, M.; Lami, N.; Langrock, S.; Leyton, M.; Li, X.; Lidey, L.; Lippi, F.; Lissia, M.; Longo, G.; Maccioni, N.; Machulin, I. N.; Mapelli, L.; Marasciulli, A.; Margotti, A.; Mari, S. M.; Maricic, J.; Marinelli, M.; Martínez, M.; Martinez Rojas, A. D.; Martini, A.; Mascia, M.; Masetto, M.; Masoni, A.; Mazzi, A.; McDonald, A. B.; Mclaughlin, J.; Messina, A.; Meyers, P. D.; Miletic, T.; Milincic, R.; Miola, R.; Moggi, A.; Moharana, A.; Moioli, S.; Monroe, J.; Morisi, S.; Morrocchi, M.; Mozhevitina, E. N.; Mróz, T.; Muratova, V. N.; Murenu, A.; Muscas, C.; Musenich, L.; Musico, P.; Nania, R.; Napolitano, T.; Navrer Agasson, A.; Nessi, M.; Nikulin, I.; Nowak, J.; Oleinik, A.; Oleynikov, V.; Pagani, L.; Pallavicini, M.; Palmas, S.; Pandola, L.; Pantic, E.; Paoloni, E.; Paternoster, G.; Pegoraro, P. A.; Pellegrini, L. A.; Pellegrino, C.; Pelczar, K.; Perotti, F.; Pesudo, V.; Picciau, E.; Pietropaolo, F.; Pinna, T.; Pocar, A.; Podda, P.; Poehlmann, D. M.; Pordes, S.; Poudel, S. S.; Pralavorio, P.; Price, D.; Raffaelli, F.; Ragusa, F.; Ramirez, A.; Razeti, M.; Razeto, A.; Renshaw, A. L.; Rescia, S.; Rescigno, M.; Resnati, F.; Retiere, F.; Rignanese, L. P.; Ripoli, C.; Rivetti, A.; Rode, J.; Romero, L.; Rossi, M.; Rubbia, A.; Rucaj, M.; Sabiu, G. M.; Salatino, P.; Samoylov, O.; Sánchez García, E.; Sandford, E.; Sanfilippo, S.; Sangiorgio, V. A.; Santacroce, V.; Santone, D.; Santorelli, R.; Santucci, A.; Savarese, C.; Scapparone, E.; Schlitzer, B.; Scioli, G.; Semenov, D. A.; Shaw, B.; Shchagin, A.; Sheshukov, A.; Simeone, M.; Skensved, P.; Skorokhvatov, M. D.; Smirnov, O.; Smith, B.; Sokolov, A.; Stefanizzi, R.; Steri, A.; Stracka, S.; Strickland, V.; Stringer, M.; Sulis, S.; Suvorov, Y.; Szelc, A. M.; Szucs-Balazs, J. Z.; Tartaglia, R.; Testera, G.; Thorpe, T. N.; Tonazzo, A.; Torres-Lara, S.; Tosti, S.; Tricomi, A.; Tuveri, M.; Unzhakov, E. V.; Usai, G.; Vallivilayil John, T.; Vescovi, S.; Viant, T.; Viel, S.; Vishneva, A.; Vogelaar, R. B.; Wada, M.; Wang, H.; Wang, Y.; Westerdale, S.; Wheadon, R. J.; Williams, L.; M. Wojcik, Ma.; Wojcik, Ma.; Xiao, X.; Yang, C.; Zani, A.; Zenobio, F.; Zichichi, A.; Zuzel, G.; Zykova, M. P.; DarkSide-20k Collaboration Bibcode: 2021EPJC...81..359A Altcode: 2021arXiv210108686D Aria is a plant hosting a 350 m cryogenic isotopic distillation column, the tallest ever built, which is being installed in a mine shaft at Carbosulcis S.p.A., Nuraxi-Figus (SU), Italy. Aria is one of the pillars of the argon dark-matter search experimental program, lead by the Global Argon Dark Matter Collaboration. It was designed to reduce the isotopic abundance of 39Ar in argon extracted from underground sources, called Underground Argon (UAr), which is used for dark-matter searches. Indeed, 39Ar is a β -emitter of cosmogenic origin, whose activity poses background and pile-up concerns in the detectors. In this paper, we discuss the requirements, design, construction, tests, and projected performance of the plant for the isotopic cryogenic distillation of argon. We also present the successful results of the isotopic cryogenic distillation of nitrogen with a prototype plant. Title: Sensitivity of future liquid argon dark matter search experiments to core-collapse supernova neutrinos Authors: DarkSide-20k Collaboration; Agnes, P.; Albergo, S.; Albuquerque, I. F. M.; Alexander, T.; Alici, A.; Alton, A. K.; Amaudruz, P.; Arcelli, S.; Ave, M.; Avetissov, I. Ch.; Avetisov, R. I.; Azzolini, O.; Back, H. O.; Balmforth, Z.; Barbarian, V.; Barrado Olmedo, A.; Barrillon, P.; Basco, A.; Batignani, G.; Bondar, A.; Bonivento, W. M.; Borisova, E.; Bottino, B.; Boulay, M. G.; Buccino, G.; Bussino, S.; Busto, J.; Buzulutskov, A.; Cadeddu, M.; Cadoni, M.; Caminata, A.; Canci, N.; Cappello, G.; Caravati, M.; Cárdenas-Montes, M.; Carlini, M.; Carnesecchi, F.; Castello, P.; Catalanotti, S.; Cataudella, V.; Cavalcante, P.; Cavuoti, S.; Cebrian, S.; Cela Ruiz, J. M.; Celano, B.; Chashin, S.; Chepurnov, A.; Chyhyrynets, E.; Cicalò, C.; Cifarelli, L.; Cintas, D.; Coccetti, F.; Cocco, V.; Colocci, M.; Conde Vilda, E.; Consiglio, L.; Copello, S.; Corning, J.; Covone, G.; Czudak, P.; D'Auria, S.; Da Rocha Rolo, M. D.; Dadoun, O.; Daniel, M.; Davini, S.; De Candia, A.; De Cecco, S.; De Falco, A.; De Filippis, G.; De Gruttola, D.; De Guido, G.; De Rosa, G.; Della Valle, M.; Dellacasa, G.; De Pasquale, S.; Derbin, A. V.; Devoto, A.; Di Noto, L.; Dionisi, C.; Di Stefano, P.; Dolganov, G.; Dordei, F.; Doria, L.; Downing, M.; Erjavec, T.; Fernandez Diaz, M.; Fiorillo, G.; Franceschi, A.; Franco, D.; Frolov, E.; Funicello, N.; Gabriele, F.; Galbiati, C.; Garbini, M.; Garcia Abia, P.; Gendotti, A.; Ghiano, C.; Giampaolo, R. A.; Giganti, C.; Giorgi, M. A.; Giovanetti, G. K.; Goicoechea Casanueva, V.; Gola, A.; Graciani Diaz, R.; Grigoriev, G. Y.; Grobov, A.; Gromov, M.; Guan, M.; Guerzoni, M.; Gulino, M.; Guo, C.; Hackett, B. R.; Hallin, A.; Haranczyk, M.; Hill, S.; Horikawa, S.; Hubaut, F.; Hugues, T.; Hungerford, E. V.; Ianni, An.; Ippolito, V.; James, C. C.; Jillings, C.; Kachru, P.; Kemp, A. A.; Kendziora, C. L.; Keppel, G.; Khomyakov, A. V.; Kim, S.; Kish, A.; Kochanek, I.; Kondo, K.; Korga, G.; Kubankin, A.; Kugathasan, R.; Kuss, M.; Kuźniak, M.; La Commara, M.; Lai, M.; Langrock, S.; Leyton, M.; Li, X.; Lidey, L.; Lissia, M.; Longo, G.; Machulin, I. N.; Mapelli, L.; Marasciulli, A.; Margotti, A.; Mari, S. M.; Maricic, J.; Martínez, M.; Martinez Rojas, A. D.; Martoff, C. J.; Masoni, A.; Mazzi, A.; McDonald, A. B.; Mclaughlin, J.; Messina, A.; Meyers, P. D.; Miletic, T.; Milincic, R.; Moggi, A.; Moharana, A.; Moioli, S.; Monroe, J.; Morisi, S.; Morrocchi, M.; Mozhevitina, E. N.; Mróz, T.; Muratova, V. N.; Muscas, C.; Musenich, L.; Musico, P.; Nania, R.; Napolitano, T.; Navrer Agasson, A.; Nessi, M.; Nikulin, I.; Nowak, J.; Oleinik, A.; Oleynikov, V.; Pagani, L.; Pallavicini, M.; Pandola, L.; Pantic, E.; Paoloni, E.; Paternoster, G.; Pegoraro, P. A.; Pelczar, K.; Pellegrini, L. A.; Pellegrino, C.; Perotti, F.; Pesudo, V.; Picciau, E.; Pietropaolo, F.; Pira, C.; Pocar, A.; Poehlmann, D. M.; Pordes, S.; Poudel, S. S.; Pralavorio, P.; Price, D.; Raffaelli, F.; Ragusa, F.; Ramirez, A.; Razeti, M.; Razeto, A.; Renshaw, A. L.; Rescia, S.; Rescigno, M.; Resnati, F.; Retiere, F.; Rignanese, L. P.; Ripoli, C.; Rivetti, A.; Rode, J.; Romero, L.; Rossi, M.; Rubbia, A.; Salatino, P.; Samoylov, O.; Sánchez García, E.; Sandford, E.; Sanfilippo, S.; Santone, D.; Santorelli, R.; Savarese, C.; Scapparone, E.; Schlitzer, B.; Scioli, G.; Semenov, D. A.; Shaw, B.; Shchagin, A.; Sheshukov, A.; Simeone, M.; Skensved, P.; Skorokhvatov, M. D.; Smirnov, O.; Smith, B.; Sokolov, A.; Steri, A.; Stracka, S.; Strickland, V.; Stringer, M.; Sulis, S.; Suvorov, Y.; Szelc, A. M.; Tartaglia, R.; Testera, G.; Thorpe, T. N.; Tonazzo, A.; Torres-Lara, S.; Tricomi, A.; Unzhakov, E. V.; Usai, G.; Vallivilayil John, T.; Viant, T.; Viel, S.; Vishneva, A.; Vogelaar, R. B.; Wada, M.; Wang, H.; Wang, Y.; Westerdale, S.; Wheadon, R. J.; Williams, L.; Wojcik, Ma. M.; Wojcik, Ma.; Xiao, X.; Yang, C.; Ye, Z.; Zani, A.; Zichichi, A.; Zuzel, G.; Zykova, M. P. Bibcode: 2021JCAP...03..043D Altcode: 2021JCAP...03..043T; 2020arXiv201107819A Future liquid-argon DarkSide-20k and Argo detectors, designed for direct dark matter search, will be sensitive also to core-collapse supernova neutrinos, via coherent elastic neutrino-nucleus scattering. This interaction channel is flavor-insensitive with a high-cross section, enabling for a high-statistics neutrino detection with target masses of ∼50 t and ∼360 t for DarkSide-20k and Argo respectively. Thanks to the low-energy threshold of ∼0.5 keVnr achievable by exploiting the ionization channel, DarkSide-20k and Argo have the potential to discover supernova bursts throughout our galaxy and up to the Small Magellanic Cloud, respectively, assuming a 11-M progenitor star. We report also on the sensitivity to the neutronization burst, whose electron neutrino flux is suppressed by oscillations when detected via charged current and elastic scattering. Finally, the accuracies in the reconstruction of the average and total neutrino energy in the different phases of the supernova burst, as well as its time profile, are also discussed, taking into account the expected background and the detector response. Title: Simulations of events for the LUX-ZEPLIN (LZ) dark matter experiment Authors: Akerib, D. S.; Akerlof, C. W.; Alqahtani, A.; Alsum, S. K.; Anderson, T. J.; Angelides, N.; Araújo, H. M.; Armstrong, J. E.; Arthurs, M.; Bai, X.; Balajthy, J.; Balashov, S.; Bang, J.; Bauer, D.; Baxter, A.; Bensinger, J.; Bernard, E. P.; Bernstein, A.; Bhatti, A.; Biekert, A.; Biesiadzinski, T. P.; Birch, H. J.; Boast, K. E.; Boxer, B.; Brás, P.; Buckley, J. H.; Bugaev, V. V.; Burdin, S.; Busenitz, J. K.; Cabrita, R.; Carels, C.; Carlsmith, D. L.; Carmona-Benitez, M. C.; Cascella, M.; Chan, C.; Chott, N. I.; Cole, A.; Cottle, A.; Cutter, J. E.; Dahl, C. E.; Viveiros, L. de; Dobson, J. E. Y.; Druszkiewicz, E.; Edberg, T. K.; Eriksen, S. R.; Fan, A.; Fayer, S.; Fiorucci, S.; Flaecher, H.; Fraser, E. D.; Fruth, T.; Gaitskell, R. J.; Genovesi, J.; Ghag, C.; Gibson, E.; Gilchriese, M. G. D.; Gokhale, S.; van der Grinten, M. G. D.; Hall, C. R.; Harrison, A.; Haselschwardt, S. J.; Hertel, S. A.; Hor, J. Y. -K.; Horn, M.; Huang, D. Q.; Ignarra, C. M.; Jahangir, O.; Ji, W.; Johnson, J.; Kaboth, A. C.; Kamaha, A. C.; Kamdin, K.; Kazkaz, K.; Khaitan, D.; Khazov, A.; Khurana, I.; Kocher, C. D.; Korley, L.; Korolkova, E. V.; Kras, J.; Kraus, H.; Kravitz, S.; Kreczko, L.; Krikler, B.; Kudryavtsev, V. A.; Leason, E. A.; Lee, J.; Leonard, D. S.; Lesko, K. T.; Levy, C.; Li, J.; Liao, J.; Liao, F. -T.; Lin, J.; Lindote, A.; Linehan, R.; Lippincott, W. H.; Liu, R.; Liu, X.; Loniewski, C.; Lopes, M. I.; López Paredes, B.; Lorenzon, W.; Luitz, S.; Lyle, J. M.; Majewski, P. A.; Manalaysay, A.; Manenti, L.; Mannino, R. L.; Marangou, N.; Marzioni, M. F.; McKinsey, D. N.; McLaughlin, J.; Meng, Y.; Miller, E. H.; Mizrachi, E.; Monte, A.; Monzani, M. E.; Morad, J. A.; Morrison, E.; Mount, B. J.; Murphy, A. St. J.; Naim, D.; Naylor, A.; Nedlik, C.; Nehrkorn, C.; Nelson, H. N.; Neves, F.; Nikoleyczik, J. A.; Nilima, A.; Olcina, I.; Oliver-Mallory, K. C.; Pal, S.; Palladino, K. J.; Palmer, J.; Parveen, N.; Pease, E. K.; Penning, B.; Pereira, G.; Piepke, A.; Pushkin, K.; Reichenbacher, J.; Rhyne, C. A.; Richards, A.; Riffard, Q.; Rischbieter, G. R. C.; Rosero, R.; Rossiter, P.; Rutherford, G.; Santone, D.; Sazzad, A. B. M. R.; Schnee, R. W.; Schubnell, M.; Scovell, P. R.; Seymour, D.; Shaw, S.; Shutt, T. A.; Silk, J. J.; Silva, C.; Smith, R.; Solmaz, M.; Solovov, V. N.; Sorensen, P.; Stancu, I.; Stevens, A.; Stifter, K.; Sumner, T. J.; Swanson, N.; Szydagis, M.; Tan, M.; Taylor, W. C.; Taylor, R.; Temples, D. J.; Terman, P. A.; Tiedt, D. R.; Timalsina, M.; Tomás, A.; Tripathi, M.; Tronstad, D. R.; Turner, W.; Tvrznikova, L.; Utku, U.; Vacheret, A.; Vaitkus, A.; Wang, J. J.; Wang, W.; Watson, J. R.; Webb, R. C.; White, R. G.; Whitis, T. J.; Wolfs, F. L. H.; Woodward, D.; Xiang, X.; Xu, J.; Yeh, M.; Zarzhitsky, P. Bibcode: 2021APh...12502480A Altcode: The LUX-ZEPLIN dark matter search aims to achieve a sensitivity to the WIMP-nucleon spin-independent cross-section down to (1-2) ×10-12 pb at a WIMP mass of 40 GeV/c2. This paper describes the simulations framework that, along with radioactivity measurements, was used to support this projection, and also to provide mock data for validating reconstruction and analysis software. Of particular note are the event generators, which allow us to model the background radiation, and the detector response physics used in the production of raw signals, which can be converted into digitized waveforms similar to data from the operational detector. Inclusion of the detector response allows us to process simulated data using the same analysis routines as developed to process the experimental data. Title: Enhancing the sensitivity of the LUX-ZEPLIN (LZ) dark matter experiment to low energy signals Authors: Akerib, D. S.; Al Musalhi, A. K.; Alsum, S. K.; Amarasinghe, C. S.; Ames, A.; Anderson, T. J.; Angelides, N.; Araújo, H. M.; Armstrong, J. E.; Arthurs, M.; Bai, X.; Balajthy, J.; Balashov, S.; Bang, J.; Bargemann, J. W.; Bauer, D.; Baxter, A.; Beltrame, P.; Bernard, E. P.; Bernstein, A.; Bhatti, A.; Biekert, A.; Biesiadzinski, T. P.; Birch, H. J.; Blockinger, G. M.; Boxer, B.; Brew, C. A. J.; Brás, P.; Burdin, S.; Busenitz, J. K.; Buuck, M.; Cabrita, R.; Carmona-Benitez, M. C.; Cascella, M.; Chan, C.; Chott, N. I.; Cole, A.; Converse, M. V.; Cottle, A.; Cox, G.; Cutter, J. E.; Dahl, C. E.; de Viveiros, L.; Dobson, J. E. Y.; Druszkiewicz, E.; Eriksen, S. R.; Fan, A.; Fayer, S.; Fearon, N. M.; Fiorucci, S.; Flaecher, H.; Fraser, E. D.; Fruth, T.; Gaitskell, R. J.; Genovesi, J.; Ghag, C.; Gibson, E.; Gokhale, S.; van