Millimeter light curves of Sagittarius A* observed during the 2017 Event Horizon Telescope campaign
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Date
2022-05-01
Authors
Wielgus, Maciek
Marchili, Nicola
Martí-Vidal, Iván
Keating, Garrett K.
Ramakrishnan, Venkatessh
Tiede, Paul
Fomalont, Ed
Issaoun, Sara
Neilsen, Joey
Nowak, Michael A.
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OA Version
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M. Wielgus, N. Marchili, I. Martí-Vidal, G.K. Keating, V. Ramakrishnan, P. Tiede, E. Fomalont, S. Issaoun, J. Neilsen, M.A. Nowak, L. Blackburn, C.F. Gammie, C. Goddi, D. Haggard, D. Lee, M. Moscibrodzka, A.J. Tetarenko, G.C. Bower, C.-K. Chan, K. Chatterjee, P.M. Chesler, J. Dexter, S.S. Doeleman, B. Georgiev, M. Gurwell, M.D. Johnson, D.P. Marrone, A. Mus, D. Psaltis, B. Ripperda, G. Witzel, K. Akiyama, A. Alberdi, W. Alef, J. Carlos Algaba, R. Anantua, K. Asada, R. Azulay, U. Bach, A.-K. Baczko, D. Ball, M. Baloković, J. Barrett, M. Bauböck, B.A. Benson, D. Bintley, R. Blundell, W. Boland, K.L. Bouman, H. Boyce, M. Bremer, C.D. Brinkerink, R. Brissenden, S. Britzen, A.E. Broderick, D. Broguiere, T. Bronzwaer, S. Bustamante, D.-Y. Byun, J.E. Carlstrom, C. Ceccobello, A. Chael, S. Chatterjee, M.-T. Chen, Y. Chen, I. Cho, P. Christian, N.S. Conroy, J.E. Conway, J.M. Cordes, T.M. Crawford, G.B. Crew, A. Cruz-Osorio, Y. Cui, J. Davelaar, M. De Laurentis, R. Deane, J. Dempsey, G. Desvignes, V. Dhruv, S.A. Dzib, R.P. Eatough, R. Emami, H. Falcke, J. Farah, V.L. Fish, H. Alyson Ford, R. Fraga-Encinas, W.T. Freeman, P. Friberg, C.M. Fromm, A. Fuentes, P. Galison, R. García, O. Gentaz, R. Gold, A.I. Gómez-Ruiz, J.L. Gómez, M. Gu, K. Hada, K. Haworth, M.H. Hecht, R. Hesper, L.C. Ho, P. Ho, M. Honma, C.-W.L. Huang, L. Huang, D.H. Hughes, S. Ikeda, C.M. Violette Impellizzeri, M. Inoue, D.J. James, B.T. Jannuzi, M. Janssen, B. Jeter, W. Jiang, A. Jiménez-Rosales, S. Jorstad, A.V. Joshi, T. Jung, M. Karami, R. Karuppusamy, T. Kawashima, M. Kettenis, D.-J. Kim, J.-Y. Kim, J. Kim, J. Kim, M. Kino, J. Yi Koay, P. Kocherlakota, Y. Kofuji, P.M. Koch, S. Koyama, C. Kramer, M. Kramer, T.P. Krichbaum, C.-Y. Kuo, N. La Bella, T.R. Lauer, S.-S. Lee, P. Kin Leung, A. Levis, Z. Li, R. Lico, G. Lindahl, M. Lindqvist, M. Lisakov, J. Liu, K. Liu, E. Liuzzo, W.-P. Lo, A.P. Lobanov, L. Loinard, C. Lonsdale, R.-S. Lu, J. Mao, S. Markoff, A.P. Marscher, S. Matsushita, L.D. Matthews, L. Medeiros, K.M. Menten, D. Michalik, I. Mizuno, Y. Mizuno, J.M. Moran, K. Moriyama, C. Müller, G. Musoke, I. Myserlis, A. Nadolski, H. Nagai, N.M. Nagar, M. Nakamura, R. Narayan, G. Narayanan, I. Natarajan, A. Nathanail, S. Navarro Fuentes, R. Neri, C. Ni, A. Noutsos, J. Oh, H. Okino, H. Olivares, G.N. Ortiz-León, T. Oyama, F. Özel, D.C.M. Palumbo, G. Filippos Paraschos, J. Park, H. Parsons, N. Patel, U.-L. Pen, D.W. Pesce, V. Piétu, R. Plambeck, A. PopStefanija, O. Porth, F.M. Pötzl, B. Prather, J.A. Preciado-López, H.-Y. Pu, R. Rao, M.G. Rawlings, A.W. Raymond, L. Rezzolla, A. Ricarte, F. Roelofs, A. Rogers, E. Ros, C. Romero-Canizales, A. Roshanineshat, H. Rottmann, A.L. Roy, I. Ruiz, C. Ruszczyk, K.L.J. Rygl, S. Sánchez, D. Sánchez-Argüelles, M. Sánchez-Portal, M. Sasada, K. Satapathy, T. Savolainen, F. Peter Schloerb, K.-F. Schuster, L. Shao, Z. Shen, D. Small, B. Won Sohn, J. SooHoo, K. Souccar, H. Sun, F. Tazaki, R.P.J. Tilanus, M. Titus, P. Torne, E. Traianou, T. Trent, S. Trippe, I. van Bemmel, H. Jan van Langevelde, D.R. van Rossum, J. Vos, J. Wagner, D. Ward-Thompson, J. Wardle, J. Weintroub, N. Wex, R. Wharton, K. Wiik, M.F. Wondrak, G.N. Wong, Q. Wu, P. Yamaguchi, D. Yoon, A. Young, K. Young, Z. Younsi, F. Yuan, Y.-F. Yuan, J. Anton Zensus, S. Zhang, G.-Y. Zhao, S.-S. Zhao. 2022. "Millimeter Light Curves of Sagittarius A* Observed during the 2017 Event Horizon Telescope Campaign" Letters of the Astrophysical Journal, Volume 930, Issue 2, pp.L19-L19. https://doi.org/10.3847/2041-8213/ac6428
Abstract
The Event Horizon Telescope (EHT) observed the compact radio source, Sagittarius A* (Sgr A*), in the Galactic Center on 2017 April 5–11 in the 1.3 mm wavelength band. At the same time, interferometric array data from the Atacama Large Millimeter/submillimeter Array and the Submillimeter Array were collected, providing Sgr A* light curves simultaneous with the EHT observations. These data sets, complementing the EHT very long baseline interferometry, are characterized by a cadence and signal-to-noise ratio previously unattainable for Sgr A* at millimeter wavelengths, and they allow for the investigation of source variability on timescales as short as a minute. While most of the light curves correspond to a low variability state of Sgr A*, the April 11 observations follow an X-ray flare and exhibit strongly enhanced variability. All of the light curves are consistent with a red-noise process, with a power spectral density (PSD) slope measured to be between −2 and −3 on timescales between 1 minute and several hours. Our results indicate a steepening of the PSD slope for timescales shorter than 0.3 hr. The spectral energy distribution is flat at 220 GHz, and there are no time lags between the 213 and 229 GHz frequency bands, suggesting low optical depth for the event horizon scale source. We characterize Sgr A*’s variability, highlighting the different behavior observed just after the X-ray flare, and use Gaussian process modeling to extract a decorrelation timescale and a PSD slope. We also investigate the systematic calibration uncertainties by analyzing data from independent data reduction pipelines.
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© 2022. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.