der Grinten, M. G. D.; Gwilliam, C. B.; Hall, C. R.; Haselschwardt, S. J.; Hertel, S. A.; Horn, M.; Huang, D. Q.; Ignarra, C. M.; Jahangir, O.; James, R. S.; Ji, W.; Johnson, J.; Kaboth, A. C.; Kamaha, A. C.; Kamdin, K.; Kazkaz, K.; Khaitan, D.; Khazov, A.; Khurana, I.; Kodroff, D.; Korley, L.; Korolkova, E. V.; Kraus, H.; Kravitz, S.; Kreczko, L.; Krikler, B.; Kudryavtsev, V. A.; Leason, E. A.; Lesko, K. T.; Levy, C.; Li, J.; Liao, J.; Lin, J.; Lindote, A.; Linehan, R.; Lippincott, W. H.; Liu, X.; Lopes, M. I.; Lopez Asamar, E.; López Paredes, B.; Lorenzon, W.; Luitz, S.; Majewski, P. A.; Manalaysay, A.; Manenti, L.; Mannino, R. L.; Marangou, N.; McCarthy, M. E.; McKinsey, D. N.; McLaughlin, J.; Miller, E. H.; Mizrachi, E.; Monte, A.; Monzani, M. E.; Morad, J. A.; Morales Mendoza, J. D.; Morrison, E.; Mount, B. J.; Murphy, A. St. J.; Naim, D.; Naylor, A.; Nedlik, C.; Nelson, H. N.; Neves, F.; Nikoleyczik, J. A.; Olcina, I.; Oliver-Mallory, K. C.; Pal, S.; Palladino, K. J.; Palmer, J.; Parveen, N.; Pease, E. K.; Penning, B.; Pereira, G.; Piepke, A.; Qie, Y.; Reichenbacher, J.; Rhyne, C. A.; Richards, A.; Riffard, Q.; Rischbieter, G. R. C.; Rosero, R.; Rossiter, P.; Santone, D.; Sazzad, A. B. M. R.; Schnee, R. W.; Scovell, P. R.; Shaw, S.; Shutt, T. A.; Silk, J. J.; Silva, C.; Smith, R.; Solmaz, M.; Solovov, V. N.; Sorensen, P.; Stancu, I.; Stevens, A.; Stifter, K.; Suerfu, B.; Sumner, T. J.; Swanson, N.; Szydagis, M.; Taylor, W. C.; Taylor, R.; Temples, D. J.; Terman, P. A.; Tiedt, D. R.; Timalsina, M.; To, W. H.; Tripathi, M.; Tronstad, D. R.; Turner, W.; Utku, U.; Vaitkus, A.; Wang, B.; Wang, J. J.; Wang, W.; Watson, J. R.; Webb, R. C.; White, R. G.; Whitis, T. J.; Williams, M.; Wolfs, F. L. H.; Woodward, D.; Wright, C. J.; Xiang, X.; Xu, J.; Yeh, M.; Zarzhitsky, P. Bibcode: 2021arXiv210108753A Altcode: Two-phase xenon detectors, such as that at the core of the forthcoming LZ dark matter experiment, use photomultiplier tubes to sense the primary (S1) and secondary (S2) scintillation signals resulting from particle interactions in their liquid xenon target. This paper describes a simulation study exploring two techniques to lower the energy threshold of LZ to gain sensitivity to low-mass dark matter and astrophysical neutrinos, which will be applicable to other liquid xenon detectors. The energy threshold is determined by the number of detected S1 photons; typically, these must be recorded in three or more photomultiplier channels to avoid dark count coincidences that mimic real signals. To lower this threshold: a) we take advantage of the double photoelectron emission effect, whereby a single vacuum ultraviolet photon has a $\sim20\%$ probability of ejecting two photoelectrons from a photomultiplier tube photocathode; and b) we drop the requirement of an S1 signal altogether, and use only the ionization signal, which can be detected more efficiently. For both techniques we develop signal and background models for the nominal exposure, and explore accompanying systematic effects, including the dependence on the free electron lifetime in the liquid xenon. When incorporating double photoelectron signals, we predict a factor of $\sim 4$ sensitivity improvement to the dark matter-nucleon scattering cross-section at $2.5$ GeV/c$^2$, and a factor of $\sim1.6$ increase in the solar $^8$B neutrino detection rate. Dropping the S1 requirement may allow sensitivity gains of two orders of magnitude in both cases. Finally, we apply these techniques to even lower masses by taking into account the atomic Migdal effect; this could lower the dark matter particle mass threshold to $80$ MeV/c$^2$. Title: Using Transverse Waves to Probe the Plasma Conditions at the Base of the Solar Wind Authors: Weberg, Micah J.; Morton, Richard J.; McLaughlin, James A. Bibcode: 2020ApJ...894...79W Altcode: It has long been suggested that magnetohydrodynamic (MHD) waves may supply a significant proportion of the energy required to heat the corona and accelerate the solar wind. Depending on the properties of the local plasma, MHD wave modes may exhibit themselves as a variety of incompressible, transverse waves. The local magnetic field and particle density influence the properties of these waves (e.g., amplitude), thus direct measurements of transverse waves provide a mechanism to indirectly probe the local plasma conditions. We present the first statistical approach to magnetoseismology of a localized region of the solar corona, analyzing transverse waves above the south polar coronal hole on 2011 May 23. Automated methods are utilized to examine 4 hr of EUV imaging data to study how the waves evolve as a function of height (I.e., altitude) through the low corona. Between heights of 15 and 35 Mm, we find that the measured wave periods are approximately constant, and that observed displacement and velocity amplitudes increase at rates that are consistent with undamped waves. This enables us to derive a relative density profile for the coronal hole environment in question, without the use of spectroscopic data. Furthermore, our results indicate that between 5 and 15 Mm above the limb, the relative density is larger than that expected from 1D hydrostatic models, and signals a more extended transition region with a gradual change in density. This has implications for self-consistent models of wave propagation from the photosphere to the corona and beyond. Title: Measurement of the gamma ray background in the Davis cavern at the Sanford Underground Research Facility Authors: Akerib, D. S.; Akerlof, C. W.; Alsum, S. K.; Angelides, N.; Araújo, H. M.; Armstrong, J. E.; Arthurs, M.; Bai, X.; Balajthy, J.; Balashov, S.; Baxter, A.; Bernard, E. P.; Biekert, A.; Biesiadzinski, T. P.; Boast, K. E.; Boxer, B.; Brás, P.; Buckley, J. H.; Bugaev, V. V.; Burdin, S.; Busenitz, J. K.; Carels, C.; Carlsmith, D. L.; Carmona-Benitez, M. C.; Cascella, M.; Chan, C.; Cole, A.; Cottle, A.; Cutter, J. E.; Dahl, C. E.; de Viveiros, L.; Dobson, J. E. Y.; Druszkiewicz, E.; Edberg, T. K.; Fan, A.; Fiorucci, S.; Flaecher, H.; Fruth, T.; Gaitskell, R. J.; Genovesi, J.; Ghag, C.; Gilchriese, M. G. D.; Gokhale, S.; van der Grinten, M. G. D.; Hall, C. R.; Hans, S.; Harrison, J.; Haselschwardt, S. J.; Hertel, S. A.; Hor, J. Y. -K.; Horn, M.; Huang, D. Q.; Ignarra, C. M.; Jahangir, O.; Ji, W.; Johnson, J.; Kaboth, A. C.; Kamdin, K.; Khaitan, D.; Khazov, A.; Kim, W. T.; Kocher, C. D.; Korley, L.; Korolkova, E. V.; Kras, J.; Kraus, H.; Kravitz, S. W.; Kreczko, L.; Krikler, B.; Kudryavtsev, V. A.; Leason, E. A.; Lee, J.; Leonard, D. S.; Lesko, K. T.; Levy, C.; Li, J.; Liao, J.; Liao, F. -T.; Lin, J.; Lindote, A.; Linehan, R.; Lippincott, W. H.; Liu, R.; Liu, X.; Loniewski, C.; Lopes, M. I.; López Paredes, B.; Lorenzon, W.; Luitz, S.; Lyle, J. M.; Majewski, P. A.; Manalaysay, A.; Manenti, L.; Mannino, R. L.; Marangou, N.; Marzioni, M. F.; McKinsey, D. N.; McLaughlin, J.; Meng, Y.; Miller, E. H.; Monzani, M. E.; Morad, J. A.; Morrison, E.; Mount, B. J.; Murphy, A. St. J.; Naim, D.; Naylor, A.; Nedlik, C.; Nehrkorn, C.; Nelson, H. N.; Neves, F.; Nikoleyczik, J.; Nilima, A.; Olcina, I.; Oliver-Mallory, K. C.; Pal, S.; Palladino, K. J.; Pease, E. K.; Penning, B. P.; Pereira, G.; Piepke, A.; Pushkin, K.; Reichenbacher, J.; Rhyne, C. A.; Riffard, Q.; Rischbieter, G. R. C.; Rodrigues, J. P.; Rosero, R.; Rossiter, P.; Rutherford, G.; Sazzad, A. B. M. R.; Schnee, R. W.; Schubnell, M.; Scovell, P. R.; Seymour, D.; Shaw, S.; Shutt, T. A.; Silk, J. J.; Silva, C.; Solmaz, M.; Solovov, V. N.; Sorensen, P.; Stancu, I.; Stevens, A.; Stiegler, T. M.; Stifter, K.; Szydagis, M.; Taylor, W. C.; Taylor, R.; Temples, D.; Terman, P. A.; Tiedt, D. R.; Timalsina, M.; Tomás, A.; Tripathi, M.; Tvrznikova, L.; Utku, U.; Uvarov, S.; Vacheret, A.; Wang, J. J.; Watson, J. R.; Webb, R. C.; White, R. G.; Whitis, T. J.; Wolfs, F. L. H.; Woodward, D.; Yin, J.; Lux-Zeplin (Lz) Collaboration Bibcode: 2020APh...11602391A Altcode: 2019arXiv190402112A Deep underground environments are ideal for low background searches due to the attenuation of cosmic rays by passage through the earth. However, they are affected by backgrounds from γ-rays emitted by 40K and the 238U and 232Th decay chains in the surrounding rock. The LUX-ZEPLIN (LZ) experiment will search for dark matter particle interactions with a liquid xenon TPC located within the Davis campus at the Sanford Underground Research Facility, Lead, South Dakota, at the 4850-foot level. In order to characterise the cavern background, in-situ γ-ray measurements were taken with a sodium iodide detector in various locations and with lead shielding. The integral count rates (0-3300 keV) varied from 596 Hz to 1355 Hz for unshielded measurements, corresponding to a total flux from the cavern walls of 1.9 ± 0.4 γ cm-2s-1. The resulting activity in the walls of the cavern can be characterised as 220 ± 60 Bq/kg of 40K, 29 ± 15 Bq/kg of 238U, and 13 ± 3 Bq/kg of 232Th. Title: Exploring Flaring Behaviour on Low Mass Stars, Solar-type Stars and the Sun Authors: Doyle, L.; Ramsay, G.; Doyle, J. G.; Wyper, P. F.; Scullion, E.; Wu, K.; McLaughlin, J. A. Bibcode: 2020IAUS..354..384D Altcode: We report on our project to study the activity in both the Sun and low mass stars. Utilising high cadence, Hα observations of a filament eruption made using the CRISP spectropolarimeter mounted on the Swedish Solar Telescope has allowed us to determine 3D velocity maps of the event. To gain insight into the physical mechanism which drives the event we have qualitatively compared our observation to a 3D MHD reconnection model. Solar-type and low mass stars can be highly active producing flares with energies exceeding erg. Using K2 and TESS data we find no correlation between the number of flares and the rotation phase which is surprising. Our solar flare model can be used to aid our understanding of the origin of flares in other stars. By scaling up our solar model to replicate observed stellar flare energies, we investigate the conditions needed for such high energy flares. Title: Pan-STARRS Search for Kilonovae: discovery of PS19hgw, an intrinsically faint transient in KUG 0152+311 (144 Mpc) Authors: S; McLaughlin; Smartt, S. J.; Smith, K. W.; Chambers, K. C.; Huber, M.; Srivastav, S.; McBrien, O.; Young, D. R.; Gillanders, J.; O'Neill, D.; Clark, P.; Sim, S.; Boer, T. D.; Bulger, J.; Fairlamb, J.; Lin, C. C.; Lowe, T.; Magnier, E.; Schultz, A.; Wainscoat, R. J.; Willman, M.; Chen, T. W.; Wright, D. E.; Stubbs, C.; Rest, A. Bibcode: 2019TNSAN.154....1S Altcode: We are carrying out the "Pan-STARRS Search for Kilonovae" which is a focused search for intrinsically faint transients, or rapidly evolving transients in galaxies which are closer than 200 Mpc in the ongoing Pan-STARRS Near Earth Object surveys (see Smartt et al. AstroNote 2019-48 for details). Here we report the discovery of an intrinsically faint transient PS19hgw (AT2019wxt) in the host galaxy KUG 0152+311, at a redshift of z = 0.036, or d = 144 Mpc (from NED). It has an absolute magnitude at discovery of M_i = -16.6. We note that this is in the 80% contour of the skymap of the possible BNS gravitational wave source S191213g (the LALInference.fits.gz, The LIGO Scientific Collaboration and the Virgo Collaboration, GCN 26402), was discovered after the merger time, and is at a distance consistent with the parameter estimation of LVC for this event. Title: Observations and 3D Magnetohydrodynamic Modeling of a Confined Helical Jet Launched by a Filament Eruption Authors: Doyle, Lauren; Wyper, Peter F.; Scullion, Eamon; McLaughlin, James A.; Ramsay, Gavin; Doyle, J. Gerard Bibcode: 2019ApJ...887..246D Altcode: 2019arXiv191202133D We present a detailed analysis of a confined filament eruption and jet associated with a C1.5 class solar flare. Multi-wavelength observations from the Global Oscillations Network Group and Solar Dynamics Observatory reveal the filament forming over several days following the emergence and then partial cancellation of a minority polarity spot within a decaying bipolar active region. The emergence is also associated with the formation of a 3D null point separatrix that surrounds the minority polarity. The filament eruption occurs concurrently with brightenings adjacent to and below the filament, suggestive of breakout and flare reconnection, respectively. The erupting filament material becomes partially transferred into a strong outflow jet (∼60 km s-1) along coronal loops, becoming guided back toward the surface. Utilizing high-resolution Hα observations from the Swedish Solar Telescope/CRisp Imaging SpectroPolarimeter, we construct velocity maps of the outflows, demonstrating their highly structured but broadly helical nature. We contrast the observations with a 3D magnetohydrodynamic simulation of a breakout jet in a closed-field background and find close qualitative agreement. We conclude that the suggested model provides an intuitive mechanism for transferring twist/helicity in confined filament eruptions, thus validating the applicability of the breakout model not only to jets and coronal mass ejections but also to confined eruptions and flares. Title: A Blueprint of State-of-the-art Techniques for Detecting Quasi-periodic Pulsations in Solar and Stellar Flares Authors: Broomhall, Anne-Marie; Davenport, James R. A.; Hayes, Laura A.; Inglis, Andrew R.; Kolotkov, Dmitrii Y.; McLaughlin, James A.; Mehta, Tishtrya; Nakariakov, Valery M.; Notsu, Yuta; Pascoe, David J.; Pugh, Chloe E.; Van Doorsselaere, Tom Bibcode: 2019ApJS..244...44B Altcode: 2019arXiv191008458B Quasi-periodic pulsations (QPPs) appear to be a common feature observed in the light curves of both solar and stellar flares. However, their quasi-periodic nature, along with the fact that they can be small in amplitude and short-lived, makes QPPs difficult to unequivocally detect. In this paper, we test the strengths and limitations of state-of-the-art methods for detecting QPPs using a series of hare-and-hounds exercises. The hare simulated a set of flares, both with and without QPPs of a variety of forms, while the hounds attempted to detect QPPs in blind tests. We use the results of these exercises to create a blueprint for anyone who wishes to detect QPPs in real solar and stellar data. We present eight clear recommendations to be kept in mind for future QPP detections, with the plethora of solar and stellar flare data from new and future satellites. These recommendations address the key pitfalls in QPP detection, including detrending, trimming data, accounting for colored noise, detecting stationary-period QPPs, detecting QPPs with nonstationary periods, and ensuring that detections are robust and false detections are minimized. We find that QPPs can be detected reliably and robustly by a variety of methods, which are clearly identified and described, if the appropriate care and due diligence are taken. Title: The LUX-ZEPLIN (LZ) Experiment Authors: The LZ Collaboration; Akerib, D. S.; Akerlof, C. W.; Akimov, D. Yu.; Alquahtani, A.; Alsum, S. K.; Anderson, T. J.; Angelides, N.; Araújo, H. M.; Arbuckle, A.; Armstrong, J. E.; Arthurs, M.; Auyeung, H.; Bai, X.; Bailey, A. J.; Balajthy, J.; Balashov, S.; Bang, J.; Barry, M. J.; Barthel, J.; Bauer, D.; Bauer, P.; Baxter, A.; Belle, J.; Beltrame, P.; Bensinger, J.; Benson, T.; Bernard, E. P.; Bernstein, A.; Bhatti, A.; Biekert, A.; Biesiadzinski, T. P.; Birrittella, B.; Boast, K. E.; Bolozdynya, A. I.; Boulton, E. M.; Boxer, B.; Bramante, R.; Branson, S.; Brás, P.; Breidenbach, M.; Buckley, J. H.; Bugaev, V. V.; Bunker, R.; Burdin, S.; Busenitz, J. K.; Campbell, J. S.; Carels, C.; Carlsmith, D. L.; Carlson, B.; Carmona-Benitez, M. C.; Cascella, M.; Chan, C.; Cherwinka, J. J.; Chiller, A. A.; Chiller, C.; Chott, N. I.; Cole, A.; Coleman, J.; Colling, D.; Conley, R. A.; Cottle, A.; Coughlen, R.; Craddock, W. W.; Curran, D.; Currie, A.; Cutter, J. E.; da Cunha, J. P.; Dahl, C. E.; Dardin, S.; Dasu, S.; Davis, J.; Davison, T. J. R.; de Viveiros, L.; Decheine, N.; Dobi, A.; Dobson, J. E. Y.; Druszkiewicz, E.; Dushkin, A.; Edberg, T. K.; Edwards, W. R.; Edwards, B. N.; Edwards, J.; Elnimr, M. M.; Emmet, W. T.; Eriksen, S. R.; Faham, C. H.; Fan, A.; Fayer, S.; Fiorucci, S.; Flaecher, H.; Fogarty Florang, I. M.; Ford, P.; Francis, V. B.; Froborg, F.; Fruth, T.; Gaitskell, R. J.; Gantos, N. J.; Garcia, D.; Geffre, A.; Gehman, V. M.; Gelfand, R.; Genovesi, J.; Gerhard, R. M.; Ghag, C.; Gibson, E.; Gilchriese, M. G. D.; Gokhale, S.; Gomber, B.; Gonda, T. G.; Greenall, A.; Greenwood, S.; Gregerson, G.; van der Grinten, M. G. D.; Gwilliam, C. B.; Hall, C. R.; Hamilton, D.; Hans, S.; Hanzel, K.; Harrington, T.; Harrison, A.; Hasselkus, C.; Haselschwardt, S. J.; Hemer, D.; Hertel, S. A.; Heise, J.; Hillbrand, S.; Hitchcock, O.; Hjemfelt, C.; Hoff, M. D.; Holbrook, B.; Holtom, E.; Y-K. Hor, J.; Horn, M.; Huang, D. Q.; Hurteau, T. W.; Ignarra, C. M.; Irving, M. N.; Jacobsen, R. G.; Jahangir, O.; Jeffery, S. N.; Ji, W.; Johnson, M.; Johnson, J.; Johnson, P.; Jones, W. G.; Kaboth, A. C.; Kamaha, A.; Kamdin, K.; Kasey, V.; Kazkaz, K.; Keefner, J.; Khaitan, D.; Khaleeq, M.; Khazov, A.; Khromov, A. V.; Khurana, I.; Kim, Y. D.; Kim, W. T.; Kocher, C. D.; Konovalov, A. M.; Korley, L.; Korolkova, E. V.; Koyuncu, M.; Kras, J.; Kraus, H.; Kravitz, S. W.; Krebs, H. J.; Kreczko, L.; Krikler, B.; Kudryavtsev, V. A.; Kumpan, A. V.; Kyre, S.; Lambert, A. R.; Landerud, B.; Larsen, N. A.; Laundrie, A.; Leason, E. A.; Lee, H. S.; Lee, J.; Lee, C.; Lenardo, B. G.; Leonard, D. S.; Leonard, R.; Lesko, K. T.; Levy, C.; Li, J.; Liu, Y.; Liao, J.; Liao, F. -T.; Lin, J.; Lindote, A.; Linehan, R.; Lippincott, W. H.; Liu, R.; Liu, X.; Loniewski, C.; Lopes, M. I.; López Paredes, B.; Lorenzon, W.; Lucero, D.; Luitz, S.; Lyle, J. M.; Lynch, C.; Majewski, P. A.; Makkinje, J.; Malling, D. C.; Manalaysay, A.; Manenti, L.; Mannino, R. L.; Marangou, N.; Markley, D. J.; MarrLaundrie, P.; Martin, T. J.; Marzioni, M. F.; Maupin, C.; McConnell, C. T.; McKinsey, D. N.; McLaughlin, J.; Mei, D. -M.; Meng, Y.; Miller, E. H.; Minaker, Z. J.; Mizrachi, E.; Mock, J.; Molash, D.; Monte, A.; Monzani, M. E.; Morad, J. A.; Morrison, E.; Mount, B. J.; Murphy, A. St. J.; Naim, D.; Naylor, A.; Nedlik, C.; Nehrkorn, C.; Nelson, H. N.; Nesbit, J.; Neves, F.; Nikkel, J. A.; Nikoleyczik, J. A.; Nilima, A.; O'Dell, J.; Oh, H.; O'Neill, F. G.; O'Sullivan, K.; Olcina, I.; Olevitch, M. A.; Oliver-Mallory, K. C.; Oxborough, L.; Pagac, A.; Pagenkopf, D.; Pal, S.; Palladino, K. J.; Palmaccio, V. M.; Palmer, J.; Pangilinan, M.; Patton, S. J.; Pease, E. K.; Penning, B. P.; Pereira, G.; Pereira, C.; Peterson, I. B.; Piepke, A.; Pierson, S.; Powell, S.; Preece, R. M.; Pushkin, K.; Qie, Y.; Racine, M.; Ratcliff, B. N.; Reichenbacher, J.; Reichhart, L.; Rhyne, C. A.; Richards, A.; Riffard, Q.; Rischbieter, G. R. C.; Rodrigues, J. P.; Rose, H. J.; Rosero, R.; Rossiter, P.; Rucinski, R.; Rutherford, G.; Rynders, D.; Saba, J. S.; Sabarots, L.; Santone, D.; Sarychev, M.; Sazzad, A. B. M. R.; Schnee, R. W.; Schubnell, M.; Scovell, P. R.; Severson, M.; Seymour, D.; Shaw, S.; Shutt, G. W.; Shutt, T. A.; Silk, J. J.; Silva, C.; Skarpaas, K.; Skulski, W.; Smith, A. R.; Smith, R. J.; Smith, R. E.; So, J.; Solmaz, M.; Solovov, V. N.; Sorensen, P.; Sosnovtsev, V. V.; Stancu, I.; Stark, M. R.; Stephenson, S.; Stern, N.; Stevens, A.; Stiegler, T. M.; Stifter, K.; Studley, R.; Sumner, T. J.; Sundarnath, K.; Sutcliffe, P.; Swanson, N.; Szydagis, M.; Tan, M.; Taylor, W. C.; Taylor, R.; Taylor, D. J.; Temples, D.; Tennyson, B. P.; Terman, P. A.; Thomas, K. J.; Thomson, J. A.; Tiedt, D. R.; Timalsina, M.; To, W. H.; Tomás, A.; Tope, T. E.; Tripathi, M.; Tronstad, D. R.; Tull, C. E.; Turner, W.; Tvrznikova, L.; Utes, M.; Utku, U.; Uvarov, S.; Va'vra, J.; Vacheret, A.; Vaitkus, A.; Verbus, J. R.; Vietanen, T.; Voirin, E.; Vuosalo, C. O.; Walcott, S.; Waldron, W. L.; Walker, K.; Wang, J. J.; Wang, R.; Wang, L.; Wang, Y.; Watson, J. R.; Migneault, J.; Weatherly, S.; Webb, R. C.; Wei, W. -Z.; While, M.; White, R. G.; White, J. T.; White, D. T.; Whitis, T. J.; Wisniewski, W. J.; Wilson, K.; Witherell, M. S.; Wolfs, F. L. H.; Wolfs, J. D.; Woodward, D.; Worm, S. D.; Xiang, X.; Xiao, Q.; Xu, J.; Yeh, M.; Yin, J.; Young, I.; Zhang, C. Bibcode: 2019arXiv191009124T Altcode: We describe the design and assembly of the LUX-ZEPLIN experiment, a direct detection search for cosmic WIMP dark matter particles. The centerpiece of the experiment is a large liquid xenon time projection chamber sensitive to low energy nuclear recoils. Rejection of backgrounds is enhanced by a Xe skin veto detector and by a liquid scintillator Outer Detector loaded with gadolinium for efficient neutron capture and tagging. LZ is located in the Davis Cavern at the 4850' level of the Sanford Underground Research Facility in Lead, South Dakota, USA. We describe the major subsystems of the experiment and its key design features and requirements. Title: Exploring the Properties of Transverse Waves at the Base of the Solar Wind Authors: Weberg, Micah J.; Morton, Richard; McLaughlin, James; Laming, Martin; Ko, Yuan-Kuen Bibcode: 2019shin.confE.173W Altcode: Transverse (or ‘Alfvénic’) waves are commonly invoked by theories and models to explain coronal heating and solar wind acceleration. However, direct measurements are sparse and most of what we know is derived from indirect proxies for wave activity. In this study, we present a large, statistical study of transverse waves directly observed in coronal plumes between May 2010 and May 2019 by SDO / AIA. The data was processed using an automated version of the Northumbria University Wave Tracking Code (NUWT) and presents a detailed picture of wave properties at the base of the solar wind. We find that the bulk wave parameters within the time periods analysed are largely consistent over most of a solar cycle. However, there is some evidence for smaller-scale variations with height, latitude, and over time periods of a few years. We will also explore the possibility of frequency-dependant processes which may give limits on the height at which wave dissipation, and thereby solar wind acceleration, begins. Lastly, we will give estimates for the total energy flux contained in the waves and discuss how it compares to the energy required to accelerate the solar wind. Title: Damping of Propagating Kink Waves in the Solar Corona Authors: Tiwari, Ajay K.; Morton, Richard J.; Régnier, Stéphane; McLaughlin, James A. Bibcode: 2019ApJ...876..106T Altcode: 2019arXiv190408834T Alfvénic waves have gained renewed interest since the existence of ubiquitous propagating kink waves were discovered in the corona. It has long been suggested that Alfvénic waves play an important role in coronal heating and the acceleration of the solar wind. To this effect, it is imperative to understand the mechanisms that enable their energy to be transferred to the plasma. Mode conversion via resonant absorption is believed to be one of the main mechanisms for kink wave damping and it is considered to play a key role in the process of energy transfer. This study examines the damping of propagating kink waves in quiescent coronal loops using the Coronal Multi-channel Polarimeter. A coherence-based method is used to track the Doppler velocity signal of the waves, which enables us to investigate the spatial evolution of velocity perturbations. The power ratio of outward to inward propagating waves is used to estimate the associated damping lengths and quality factors. To enable accurate estimates of these quantities, we provide the first derivation of a likelihood function suitable for fitting models to the ratio of two power spectra obtained from discrete Fourier transforms. Maximum likelihood estimation is used to fit an exponential damping model to the observed variation in power ratio as a function of frequency. We confirm earlier indications that propagating kink waves are undergoing frequency-dependent damping. Additionally, we find that the rate of damping decreases, or equivalently the damping length increases, for longer coronal loops that reach higher in the corona. Title: 3D WKB solution for fast magnetoacoustic wave behaviour within a separatrix dome containing a coronal null point Authors: McLaughlin, James A.; Thurgood, Jonathan O.; Botha, Gert J. J.; Wiggs, Joshua A. Bibcode: 2019MNRAS.484.1390M Altcode: 2019MNRAS.tmp..133M The propagation of the fast magnetoacoustic wave is studied within a magnetic topology containing a 3D coronal null point whose fan field lines form a dome. The topology is constructed from a magnetic dipole embedded within a global uniform field. This study aims to improve the understanding of how magnetohydrodynamics (MHD) waves propagate through inhomogeneous media, specifically in a medium containing an isolated 3D magnetic null point. We consider the linearized MHD equations for an inhomogeneous, ideal, cold plasma. The equations are solved utilizing the WKB approximation and Charpit's Method. We find that for a planar fast wave generated below the null point, the resultant propagation is strongly dependent upon initial location and that there are two main behaviours: the majority of the wave escapes the null (experiencing different severities of refraction depending upon the interplay with the equilibrium Alfvén-speed profile) or, alternatively, part of the wave is captured by the coronal null point (for elements generated within a specific critical radius about the spine and on the z = 0 plane). We also generalize the magnetic topology and find that the height of the null determines the amount of wave that is captured. We conclude that for a wavefront generated below the null point, nulls at a greater height can trap proportionally less of the corresponding wave energy. Title: On the periodicity of linear and nonlinear oscillatory reconnection Authors: Thurgood, J. O.; Pontin, D. I.; McLaughlin, J. A. Bibcode: 2019A&A...621A.106T Altcode: 2018arXiv181108831T Context. An injection of energy towards a magnetic null point can drive reversals of current-sheet polarity leading to time-dependent, oscillatory reconnection (OR), which may explain periodic phenomena generated when reconnection occurs in the solar atmosphere. However, the details of what controls the period of these current-sheet oscillations in realistic systems is poorly understood, despite being of crucial importance in assessing whether a specific model of OR can account for observed periodic behaviour.
Aims: This paper aims to highlight that different types of reconnection reversal are supported about null points, and that these can be distinct from the oscillation in the closed-boundary, linear systems considered by a number of authors in the 1990s. In particular, we explore the features of a nonlinear oscillation local to the null point, and examine the effect of resistivity and perturbation energy on the period, contrasting it to the linear, closed-boundary case.
Methods: Numerical simulations of the single-fluid, resistive MHD equations are used to investigate the effects of plasma resistivity and perturbation energy upon the resulting OR.
Results: It is found that for small perturbations that behave linearly, the inverse Lundquist number dictates the period, provided the perturbation energy (i.e. the free energy) is small relative to the inverse Lundquist number defined on the boundary, regardless of the broadband structure of the initial perturbation. However, when the perturbation energy exceeds the threshold required for "nonlinear" null collapse to occur, a complex oscillation of the magnetic field is produced which is, at most, only weakly-dependent on the resistivity. The resultant periodicity is instead strongly influenced by the amount of free energy, with more energetic perturbations producing higher-frequency oscillations.
Conclusions: Crucially, with regards to typical solar-based and astrophysical-based input energies, we demonstrate that the majority far exceed the threshold for nonlinearity to develop. This substantially alters the properties and periodicity of both null collapse and subsequent OR. Therefore, nonlinear regimes of OR should be considered in solar and astrophysical contexts.

The movie associated to Fig. 3 is available at https://www.aanda.org Title: A basal contribution from p-modes to the Alfvénic wave flux in the Sun's corona Authors: Morton, R. J.; Weberg, M. J.; McLaughlin, J. A. Bibcode: 2019NatAs...3..223M Altcode: 2019arXiv190203811M; 2019NatAs.tmp..196M Many cool stars possess complex magnetic fields1 that are considered to undertake a central role in the structuring and energizing of their atmospheres2. Alfvénic waves are thought to make a critical contribution to energy transfer along these magnetic fields, with the potential to heat plasma and accelerate stellar winds3-5. Despite Alfvénic waves having been identified in the Sun's atmosphere, the nature of the basal wave energy flux is poorly understood. It is generally assumed that the associated Poynting flux is generated solely in the photosphere and propagates into the corona, typically through the continuous buffeting of magnetic fields by turbulent convective cells4,6,7. Here, we provide evidence that the Sun's internal acoustic modes also contribute to the basal flux of Alfvénic waves, delivering a spatially ubiquitous input to the coronal energy balance that is sustained over the solar cycle. Alfvénic waves are thus a fundamental feature of the Sun's corona. Acknowledging that internal acoustic modes have a key role in injecting additional Poynting flux into the upper atmospheres of Sun-like stars has potentially significant consequences for the modelling of stellar coronae and winds. Title: Predictions of DKIST/DL-NIRSP Observations for an Off-limb Kink-unstable Coronal Loop Authors: Snow, B.; Botha, G. J. J.; Scullion, E.; McLaughlin, J. A.; Young, P. R.; Jaeggli, S. A. Bibcode: 2018ApJ...863..172S Altcode: 2018arXiv180704972S Synthetic intensity maps are generated from a 3D kink-unstable flux rope simulation using several DKIST/DL-NIRSP spectral lines to make a prediction of the observational signatures of energy transport and release. The reconstructed large field-of-view intensity mosaics and single tile sit-and-stare high-cadence image sequences show detailed, fine-scale structure and exhibit signatures of wave propagation, redistribution of heat, flows, and fine-scale bursts. These fine-scale bursts are present in the synthetic Doppler velocity maps and can be interpreted as evidence for small-scale magnetic reconnection at the loop boundary. The spectral lines reveal the different thermodynamic structures of the loop, with the hotter lines showing the loop interior and braiding and the cooler lines showing the radial edges of the loop. The synthetic observations of DL-NIRSP are found to preserve the radial expansion, and hence the loop radius can be measured accurately. The electron number density can be estimated using the intensity ratio of the Fe XIII lines at 10747 and 10798 Å. The estimated density from this ratio is correct to within ±10% during the later phases of the evolution; however, it is less accurate initially when line-of-sight density inhomogeneities contribute to the Fe XIII intensity, resulting in an overprediction of the density by ≈30%. The identified signatures are all above a conservative estimate for instrument noise and therefore will be detectable. In summary, we have used forward modeling to demonstrate that the coronal off-limb mode of DKIST/DL-NIRSP will be able to detect multiple independent signatures of a kink-unstable loop and observe small-scale transient features including loop braiding/twisting and small-scale reconnection events occurring at the radial edge of the loop. Title: Resistively-limited current sheet implosions in planar anti-parallel (1D) and null-point containing (2D) magnetic field geometries Authors: Thurgood, Jonathan O.; Pontin, David I.; McLaughlin, James A. Bibcode: 2018PhPl...25g2105T Altcode: 2018arXiv180608157T Implosive formation of current sheets is a fundamental plasma process. Previous studies focused on the early time evolution, while here our primary aim is to explore the longer-term evolution, which may be critical for determining the efficiency of energy release. To address this problem, we investigate two closely related problems, namely: (i) 1D, pinched anti-parallel magnetic fields and (ii) 2D, null point containing fields which are locally imbalanced ("null-collapse" or "X-point collapse"). Within the framework of resistive MHD, we simulate the full nonlinear evolution through three distinct phases: the initial implosion, its eventual halting mechanism, and subsequent evolution post-halting. In a parameter study, we find that the scaling with resistivity of current sheet properties at the halting time is in good agreement—in both geometries—with that inferred from a known 1D similarity solution. We find that the halting of the implosions occurs rapidly after reaching the diffusion scale by sudden Ohmic heating of the dense plasma within the current sheet, which provides a pressure gradient sufficient to oppose further collapse and decelerate the converging flow. This back-pressure grows to exceed that required for force balance and so the post-implosion evolution is characterised by the consequences of the current sheet "bouncing" outwards. These are: (i) the launching of propagating fast MHD waves (shocks) outwards and (ii) the width-wise expansion of the current sheet itself. The expansion is only observed to stall in the 2D case, where the pressurisation is relieved by outflow in the reconnection jets. In the 2D case, we quantify the maximum amount of current sheet expansion as it scales with resistivity and analyse the structure of the reconnection region, which forms post-expansion, replete with Petschek-type slow shocks and fast termination shocks. Title: Implosive Collapse about Magnetic Null Points: A Quantitative Comparison between 2D and 3D Nulls Authors: Thurgood, Jonathan O.; Pontin, David I.; McLaughlin, James A. Bibcode: 2018ApJ...855...50T Altcode: 2018arXiv180207076T Null collapse is an implosive process whereby MHD waves focus their energy in the vicinity of a null point, forming a current sheet and initiating magnetic reconnection. We consider, for the first time, the case of collapsing 3D magnetic null points in nonlinear, resistive MHD using numerical simulation, exploring key physical aspects of the system as well as performing a detailed parameter study. We find that within a particular plane containing the 3D null, the plasma and current density enhancements resulting from the collapse are quantitatively and qualitatively as per the 2D case in both the linear and nonlinear collapse regimes. However, the scaling with resistivity of the 3D reconnection rate—which is a global quantity—is found to be less favorable when the magnetic null point is more rotationally symmetric, due to the action of increased magnetic back-pressure. Furthermore, we find that, with increasing ambient plasma pressure, the collapse can be throttled, as is the case for 2D nulls. We discuss this pressure-limiting in the context of fast reconnection in the solar atmosphere and suggest mechanisms by which it may be overcome. We also discuss the implications of the results in the context of null collapse as a trigger mechanism of Oscillatory Reconnection, a time-dependent reconnection mechanism, and also within the wider subject of wave-null point interactions. We conclude that, in general, increasingly rotationally asymmetric nulls will be more favorable in terms of magnetic energy release via null collapse than their more symmetric counterparts. Title: Modelling Quasi-Periodic Pulsations in Solar and Stellar Flares Authors: McLaughlin, J. A.; Nakariakov, V. M.; Dominique, M.; Jelínek, P.; Takasao, S. Bibcode: 2018SSRv..214...45M Altcode: 2018arXiv180204180M Solar flare emission is detected in all EM bands and variations in flux density of solar energetic particles. Often the EM radiation generated in solar and stellar flares shows a pronounced oscillatory pattern, with characteristic periods ranging from a fraction of a second to several minutes. These oscillations are referred to as quasi-periodic pulsations (QPPs), to emphasise that they often contain apparent amplitude and period modulation. We review the current understanding of quasi-periodic pulsations in solar and stellar flares. In particular, we focus on the possible physical mechanisms, with an emphasis on the underlying physics that generates the resultant range of periodicities. These physical mechanisms include MHD oscillations, self-oscillatory mechanisms, oscillatory reconnection/reconnection reversal, wave-driven reconnection, two loop coalescence, MHD flow over-stability, the equivalent LCR-contour mechanism, and thermal-dynamical cycles. We also provide a histogram of all QPP events published in the literature at this time. The occurrence of QPPs puts additional constraints on the interpretation and understanding of the fundamental processes operating in flares, e.g. magnetic energy liberation and particle acceleration. Therefore, a full understanding of QPPs is essential in order to work towards an integrated model of solar and stellar flares. Title: Onset of 2D magnetic reconnection in the solar photosphere, chromosphere, and corona Authors: Snow, B.; Botha, G. J. J.; McLaughlin, J. A.; Hillier, A. Bibcode: 2018A&A...609A.100S Altcode: 2017arXiv171100683S
Aims: We aim to investigate the onset of 2D time-dependent magnetic reconnection that is triggered using an external (non-local) velocity driver located away from, and perpendicular to, an equilibrium Harris current sheet. Previous studies have typically utilised an internal trigger to initiate reconnection, for example initial conditions centred on the current sheet. Here, an external driver allows for a more naturalistic trigger as well as the study of the earlier stages of the reconnection start-up process.
Methods: Numerical simulations solving the compressible, resistive magnetohydrodynamic (MHD) equations were performed to investigate the reconnection onset within different atmospheric layers of the Sun, namely the corona, chromosphere and photosphere.
Results: A reconnecting state is reached for all atmospheric heights considered, with the dominant physics being highly dependent on atmospheric conditions. The coronal case achieves a sharp rise in electric field (indicative of reconnection) for a range of velocity drivers. For the chromosphere, we find a larger velocity amplitude is required to trigger reconnection (compared to the corona). For the photospheric environment, the electric field is highly dependent on the inflow speed; a sharp increase in electric field is obtained only as the velocity entering the reconnection region approaches the Alfvén speed. Additionally, the role of ambipolar diffusion is investigated for the chromospheric case and we find that the ambipolar diffusion alters the structure of the current density in the inflow region.
Conclusions: The rate at which flux enters the reconnection region is controlled by the inflow velocity. This determines all aspects of the reconnection start-up process, that is, the early onset of reconnection is dominated by the advection term in Ohm's law in all atmospheric layers. A lower plasma-β enhances reconnection and creates a large change in the electric field. A high plasma-β hinders the reconnection, yielding a sharp rise in the electric field only when the velocity flowing into the reconnection region approaches the local Alfvén speed. Title: An Automated Algorithm for Identifying and Tracking Transverse Waves in Solar Images Authors: Weberg, Micah J.; Morton, Richard J.; McLaughlin, James A. Bibcode: 2018ApJ...852...57W Altcode: 2018arXiv180704842W Recent instrumentation has demonstrated that the solar atmosphere supports omnipresent transverse waves, which could play a key role in energizing the solar corona. Large-scale studies are required in order to build up an understanding of the general properties of these transverse waves. To help facilitate this, we present an automated algorithm for identifying and tracking features in solar images and extracting the wave properties of any observed transverse oscillations. We test and calibrate our algorithm using a set of synthetic data, which includes noise and rotational effects. The results indicate an accuracy of 1%-2% for displacement amplitudes and 4%-10% for wave periods and velocity amplitudes. We also apply the algorithm to data from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory and find good agreement with previous studies. Of note, we find that 35%-41% of the observed plumes exhibit multiple wave signatures, which indicates either the superposition of waves or multiple independent wave packets observed at different times within a single structure. The automated methods described in this paper represent a significant improvement on the speed and quality of direct measurements of transverse waves within the solar atmosphere. This algorithm unlocks a wide range of statistical studies that were previously impractical. Title: Annual Properties of Transverse Waves in the Corona over most of Solar Cycle 24 Authors: Weberg, M. J.; Morton, R. J.; McLaughlin, J. A. Bibcode: 2017AGUFMSH42B..07W Altcode: Waves are an omnipresent feature in heliophysical plasmas. In particular, transverse (or "Alfvénic") waves have been observed at a wide range of spatial and temporal scales within the corona and solar wind. These waves play a key role in transporting energy through the solar atmosphere and are also thought to contribute to the heating and acceleration of the solar wind. Previous studies of low-frequency (< 10 mHz) transverse waves in coronal loops and polar plumes have provided tantalizing glimpses at specific time periods, however few, if any, systematic studies have been performed spanning long time scales. In this study, we combine recent advancements in the automated detection and measurement of low-frequency transverse waves with over 7 years of SDO / AIA data to provide a detailed picture of coronal transverse waves in polar plumes and, for the first time, begin to examine their long-term behaviour. We measure waves at three different heights in each of eight, four-hour periods spanning May 2010 - May 2017. We find that the bulk wave parameters within these 24 regions are largely consistent over most of a solar cycle. However, there is some evidence for smaller-scale variations both with height and over time periods of a few years. We also discuss total energy flux estimations based on the full wave power spectra, which yields a more nuanced picture than previous values based on summary statistics. Overall, this work expands our view of wave processes in the corona and is relevant to both theoretical and modelling considerations of energy transport within the solar atmosphere. Crucially, these initial results suggest that the energy flux provided by the low-frequency transverse waves varies little over the solar cycle, potentially indicating that the waves provide a consistent source of energy to the corona and beyond. Title: Three-dimensional Oscillatory Reconnection Authors: Thurgood, Jonathan; Pontin, David; McLaughlin, James Bibcode: 2017shin.confE..88T Altcode: Here we detail the dynamic evolution of localised reconnection regions about three-dimensional (3D) magnetic null points by using numerical simulation. We demonstrate for the first time that reconnection triggered by the localised collapse of a 3D null point due to an external MHD wave involves a self-generated oscillation, whereby the current sheet and outflow jets undergo a reconnection reversal process during which back-pressure formation at the jet heads acts to prise open the collapsed field before overshooting the equilibrium into an opposite-polarity configuration. The discovery that reconnection at fully 3D nulls can proceed naturally in a time-dependent and periodic fashion is suggestive that oscillatory reconnection mechanisms may play a role in explaining periodicity in astrophysical phenomena associated with magnetic reconnection, such as the observed quasi-periodicity of solar and stellar flare emission. Furthermore, we find a consequence of oscillatory reconnection is the generation of a plethora of freely-propagating MHD waves which escape the vicinity of the reconnection region. Title: Three-dimensional Oscillatory Magnetic Reconnection Authors: Thurgood, Jonathan O.; Pontin, David I.; McLaughlin, James A. Bibcode: 2017ApJ...844....2T Altcode: 2017arXiv170609662T Here we detail the dynamic evolution of localized reconnection regions about 3D magnetic null points using numerical simulation. We demonstrate for the first time that reconnection triggered by the localized collapse of a 3D null point that is due to an external magnetohydrodynamic (MHD) wave involves a self-generated oscillation, whereby the current sheet and outflow jets undergo a reconnection reversal process during which back-pressure formation at the jet heads acts to prise open the collapsed field before overshooting the equilibrium into an opposite-polarity configuration. The discovery that reconnection at fully 3D nulls can proceed naturally in a time-dependent and periodic fashion suggests that oscillatory reconnection mechanisms may play a role in explaining periodicity in astrophysical phenomena associated with magnetic reconnection, such as the observed quasi-periodicity of solar and stellar flare emission. Furthermore, we find that a consequence of oscillatory reconnection is the generation of a plethora of freely propagating MHD waves that escape the vicinity of the reconnection region. Title: Project SunbYte: solar astronomy on a budget Authors: Alvarez Gonzalez, F.; Badilita, A. -M.; Baker, A.; Cho, Y. -H.; Dhot, N.; Fedun, V.; Hare, C.; He, T.; Hobbs, M.; Javed, M.; Lovesey, H.; Lord, C.; Panoutsos, G.; Permyakov, A.; Pope, S.; Portnell, M.; Rhodes, L.; Sharma, R.; Taras, P.; Taylor, J.; Tilbrook, R.; Verth, G.; Wrigley, S. N.; Yaqoob, M.; Cook, R.; McLaughlin, J.; Morton, R.; Scullion, E.; Shelyag, S.; Hamilton, A.; Zharkov, S.; Jess, D.; Wrigley, M. Bibcode: 2017A&G....58d2.24A Altcode: The Sheffield University Nova Balloon Lifted Solar Telescope (SunbYte) is a high-altitude balloon experiment devised and run largely by students at the University of Sheffield, and is scheduled for launch in October 2017. It was the only UK project in 2016 to be selected for the balloon side of the Swedish-German student programme REXUS/BEXUS (Rocket and Balloon Experiments for University Students; see box on p2.25). The success of the SunbYte team in the REXUS/BEXUS selection process is an unprecedented opportunity for the students to gain valuable experience working in the space engineering industry, using their theoretical knowledge and networking with students and technology companies from all over Europe. Title: Erosion and Basin Modification of Smaller Complex Craters in the Isidis Region, Mars Authors: McLaughlin, J. A.; Davatzes, A. K. Bibcode: 2017LPI....48.1190M Altcode: Trends of features found / In martian crater basins / Rim degradation. Title: Automating Direct Observations of Transverse Waves in the Solar Corona Authors: Weberg, M. J.; Morton, R. J.; McLaughlin, J. A. Bibcode: 2016AGUFMSH21E2576W Altcode: A multitude of MHD waves have been observed at a large range of scales in the solar atmosphere. According to theories and models, transverse (or "Alfvénic") waves are a viable mechanism for both heating and accelerating the solar wind and may also drive certain elemental fractionation processes in the chromosphere and corona. However, direct measurements of transverse waves in polar plumes (Thurgood et al. 2014) have raised some questions concerning the total energy carried by the waves and whether or not it is sufficient to be a primary driver of either solar wind heating or acceleration. In this work we build upon on the framework of Morton & McLaughlin (2013) and Thurgood et al. (2014) and extend the capabilities of the Northumbria University Wave Tracking (NUWT) code. In particular, we present an automated method of detecting and quantifying transverse waves in polar coronal holes. With the application of Fourier analysis methods, we investigate the superposition of multiple waves propagating along individual structures and, additionally, examine multi-variate relationships that may exist between wave parameters. We report the distributions of wave parameters for hundreds of waves observed using data from the 171 Å channel of SDO / AIA at select times throughout the solar cycle. Finally, we discuss how the measured average wave energy compares to theoretical predictions. The methods described in this research can be easily applied to other instruments, both space- and ground-based, and the observations of wave parameters and energetics place important constraints on wave-driven models of the solar corona. Title: Exploring Coronal Dynamics: A Next Generation Solar Physics Mission white paper Authors: Morton, R. J.; Scullion, E.; Bloomfield, D. S.; McLaughlin, J. A.; Regnier, S.; McIntosh, S. W.; Tomczyk, S.; Young, P. Bibcode: 2016arXiv161106149M Altcode: Determining the mechanisms responsible for the heating of the coronal plasma and maintaining and accelerating the solar wind are long standing goals in solar physics. There is a clear need to constrain the energy, mass and momentum flux through the solar corona and advance our knowledge of the physical process contributing to these fluxes. Furthermore, the accurate forecasting of Space Weather conditions at the near-Earth environment and, more generally, the plasma conditions of the solar wind throughout the heliosphere, require detailed knowledge of these fluxes in the near-Sun corona. Here we present a short case for a space-based imaging-spectrometer coronagraph, which will have the ability to provide synoptic information on the coronal environment and provide strict constraints on the mass, energy, and momentum flux through the corona. The instrument would ideally achieve cadences of $\sim10$~s, spatial resolution of 1" and observe the corona out to 2~$R_{\sun}$. Such an instrument will enable significant progress in our understanding of MHD waves throughout complex plasmas, as well as potentially providing routine data products to aid Space Weather forecasting. Title: 3D WKB solution for fast magnetoacoustic wave behaviour around an X-line Authors: McLaughlin, J. A.; Botha, G. J. J.; Régnier, S.; Spoors, D. L. Bibcode: 2016A&A...591A.103M Altcode: 2016arXiv160702379M Context. We study the propagation of a fast magnetoacoustic wave in a 3D magnetic field created from two magnetic dipoles. The magnetic topology contains an X-line.
Aims: We aim to contribute to the overall understanding of MHD wave propagation within inhomogeneous media, specifically around X-lines.
Methods: We investigate the linearised, 3D MHD equations under the assumptions of ideal and cold plasma. We utilise the WKB approximation and Charpit's method during our investigation.
Results: It is found that the behaviour of the fast magnetoacoustic wave is entirely dictated by the local, inhomogeneous, equilibrium Alfvén speed profile. All parts of the wave experience refraction during propagation, where the magnitude of the refraction effect depends on the location of an individual wave element within the inhomogeneous magnetic field. The X-line, along which the Alfvén speed is identically zero, acts as a focus for the refraction effect. There are two main types of wave behaviour: part of the wave is either trapped by the X-line or escapes the system, and there exists a critical starting region around the X-line that divides these two types of behaviour. For the set-up investigated, it is found that 15.5% of the fast wave energy is trapped by the X-line.
Conclusions: We conclude that linear, β = 0 fast magnetoacoustic waves can accumulate along X-lines and thus these will be specific locations of fast wave energy deposition and thus preferential heating. The work here highlights the importance of understanding the magnetic topology of a system. We also demonstrate how the 3D WKB technique described in this paper can be applied to other magnetic configurations. Title: Nuwt: Northumbria University Wave Tracking (Nuwt) Code Authors: Morton, Richard J.; Mooroogen, Krishna; McLaughlin, James A. Bibcode: 2016zndo.....49563M Altcode: This is the first release of the Northumbria University Wave Tracking (NUWT) code (in IDL). The code is primarily designed to analyse transverse waves along curvilinear features in solar imaging data, however, the underlying operations will work on any images. Tutorials and videos are included with the release. Title: Behaviour of Magnetoacoustic Waves in the Neighbourhood of a Two-Dimensional Null Point: Initially Cylindrically Symmetric Perturbations Authors: McLaughlin, J. A. Bibcode: 2016JApA...37....2M Altcode: 2016arXiv160702363M The propagation of magnetoacoustic waves in the neighbourhood of a 2D null point is investigated for both β=0 and β ≠ 0 plasmas. Previous work has shown that the Alfvén speed, here v A ∝ r, plays a vital role in such systems and so a natural choice is to switch to polar coordinates. For β=0 plasma, we derive an analytical solution for the behaviour of the fast magnetoacoustic wave in terms of the Klein-Gordon equation. We also solve the system with a semi-analytical WKB approximation which shows that the β=0 wave focuses on the null and contracts around it but, due to exponential decay, never reaches the null in a finite time. For the β ≠ 0 plasma, we solve the system numerically and find the behaviour to be similar to that of the β=0 system at large radii, but completely different close to the null. We show that for an initially cylindrically-symmetric fast magnetoacoustic wave perturbation, there is a decrease in wave speed along the separatrices and so the perturbation starts to take on a quasi-diamond shape; with the corners located along the separatrices. This is due to the growth in pressure gradients that reach a maximum along the separatrices, which in turn reduces the acceleration of the fast wave along the separatrices leading to a deformation of the wave morphology. Title: First Direct Measurements of Transverse Waves in Solar Polar Plumes Using SDO/AIA Authors: Thurgood, J. O.; Morton, R. J.; McLaughlin, J. A. Bibcode: 2014ApJ...790L...2T Altcode: 2014arXiv1406.5348T There is intense interest in determining the precise contribution of Alfvénic waves propagating along solar structures to the problems of coronal heating and solar wind acceleration. Since the launch of SDO/AIA, it has been possible to resolve transverse oscillations in off-limb solar polar plumes and recently McIntosh et al. concluded that such waves are energetic enough to play a role in heating the corona and accelerating the fast solar wind. However, this result is based on comparisons to Monte Carlo simulations and confirmation via direct measurements is still outstanding. Thus, this Letter reports on the first direct measurements of transverse wave motions in solar polar plumes. Over a four hour period, we measure the transverse displacements, periods, and velocity amplitudes of 596 distinct oscillations observed in the 171 Å channel of SDO/AIA. We find a broad range of non-uniformly distributed parameter values which are well described by log-normal distributions with peaks at 234 km, 121 s, and 8 km s-1, and mean and standard deviations of 407 ± 297 km, 173 ± 118 s, and 14 ± 10 km s-1. Within standard deviations, our direct measurements are broadly consistent with previous results. However, accounting for the whole of our observed non-uniform parameter distribution we calculate an energy flux of 9-24 W m-2, which is 4-10 times below the energy requirement for solar wind acceleration. Hence, our results indicate that transverse magnetohydrodynamic waves as resolved by SDO/AIA cannot be the dominant energy source for fast solar wind acceleration in the open-field corona. Title: High-resolution Observations of Active Region Moss and its Dynamics Authors: Morton, R. J.; McLaughlin, J. A. Bibcode: 2014ApJ...789..105M Altcode: 2014arXiv1405.5694M The High Resolution Coronal Imager has provided the sharpest view of the EUV corona to date. In this paper, we exploit its impressive resolving power to provide the first analysis of the fine-scale structure of moss in an active region. The data reveal that the moss is made up of a collection of fine threads that have widths with a mean and standard deviation of 440 ± 190 km (FWHM). The brightest moss emission is located at the visible head of the fine-scale structure and the fine structure appears to extend into the lower solar atmosphere. The emission decreases along the features, implying that the lower sections are most likely dominated by cooler transition region plasma. These threads appear to be the cool, lower legs of the hot loops. In addition, the increased resolution allows for the first direct observation of physical displacements of the moss fine structure in a direction transverse to its central axis. Some of these transverse displacements demonstrate periodic behavior, which we interpret as a signature of kink (Alfvénic) waves. Measurements of the properties of the transverse motions are made and the wave motions have means and standard deviations of 55 ± 37 km for the transverse displacement amplitude, 77 ± 33 s for the period, and 4.7 ± 2.5 km s-1 for the velocity amplitude. The presence of waves in the transition region of hot loops could have important implications for the heating of active regions. Title: High-resolution observations of active region moss and its dynamics Authors: Morton, Richard; McLaughlin, James Bibcode: 2014cosp...40E2181M Altcode: The High resolution Coronal Imager (Hi-C) has provided the sharpest view of the EUV corona to date. I will present results that exploit its impressive resolving power to provide the first analysis of the fine-scale structure of moss in an active region. The data reveal that the moss is made up of a collection of fine threads that have widths ranging between 400-1000 km. These fine-scale structures are connected to the bright moss and appear to extend into the lower solar atmosphere. The emission decreases along the features implying the lower sections are most likely dominated by cooler transition region plasma. These threads appear to be the cool, lower legs of the hot loops. The increased resolution also allows for the first direct observation of physical displacements of the moss fine-structure in a direction transverse to its central axis. Some of these transverse displacements demonstrate periodic behaviour, which we interpret as a signature of kink (Alfvénic) waves. The presence of waves in the transition region of hot loops could have important implications for the heating of active regions. Title: On Ponderomotive Effects Induced by Alfvén Waves in Inhomogeneous 2.5D MHD Plasmas Authors: Thurgood, J. O.; McLaughlin, J. A. Bibcode: 2013SoPh..288..205T Altcode: 2013arXiv1302.4340T Where spatial gradients in the amplitude of an Alfvén wave are non-zero, a nonlinear magnetic-pressure gradient acts upon the medium (commonly referred to as the ponderomotive force). We investigate the nature of such a force in inhomogeneous 2.5D MHD plasmas by analysing source terms in the nonlinear wave equations for the general case of inhomogeneous B and ρ, and consider supporting nonlinear numerical simulations. Our equations indicate that there are two distinct classes of ponderomotive effect induced by Alfvén waves in general 2.5D MHD, each with both a longitudinal and transverse manifestation. i) Geometric effects: Gradients in the pulse geometry relative to the background magnetic field cause the wave to sustain cospatial disturbances, the longitudinal and transverse daughter disturbances - where we report on the transverse disturbance for the first time. ii) ∇(cA) effects: Where a pulse propagates through an inhomogeneous region (where the gradients in the Alfvén-speed profile cA are non-zero), the nonlinear magnetic-pressure gradient acts to accelerate the plasma. Transverse gradients (phase mixing regions) excite independently propagating fast magnetoacoustic waves (generalising the result of Nakariakov, Roberts, and Murawski (Solar Phys.175, 93, 1997)) and longitudinal gradients (longitudinally dispersive regions) perturb along the field (thus creating static disturbances in β=0, and slow waves in β≠0). We additionally demonstrate that mode conversion due the nonlinear Lorentz force is a one-way process, and does not act as a mechanism to nonlinearly generate Alfvén waves due to propagating magnetoacoustic waves. We conclude that these ponderomotive effects are induced by an Alfvén wave propagating in any MHD medium, and have the potential to have significant consequences on the dynamics of energy transport and aspects of dissipation provided the system is sufficiently nonlinear and inhomogeneous. Title: 3D Alfvén wave behaviour about proper and improper magnetic null points Authors: Thurgood, J. O.; McLaughlin, J. A. Bibcode: 2013A&A...558A.127T Altcode: 2013arXiv1307.7001T Context. Magnetohydrodynamic (MHD) waves and magnetic null points are both prevalent in many astrophysical plasmas, including the solar atmosphere. Interaction between waves and null points has been implicated as a possible mechanism for localised heating events.
Aims: Here we investigate the transient behaviour of the Alfvén wave about fully 3D proper and improper magnetic null points.
Methods: We introduce an Alfvén wave into the vicinity of both proper and improper null points by numerically solving the ideal, β = 0 MHD equations using the LARE3D code. A magnetic fieldline and flux-based coordinate system permits the isolation of resulting wave modes and the analysis of their interaction.
Results: We find that the Alfvén wave propagates throughout the region and accumulates near the fan-plane, causing current build up. For different values of null point eccentricity, the qualitative behaviour changes only by the imposition of anisotropic pulse dilation, owing to the differing rates at which fieldlines diverge from the spine. For all eccentricities, we find that the fast and Alfvén waves are linearly decoupled. During the driving phase, an independently propagating fast wave is nonlinearly generated owing to the ponderomotive force. Subsequently, no further excitation of fast waves occurs.
Conclusions: We find that the key aspects of the theory of Alfvén waves about 2D null points extends intuitively to the fully 3D case; i.e. the wave propagates along fieldlines and thus accumulates at predictable parts of the topology. We also highlight that unlike in the 2D case, in 3D Alfvén-wave pulses are always toroidal, and thus any aspects of 2D Alfvén-wave-null models that are pulse-geometry specific must be reconsidered in 3D. Title: Phase Mixing of Alfvén Waves Near a 2D Magnetic Null Point Authors: McLaughlin, J. A. Bibcode: 2013JApA...34..223M Altcode: 2014arXiv1407.1743M; 2013JApA..tmp...23M The propagation of linear Alfvén wave pulses in an inhomogeneous plasma near a 2D coronal null point is investigated. When a uniform plasma density is considered, it is seen that an initially planar Alfvén wavefront remains planar, despite the varying equilibrium Alfvén speed, and that all the wave collects at the separatrices. Thus, in the non-ideal case, these Alfvénic disturbances preferentially dissipate their energy at these locations. For a non-uniform equilibrium density, it is found that the Alfvén wavefront is significantly distorted away from the initially planar geometry, inviting the possibility of dissipation due to phase mixing. Despite this however, we conclude that for the Alfvén wave, current density accumulation and preferential heating still primarily occur at the separatrices, even when an extremely non-uniform density profile is considered. Title: Hi-C and AIA observations of transverse magnetohydrodynamic waves in active regions (Corrigendum) Authors: Morton, R. J.; McLaughlin, J. A. Bibcode: 2013A&A...556C...1M Altcode: No abstract at ADS Title: Non-symmetric magnetohydrostatic equilibria: a multigrid approach Authors: MacTaggart, D.; Elsheikh, A.; McLaughlin, J. A.; Simitev, R. D. Bibcode: 2013A&A...556A..40M Altcode: 2013arXiv1307.6720M
Aims: Linear magnetohydrostatic (MHS) models of solar magnetic fields balance plasma pressure gradients, gravity and Lorentz forces where the current density is composed of a linear force-free component and a cross-field component that depends on gravitational stratification. In this paper, we investigate an efficient numerical procedure for calculating such equilibria.
Methods: The MHS equations are reduced to two scalar elliptic equations - one on the lower boundary and the other within the interior of the computational domain. The normal component of the magnetic field is prescribed on the lower boundary and a multigrid method is applied on both this boundary and within the domain to find the poloidal scalar potential. Once solved to a desired accuracy, the magnetic field, plasma pressure and density are found using a finite difference method.
Results: We investigate the effects of the cross-field currents on the linear MHS equilibria. Force-free and non-force-free examples are given to demonstrate the numerical scheme and an analysis of speed-up due to parallelization on a graphics processing unit (GPU) is presented. It is shown that speed-ups of ×30 are readily achievable. Title: Nonlinear Alfvén wave dynamics at a 2D magnetic null point: ponderomotive force Authors: Thurgood, J. O.; McLaughlin, J. A. Bibcode: 2013A&A...555A..86T Altcode: 2013arXiv1305.7073T Context. In the linear, β = 0 MHD regime, the transient properties of magnetohydrodynamic (MHD) waves in the vicinity of 2D null points are well known. The waves are decoupled and accumulate at predictable parts of the magnetic topology: fast waves accumulate at the null point; whereas Alfvén waves cannot cross the separatricies. However, in nonlinear MHD mode conversion can occur at regions of inhomogeneous Alfvén speed, suggesting that the decoupled nature of waves may not extend to the nonlinear regime.
Aims: We investigate the behaviour of low-amplitude Alfvén waves about a 2D magnetic null point in nonlinear, β = 0 MHD.
Methods: We numerically simulate the introduction of low-amplitude Alfvén waves into the vicinity of a magnetic null point using the nonlinear LARE2D code.
Results: Unlike in the linear regime, we find that the Alfvén wave sustains cospatial daughter disturbances, manifest in the transverse and longitudinal fluid velocity, owing to the action of nonlinear magnetic pressure gradients (viz. the ponderomotive force). These disturbances are dependent on the Alfvén wave and do not interact with the medium to excite magnetoacoustic waves, although the transverse daughter becomes focused at the null point. Additionally, an independently propagating fast magnetoacoustic wave is generated during the early stages, which transports some of the initial Alfvén wave energy towards the null point. Subsequently, despite undergoing dispersion and phase-mixing due to gradients in the Alfvén-speed profile (∇cA ≠ 0) there is no further nonlinear generation of fast waves.
Conclusions: We find that Alfvén waves at 2D cold null points behave largely as in the linear regime, however they sustain transverse and longitudinal disturbances - effects absent in the linear regime - due to nonlinear magnetic pressure gradients. Title: Hi-C and AIA observations of transverse magnetohydrodynamic waves in active regions Authors: Morton, R. J.; McLaughlin, J. A. Bibcode: 2013A&A...553L..10M Altcode: 2013arXiv1305.0140M The recent launch of the High resolution Coronal imager (Hi-C) provided a unique opportunity of studying the EUV corona with unprecedented spatial resolution. We utilize these observations to investigate the properties of low-frequency (50-200 s) active region transverse waves, whose omnipresence had been suggested previously. The five-fold improvement in spatial resolution over SDO/AIA reveals coronal loops with widths 150-310 km and that these loops support transverse waves with displacement amplitudes <50 km. However, the results suggest that wave activity in the coronal loops is of low energy, with typical velocity amplitudes <3 km s-1. An extended time-series of SDO data suggests that low-energy wave behaviour is typical of the coronal structures both before and after the Hi-C observations.

Appendix A and five movies associated to Figs. A.2-A.6 are available in electronic form at http://www.aanda.org Title: Numerical Simulations of Magnetoacoustic-Gravity Waves in the Solar Atmosphere Authors: Murawski, K.; Srivastava, A. K.; McLaughlin, J. A.; Oliver, R. Bibcode: 2013SoPh..283..383M Altcode: 2012SoPh..tmp..328M; 2012arXiv1208.5837M We investigate the excitation of magnetoacoustic-gravity waves generated from localized pulses in the gas pressure as well as in the vertical component of velocity. These pulses are initially launched at the top of the solar photosphere, which is permeated by a weak magnetic field. We investigate three different configurations of the background magnetic field lines: horizontal, vertical, and oblique to the gravitational force. We numerically model magnetoacoustic-gravity waves by implementing a realistic (VAL-C) model of the solar temperature. We solve the two-dimensional ideal magnetohydrodynamic equations numerically with the use of the FLASH code to simulate the dynamics of the lower solar atmosphere. The initial pulses result in shocks at higher altitudes. Our numerical simulations reveal that a small-amplitude initial pulse can produce magnetoacoustic-gravity waves, which are later reflected from the transition region due to the large-temperature gradient. The cavities in the lower solar atmosphere are found to have the best conditions to act as a resonator for various oscillations, including their trapping and leakage into the higher atmosphere. Our numerical simulations successfully model the excitation of such wave modes, their reflection and trapping, as well as the associated plasma dynamics. Title: On the periodicity of oscillatory reconnection Authors: McLaughlin, J. A.; Thurgood, J. O.; MacTaggart, D. Bibcode: 2012A&A...548A..98M Altcode: 2012arXiv1212.1000M Context. Oscillatory reconnection is a time-dependent magnetic reconnection mechanism that naturally produces periodic outputs from aperiodic drivers.
Aims: This paper aims to quantify and measure the periodic nature of oscillatory reconnection for the first time.
Methods: We solve the compressible, resistive, nonlinear magnetohydrodynamics (MHD) equations using 2.5D numerical simulations.
Results: We identify two distinct periodic regimes: the impulsive and stationary phases. In the impulsive phase, we find the greater the amplitude of the initial velocity driver, the longer the resultant current sheet and the earlier its formation. In the stationary phase, we find that the oscillations are exponentially decaying and for driving amplitudes 6.3-126.2 km s-1, we measure stationary-phase periods in the range 56.3-78.9 s, i.e. these are high frequency (0.01-0.02 Hz) oscillations. In both phases, we find that the greater the amplitude of the initial velocity driver, the shorter the resultant period, but note that different physical processes and periods are associated with both phases.
Conclusions: We conclude that the oscillatory reconnection mechanism behaves akin to a damped harmonic oscillator. Title: Linear and nonlinear MHD mode coupling of the fast magnetoacoustic wave about a 3D magnetic null point Authors: Thurgood, J. O.; McLaughlin, J. A. Bibcode: 2012A&A...545A...9T Altcode: 2012arXiv1208.5885T Context. Coronal magnetic null points have been implicated as possible locations for localised heating events in 2D models. We investigate this possibility about fully 3D null points.
Aims: We investigate the nature of the fast magnetoacoustic wave about a fully 3D magnetic null point, with a specific interest in its propagation, and we look for evidence of MHD mode coupling and/or conversion to the Alfvén mode.
Methods: A special fieldline and flux-based coordinate system was constructed to permit the introduction of a pure fast magnetoacoustic wave in the vicinity of proper and improper 3D null points. We considered the ideal, β = 0, MHD equations, which are solved using the LARE3D numerical code. The constituent modes of the resulting wave were isolated and identified using the special coordinate system. Numerical results were supported by analytical work derived from perturbation theory and a linear implementation of the WKB method.
Results: An initially pure fast wave is found to be permanently decoupled from the Alfvén mode both linearly and nonlinearly for both proper and improper 3D null points. The pure fast mode also generates and sustains a nonlinear disturbance aligned along the equilibrium magnetic field. The resulting pure fast magnetoacoustic pulse has transient behaviour, which is found to be governed by the (equilibrium) Alfvén-speed profile, and a refraction effect focuses all the wave energy towards the null point.
Conclusions: Thus, the main results from previous 2D work do indeed carry over to the fully 3D magnetic null points and so we conclude that 3D null points are locations for preferential heating in the corona by 3D fast magnetoacoustic waves. Title: Generation of Quasi-periodic Waves and Flows in the Solar Atmosphere by Oscillatory Reconnection Authors: McLaughlin, J. A.; Verth, G.; Fedun, V.; Erdélyi, R. Bibcode: 2012ApJ...749...30M Altcode: 2012arXiv1203.6846M We investigate the long-term evolution of an initially buoyant magnetic flux tube emerging into a gravitationally stratified coronal hole environment and report on the resulting oscillations and outflows. We perform 2.5-dimensional nonlinear numerical simulations, generalizing the models of McLaughlin et al. and Murray et al. We find that the physical mechanism of oscillatory reconnection naturally generates quasi-periodic vertical outflows, with a transverse/swaying aspect. The vertical outflows consist of both a periodic aspect and evidence of a positively directed flow. The speed of the vertical outflow (20-60 km s-1) is comparable to those reported in the observational literature. We also perform a parametric study varying the magnetic strength of the buoyant flux tube and find a range of associated periodicities: 1.75-3.5 minutes. Thus, the mechanism of oscillatory reconnection may provide a physical explanation to some of the high-speed, quasi-periodic, transverse outflows/jets recently reported by a multitude of authors and instruments. Title: Determination of Sub-resolution Structure of a Jet by Solar Magnetoseismology Authors: Morton, R. J.; Verth, G.; McLaughlin, J. A.; Erdélyi, R. Bibcode: 2012ApJ...744....5M Altcode: 2011arXiv1109.4851M A thin dark thread is observed in a UV/EUV solar jet in the 171 Å, 193 Å, and 211 Å, and partially in 304 Å. The dark thread appears to originate in the chromosphere but its temperature does not appear to lie within the passbands of the Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory. We therefore implement solar magnetoseismology to estimate the plasma parameters of the dark thread. A propagating kink (transverse) wave is observed to travel along the dark thread. The wave is tracked over a range of ~7000 km by placing multiple slits along the axis of the dark thread. The phase speed and amplitude of the wave are estimated and magnetoseismological theory is employed to determine the plasma parameters. We are able to estimate the plasma temperature, density gradient, magnetic field gradient, and sub-resolution expansion of the dark thread. The dark thread is found to be cool, T <~ 3 × 104, with both strong density and magnetic field gradients. The expansion of the flux tube along its length is ~300-400 km. Title: Review Article: MHD Wave Propagation Near Coronal Null Points of Magnetic Fields Authors: McLaughlin, J. A.; Hood, A. W.; de Moortel, I. Bibcode: 2011SSRv..158..205M Altcode: 2010SSRv..tmp..174M; 2010arXiv1004.5568M; 2010SSRv..tmp..157M We present a comprehensive review of MHD wave behaviour in the neighbourhood of coronal null points: locations where the magnetic field, and hence the local Alfvén speed, is zero. The behaviour of all three MHD wave modes, i.e. the Alfvén wave and the fast and slow magnetoacoustic waves, has been investigated in the neighbourhood of 2D, 2.5D and (to a certain extent) 3D magnetic null points, for a variety of assumptions, configurations and geometries. In general, it is found that the fast magnetoacoustic wave behaviour is dictated by the Alfvén-speed profile. In a β=0 plasma, the fast wave is focused towards the null point by a refraction effect and all the wave energy, and thus current density, accumulates close to the null point. Thus, null points will be locations for preferential heating by fast waves. Independently, the Alfvén wave is found to propagate along magnetic fieldlines and is confined to the fieldlines it is generated on. As the wave approaches the null point, it spreads out due to the diverging fieldlines. Eventually, the Alfvén wave accumulates along the separatrices (in 2D) or along the spine or fan-plane (in 3D). Hence, Alfvén wave energy will be preferentially dissipated at these locations. It is clear that the magnetic field plays a fundamental role in the propagation and properties of MHD waves in the neighbourhood of coronal null points. This topic is a fundamental plasma process and results so far have also lead to critical insights into reconnection, mode-coupling, quasi-periodic pulsations and phase-mixing. Title: Phase mixing of nonlinear visco-resistive Alfvén waves Authors: McLaughlin, J. A.; de Moortel, I.; Hood, A. W. Bibcode: 2011A&A...527A.149M Altcode: 2011arXiv1101.5945M
Aims: We investigate the behaviour of nonlinear, nonideal Alfvén wave propagation within an inhomogeneous magnetic environment.
Methods: The governing MHD equations are solved in 1D and 2D using both analytical techniques and numerical simulations.
Results: We find clear evidence for the ponderomotive effect and visco-resistive heating. The ponderomotive effect generates a longitudinal component to the transverse Alfvén wave, with a frequency twice that of the driving frequency. Analytical work shows the addition of resistive heating. This leads to a substantial increase in the local temperature and thus gas pressure of the plasma, resulting in material being pushed along the magnetic field. In 2D, our system exhibits phase mixing and we observe an evolution in the location of the maximum heating, i.e. we find a drifting of the heating layer.
Conclusions: Considering Alfvén wave propagation in 2D with an inhomogeneous density gradient, we find that the equilibrium density profile is significantly modified by both the flow of density due to visco-resistive heating and the nonlinear response to the localised heating through phase mixing. Title: A finite-difference algorithm for full waveform teleseismic tomography Authors: Roecker, S.; Baker, B.; McLaughlin, J. Bibcode: 2010GeoJI.181.1017R Altcode: We adapt a 2-D spectral domain finite difference waveform tomography algorithm previously used in active source seismological imaging to the case of a plane wave propagating through a 2.5-D viscoelastic medium in order to recover P and S wave speed variations from body waves recorded at teleseismic distances. A transferable efficacy that permits recovery of arbitrarily heterogenous models on moderately sized computers provides the primary motivation for choosing this algorithm. Synthetic waveforms can be generated either by specifying an analytic solution for a background plane wave in a 1-D model and solving for the source distribution that would produce it, or by solving for a scattered field excited by a plane wave source and then adding the background wavefield to it. Because the former approach typically involves a concentration of sources at the free surface, the latter tends to be more stable numerically. We adapt a gradient approach to solve the inverse problem to maintain tractability; calculating the gradient does not require much more computational effort than does the forward problem. The waveform tomography algorithm can be applied in a straightforward way to perform receiver function migration and traveltime inversion. Title: Impulsively generated oscillations in a 3D coronal loop Authors: Pascoe, D. J.; de Moortel, I.; McLaughlin, J. A. Bibcode: 2009A&A...505..319P Altcode: Aims: The effect of changing the attack angle for the interaction of a fast MHD wave with a 3D coronal loop is studied, to investigate to what extent the properties of the excited transverse kink mode oscillations of the loop depend on this angle.
Methods: 3D numerical simulations are performed of the interaction of a fast MHD wave, generated by a pressure pulse, with a 3D coronal loop. The loop itself is modelled as a density enhancement (with a finite plasma beta) within a magnetic arcade. The initial pressure pulse has a width comparable to the loop diameter and is situated outside of the loop, at the same height as the loop apex. This height is kept fixed but the (horizontal) angle between the pressure pulse and the loop is varied.
Results: We find that the global, transverse kink mode is efficiently excited for a range of attack angles and qualitatively in agreement with theoretical expectations. The period and damping time are found to be independent of the attack angle. For larger values of the attack angle, the global (longitudinal) slow wave is excited, whereas for intermediate values the second harmonic kink mode is also present. Title: Nonlinear fast magnetoacoustic wave propagation in the neighbourhood of a 2D magnetic X-point: oscillatory reconnection Authors: McLaughlin, J. A.; De Moortel, I.; Hood, A. W.; Brady, C. S. Bibcode: 2009A&A...493..227M Altcode: 2009arXiv0901.1781M Context: This paper extends the models of Craig & McClymont (1991, ApJ, 371, L41) and McLaughlin & Hood (2004, A&A, 420, 1129) to include finite β and nonlinear effects.
Aims: We investigate the nature of nonlinear fast magnetoacoustic waves about a 2D magnetic X-point.
Methods: We solve the compressible and resistive MHD equations using a Lagrangian remap, shock capturing code (Arber et al. 2001, J. Comp. Phys., 171, 151) and consider an initial condition in {v}×{B} \cdot {hat{z}} (a natural variable of the system).
Results: We observe the formation of both fast and slow oblique magnetic shocks. The nonlinear wave deforms the X-point into a “cusp-like” point which in turn collapses to a current sheet. The system then evolves through a series of horizontal and vertical current sheets, with associated changes in connectivity, i.e. the system exhibits oscillatory reconnection. Our final state is non-potential (but in force balance) due to asymmetric heating from the shocks. Larger amplitudes in our initial condition correspond to larger values of the final current density left in the system.
Conclusions: The inclusion of nonlinear terms introduces several new features to the system that were absent from the linear regime.

A movie is available in electronic form at http://www.aanda.org Title: Influence of a dense photosphere-like layer on vertical oscillations of a curved coronal slab Authors: Gruszecki, M.; Murawski, K.; McLaughlin, J. A. Bibcode: 2008A&A...489..413G Altcode: Aims: We consider a model of a two-dimensional curved solar coronal slab and explore the excitation and attenuation of fast magnetoacoustic vertical oscillations. We include a dense photosphere-like layer into the physical system.
Methods: The time-dependent, ideal magnetohydrodynamic equations are solved numerically to determine the spatial and temporal signatures of the impulsively excited oscillations.
Results: The numerical results reveal that the inclusion of the dense photosphere-like layer has a significant influence on the wave period (P) and attenuation time (τ ). The wave characteristics exhibit a stronger dependence on the mass density contrast between the loop and the photosphere than on the width of the transition layer, according to the parametric studies performed here. We find that P decreases and τ /P grows with the mass density contrast between the photosphere-like layer and solar corona, d_ph. At the limit of d_ph→ ∞ , P and τ /P attain their values which correspond to the case when the photosphere-like layer is removed from the system and its action is mimicked by implementation of line-tying boundary conditions at the bottom boundary.
Conclusions: The inclusion of a dense photosphere-like layer results in more efficient excitation and attenuation of vertical waves oscillation, compared with the case of line-tying boundary conditions. The enhancement of the attenuation rate arises from energy leakage through the photosphere-like layer. Title: 3D MHD Coronal Oscillations about a Magnetic Null Point: Application of WKB Theory Authors: McLaughlin, J. A.; Ferguson, J. S. L.; Hood, A. W. Bibcode: 2008SoPh..251..563M Altcode: 2007arXiv0712.1731M; 2008SoPh..tmp....8M This paper is a demonstration of how the WKB approximation can be used to help solve the linearised 3D MHD equations. Using Charpit's method and a Runge - Kutta numerical scheme, we have demonstrated this technique for a potential 3D magnetic null point, B=[x,εy,−(ε+1)z]. Under our cold-plasma assumption, we have considered two types of wave propagation: fast magnetoacoustic and Alfvén waves. We find that the fast magnetoacoustic wave experiences refraction towards the magnetic null point and that the effect of this refraction depends upon the Alfvén speed profile. The wave and thus the wave energy accumulate at the null point. We have found that current buildup is exponential and the exponent is dependent upon ε. Thus, for the fast wave there is preferential heating at the null point. For the Alfvén wave, we find that the wave propagates along the field lines. For an Alfvén wave generated along the fan plane, the wave accumulates along the spine. For an Alfvén wave generated across the spine, the value of ε determines where the wave accumulation will occur: fan plane (ε=1), along the x-axis (0<ε<1) or along the y-axis (ε>1). We have shown analytically that currents build up exponentially, leading to preferential heating in these areas. The work described here highlights the importance of understanding the magnetic topology of the coronal magnetic field for the location of wave heating. Title: Three-dimensional Magnetohydrodynamic Wave Behavior in Active Regions: Individual Loop Density Structure Authors: McLaughlin, J. A.; Ofman, L. Bibcode: 2008ApJ...682.1338M Altcode: We present the numerical results from a three-dimensional (3D) nonlinear MHD simulation of wave activity in an idealized active region in which individual, realistic loop density structure is included. The active region is modeled by an initially force-free, dipole magnetic configuration with gravitationally stratified density and contains a loop with a higher density than its surroundings. This study represents an extension to the model of Ofman & Thompson. As found in their work, we see that fast wave propagation is distorted by the Alfvén speed profile and that the wave propagation generates field line oscillations, which are rapidly damped. We find that the addition of a high-density loop significantly changes the behavior inside that loop, specifically in that the loop can support trapped waves. We also find that the impact of the fast wave impulsively excites both horizontal and vertical loop oscillations. From a parametric study of the oscillations, we find that the amplitude of the oscillations decreases with increasing density contrast, whereas the period and damping time increase. This is one of the key results presented here: that individual loop density structure can influence the damping rate, and specifically that the damping time increases with increasing density contrast. All these results were compared with an additional study performed on a straight coronal loop with similar parameters. Through comparison with the straight loop, we find that the damping mechanism in our curved loop is wave leakage due to curvature. The work performed here highlights the importance of including individual loop density structure in the modeling of active regions and illustrates the need for obtaining accurate density measurements for coronal seismology. Title: 3d Simulations Of Excitation And Damping Of Waves In A Dipole Active Region Authors: Selwa, Malgorzata; Ofman, L.; McLaughlin, J. Bibcode: 2007AAS...210.9114S Altcode: 2007BAAS...39R.206S We present numerical results of three dimensional MHD model of an idealized active region field. The active region is initialized as a force-free dipole magnetic configuration with gravitationally stratified density and contains a loop with a higher density than its surroundings. This study represents an extension to the model of McLaughlin & Ofman (2007). We examine the impact of a different density profiles of the loop on excitation and damping of kink waves by introducing a velocity or pressure pulse which models the impact of a flare on surrounding fields. We study the resulting loop oscillations and compare our results with TRACE observations. Title: 3D MHD Model of Waves in an Active Region Authors: Ofman, L.; McLaughlin, J. Bibcode: 2006AGUFMSH33B0416O Altcode: Wave activity associated with flares and CME's have been observed with SOHO, TRACE, and other satellites. The propagation and dissipation of the waves provide information on the coronal magnetic structures. In particular, MHD waves were observed in coronal active region AR8270 following a flare with TRACE on July 14, 1998. In this study, three dimensional MHD model of the active region field was constructed using National Solar Observatory (NSO) Kitt Peak magnetogram and potential extrapolation of the magnetic field, together with gravitationally stratified density as the initial state. The model was evolved to steady state, and a velocity pulse with amplitude of ~100 km/sec was launched into the active region from below to mimic the observed effect of the flare. It was found that the global oscillations in the model active region are in good qualitative agreement with observations. The main difference between the observations and the model is in the oscillation of several individual loops that damp on longer time scale, compared to the corresponding magnetic field line oscillation damping in the model. We investigate the effects of global active region magnetic structure, as well as local loop structure on the trapping and damping of waves in the active region. Title: 3D MHD Wave Behavior in Active Regions: Trapped Modes Authors: McLaughlin, J. A.; Ofman, L. Bibcode: 2006AGUFMSH33B0413M Altcode: We present the numerical results of a fast magnetoacoustic wave propagating within an idealized active region. The active region is modeled by an initially force-free, dipole magnetic configuration with gravitationally stratified density and contains a loop with a higher density than its surroundings. This study represents an extension to the model of Ofman &Thompson (2002). As found in their work, we see that fast wave propagation is distorted by the Alfvén speed profile and that the wave propagation generates fieldline oscillations and these oscillations are rapidly damped. Inside the high density loop, we find that the amplitude of these oscillations decreases as the density contrast, ξ, increases. We also find that the high density loop undergoes both vertical and horizontal oscillations. We calculate how the rate of wave damping in our loop varies with ξ and find a local minimum at about ξ=2.5, and we argue that this is evidence of wave trapping. Thus, this work illustrates the importance of obtaining accurate loop density measurements for coronal seismology. Title: MHD mode coupling in the neighbourhood of a 2D null point Authors: McLaughlin, J. A.; Hood, A. W. Bibcode: 2006A&A...459..641M Altcode: 2007arXiv0712.2402M Context: .At this time there does not exist a robust set of rules connecting low and high β waves across the β ≈ 1 layer. The work here contributes specifically to what happens when a low β fast wave crosses the β ≈ 1 layer and transforms into high β fast and slow waves.
Aims: .The nature of fast and slow magnetoacoustic waves is investigated in a finite β plasma in the neighbourhood of a two-dimensional null point.
Methods: .The linearised equations are solved in both polar and cartesian forms with a two-step Lax-Wendroff numerical scheme. Analytical work (e.g. small β expansion and WKB approximation) also complement the work.
Results: .It is found that when a finite gas pressure is included in magnetic equilibrium containing an X-type null point, a fast wave is attracted towards the null by a refraction effect and that a slow wave is generated as the wave crosses the β ≈ 1 layer. Current accumulation occurs close to the null and along nearby separatrices. The fast wave can now pass through the origin due to the non-zero sound speed, an effect not previously seen in related papers but clear seen for larger values of β. Some of the energy can now leave the region of the null point and there is again generation of a slow wave component (we find that the fraction of the incident wave converted to a slow wave is proportional to β). We conclude that there are two competing phenomena; the refraction effect (due to the variable Alfvén speed) and the contribution from the non-zero sound speed.
Conclusions: .These experiments illustrate the importance of the magnetic topology and of the location of the β ≈ 1 layer in the system. Title: Three-Dimensional MHD Models of Waves in Active Regions: Application to Coronal Seismology Authors: McLaughlin, J. A.; Ofman, L. Bibcode: 2006ESASP.617E.102M Altcode: 2006soho...17E.102M We present results from three-dimensional MHD simulations of the behaviour of MHD waves in 3D models of coronal active regions and loops. The models of the active regions are constructed by using a dipole magnetic field and gravitationally stratified coronal density structure. We compare the main features of the model with those seen recently by the SOHO and TRACE satellites and investigate the application of the results to coronal seismology. We discuss the possible applications of STEREO data to the improvement of our model. Title: Waves In Active Regions: Comparing Observations And 3D MHD Models Authors: Ofman, Leon; McLaughlin, J. Bibcode: 2006SPD....37.1802O Altcode: 2006BAAS...38..246O Recent TRACE observations of active regions in EUV shows waveactivity in coronal active regions following impulsive events.Motivated by these observations we construct 3D MHD models of theactive regions using photospheric magnetic field as boundarycondition from SOHO MDI or Kitt Peak data, and nonuniform densitystructure to model individual loops. We introduce several forms ofvelocity and density pulses to model the effects of impulsiveevents, such as flares, and follow the evolution of the modelactive region. We find good agreement between the observedevolution of active regions, and the 3D MHD models. Thus, wedemonstrate that the 3D MHD models can be used for coronalseismology. In the near future STEREO data may provide improvedinput for these models. Title: Magnetohydrodynamics wave propagation in the neighbourhood of two dipoles Authors: McLaughlin, J. A.; Hood, A. W. Bibcode: 2006A&A...452..603M Altcode: 2007arXiv0712.1784M Context: .This paper is the third in a series of investigations by the authors.
Aims: .The nature of fast magnetoacoustic and Alfvén waves is investigated in a 2D β=0 plasma in the neighbourhood of two dipoles.
Methods: .We use both numerical simulations (two-step Lax-Wendroff scheme) and analytical techniques (WKB approximation).
Results: .It is found that the propagation of the linear fast wave is dictated by the Alfvén speed profile and that close to the null, the wave is attracted to the neutral point. However, it is also found that in this magnetic configuration some of the wave can escape the refraction effect; this had not been seen in previous investigations by the authors. The wave split occurs near the regions of very high Alfvén speed (found near the loci of the two dipoles). Also, for the set-up investigated it was found that 40% of the wave energy accumulates at the null. Ohmic dissipation will then extract the wave energy at this point. The Alfvén wave behaves in a different manner in that part of the wave accumulates along the separatrices and part escapes. Hence, the current density will accumulate at this part of the topology and this is where wave heating will occur.
Conclusions: .The phenomenon of wave accumulation at a specific place is a feature of both wave types, as is the result that a fraction of the wave can now escape the numerical box when propagating in this magnetic configuration. Title: 3d Mhd Wave Behavior In Active Regions: Modeling Techniques Authors: McLaughlin, James A.; Ofman, L. Bibcode: 2006SPD....37.0116M Altcode: 2006BAAS...38..218M We have performed simulations of three-dimensional MHD wave propagation in models of coronal active regions. Here, we present descriptions of the methodology and techniques that are used in the construction of such simulations. These include:1) The MHD equations solved and the velocity perturbations used to simulate, for example, incoming EIT waves.2) The construction of the active region model using extrapolations of the observed photospheric magnetic field and gravitational stratification of the coronal density structure.3) The inclusion of the density structure of individual, realistic coronal loops using a new technique.We also discuss the application of the model to coronal seismology and the possibility of using STEREO data to the improvement of the simulations. Title: 3D MHD models of waves in active regions: application to coronal seismology Authors: McLaughlin, J. A.; Ofman, L. Bibcode: 2006AGUSMSH52A..06M Altcode: We present results from three-dimensional MHD simulations of the behavior of MHD waves in realistic models of coronal active regions. The models of the active regions are constructed by using the observed photospheric magnetic field and gravitationally stratified coronal density structure with individual loops. We compare the main features of the model with those seen recently by the SOHO and TRACE satellites, and investigate the application of the results to coronal seismology. We discuss the possible application of STEREO data to the improvement of our model. Title: MHD wave propagation in the neighbourhood of two null points Authors: McLaughlin, J. A.; Hood, A. W. Bibcode: 2005A&A...435..313M Altcode: 2007arXiv0712.1809M The nature of fast magnetoacoustic and Alfvén waves is investigated in a zero β plasma in the neighbourhood of a pair of two-dimensional null points. This gives an indication of wave propagation in the low β solar corona, for a more complicated magnetic configuration than that looked at by McLaughlin & Hood (2004, A&A, 420, 1129). It is found that the fast wave is attracted to the null points and that the front of the wave slows down as it approaches the null point pair. Here, the wave splits and part of the wave accumulates at one null and the rest at the other. Current density will then accumulate at these points and ohmic dissipation will then extract the energy in the wave at these points. This suggests locations where wave heating will occur in the corona. The Alfvén wave behaves in a different manner in that the wave accumulates along the separatrices. Hence, the current density will accumulate at this part of the topology and this is where wave heating will occur. However, the phenomenon of wave accumulation at a specific place is a feature of both wave types, and illustrates the importance of studying the topology of the corona when considering MHD wave propagation. Title: GRB 050525a: SARA observations. Authors: Homewood, A.; Hartmann, D. H.; Garimella, K.; Henson, G.; McLaughlin, J.; Brimeyer, A. Bibcode: 2005GCN..3491....1H Altcode: No abstract at ADS Title: Preferential Heating in the Neighbourhood of a Two-Dimensional Null Point Authors: McLaughlin, J. A.; Hood, A. W. Bibcode: 2004ESASP.575...74M Altcode: 2004soho...15...74M No abstract at ADS Title: MHD wave propagation in the neighbourhood of a two-dimensional null point Authors: McLaughlin, J. A.; Hood, A. W. Bibcode: 2004A&A...420.1129M Altcode: 2007arXiv0712.1792M The nature of fast magnetoacoustic and Alfvén waves is investigated in a zero β plasma. This gives an indication of wave propagation in the low β solar corona. It is found that for a two-dimensional null point, the fast wave is attracted to that point and the front of the wave slows down as it approaches the null point, causing the current density to accumulate there and rise rapidly. Ohmic dissipation will extract the energy in the wave at this point. This illustrates that null points play an important role in the rapid dissipation of fast magnetoacoustic waves and suggests the location where wave heating will occur in the corona. The Alfvén wave behaves in a different manner in that the wave energy is dissipated along the separatrices. For Alfvén waves that are decoupled from fast waves, the value of the plasma β is unimportant. However, the phenomenon of dissipating the majority of the wave energy at a specific place is a feature of both wave types. Title: MHD Waves in the Neighbourhood of a 2D X-Type Neutral Point Authors: McLaughlin, J. A.; Hood, A. W. Bibcode: 2004ESASP.547..537M Altcode: 2004soho...13..537M A linear, fast magnetoacoustic wave is generated at a boundary and travels towards an magnetic X-type neutral point. Due to refraction, the wave wraps itself around the null point, causing a large current to accumulate there. Simulations show that the current build up is exponential in time. The numerical simulations are in good agreement with analytic work based on a WKB solution obtained by the method of characteristics. Title: The Use of Zylon Fibers in ULDB Balloons Authors: Zimmerman, M.; Seely, L.; McLaughlin, J. Bibcode: 2002cosp...34E2817Z Altcode: 2002cosp.meetE2817Z Early in the development of the ULDB balloon, Zylon (PBO) was selected as the tendon material due to its favorable stress-strain properties. It is a next generation super fiber whose strength and modulus are almost double those of the p-Aramid fibers. In addition there are two versions of the Zylon, As Spun (AS) and High Modulus (HM). Data will be presented on why the HM was chosen. Early in the development process, it was learned that this material exhibited an unusual sensitivity to degradation by ambient light. This is in addition to the expected sensitivity to UV radiation (Ultraviolet). The fiber manufacturer reported all of these properties in their literature. Due to the operating environment of the ULDB (Ultra Long Duration Balloon) it is necessary to protect the tendons from both visible and UV radiation. Methods to protect the tendons will be discussed. In addition, information on the long term exposure of the braided tendon over a thirty-six month period in a controlled manufacturing plant will be provided. Title: Periodic Comet Swift-Tuttle (1992t) Authors: Jones, B.; Pina, R. K.; Milone, E. F.; Sarmecanic, J. R.; Puetter, R. C.; McLaughlin, J.; Gehrz, R. D.; Lawrence, G.; Flugaur, K.; Woodward, C. E. Bibcode: 1992IAUC.5654....2J Altcode: B. Jones and R. K. Pina, University of California at San Diego; and E. F. Milone, Rothney Astrophysical Observatory, University of Calgary, report that 11.7-micron images (0".83/pixel) of P/Swift- Tuttle were obtained on Nov. 7.1 and 8.1 UT by Pina, J. R. Sarmecanic, and Milone (field-of-view of 30" x 17") and on Nov. 12.1 and 13.1 by R. C. Puetter and J. McLaughlin (19" x 24"), using the UCSD 10-micron array camera at the Mt. Lemmon Infrared Observatory. The comet showed a decrease in flux of 28 percent between the two dates, going from 37.7 to 27.3 Jy in a 5".8 beam centered on the nucleus. R. D. Gehrz, G. Lawrence, and K. Flugaur, University of Minnesota; and C. E. Woodward, University of Wyoming, report thermal infrared measurements of P/Swift-Tuttle on Nov. 12.0 UT using a multifilter GaGe bolometer with a 9" diaphragm on the 0.76-m telescope of O'Brien Observatory. The chopper throw placed the reference beams 45" north and south of the coma center. The infrared broadband magnitudes are K [6.53 (3-sigma upper limit), L = 5.9 +/- 0.3, M = 3.0 +/- 0.3, N (7-14 microns) = -0.2 +/- 0.1, Q (18-22 microns) [-2.0 (3-sigma upper limit). Additional photometry through the narrow-band IRTF silicate filter set gave magnitudes of [7.8 microns] = 0.7 +/- 0.3, [8.7 microns] = -0.3 +/- 0.1, [9.8 microns] = -0.7 +/- 0.15, [10.3 microns] = -0.64 +/- 0.3, [11.6 microns] = -1.4 +/- 0.3, and [12.5 microns] = -1.1 +/- 0.1. The data are consistent with continuum emission from a 367-K blackbody. There is no evidence for a strong 10-micron silicate emission feature. Title: An example of the Vilkovisky-de Witt effective action in one-loop quantum gravity. Authors: Allen, B.; McLaughlin, J.; Ottewill, A. C. Bibcode: 1992mgm..conf..545A Altcode: No abstract at ADS Title: Renormalised Energy Density on the Horizon of a Kerr Black Hole Authors: Jensen, B.; McLaughlin, J.; Ottewill, A. Bibcode: 1989grg..conf..697J Altcode: No abstract at ADS