Millimeter Light Curves of Sagittarius A* Observed during the 2017 Event Horizon Telescope Campaign

Maciek Wielgus*, Nicola Marchili, Iván Martí-Vidal, Garrett K. Keating, Venkatessh Ramakrishnan, Paul Tiede, Ed Fomalont, Sara Issaoun, Joey Neilsen, Michael A. Nowak, Lindy Blackburn, Charles F. Gammie, Ciriaco Goddi, Daryl Haggard, Daeyoung Lee, Monika Moscibrodzka, Alexandra J. Tetarenko, Geoffrey C. Bower, Chi Kwan Chan, Koushik ChatterjeePaul M. Chesler, Jason Dexter, Sheperd S. Doeleman, Boris Georgiev, Mark Gurwell, Michael D. Johnson, Daniel P. Marrone, Alejandro Mus, Dimitrios Psaltis, Bart Ripperda, Gunther Witzel, Kazunori Akiyama, Antxon Alberdi, Walter Alef, Juan Carlos Algaba, Richard Anantua, Keiichi Asada, Rebecca Azulay, Uwe Bach, Anne Kathrin Baczko, David Ball, Mislav Baloković, John Barrett, Michi Bauböck, Bradford A. Benson, Dan Bintley, Raymond Blundell, Wilfred Boland, Katherine L. Bouman, Hope Boyce, Michael Bremer, Christiaan D. Brinkerink, Roger Brissenden, Silke Britzen, Avery E. Broderick, Dominique Broguiere, Thomas Bronzwaer, Sandra Bustamante, Do Young Byun, John E. Carlstrom, Chiara Ceccobello, Andrew Chael, Shami Chatterjee, Ming Tang Chen, Yongjun Chen, Ilje Cho, Pierre Christian, Nicholas S. Conroy, John E. Conway, James M. Cordes, Thomas M. Crawford, Geoffrey B. Crew, Alejandro Cruz-Osorio, Yuzhu Cui, Jordy Davelaar, Mariafelicia De Laurentis, Roger Deane, Jessica Dempsey, Gregory Desvignes, Vedant Dhruv, Sergio A. Dzib, Ralph P. Eatough, Razieh Emami, Heino Falcke, Joseph Farah, Vincent L. Fish, H. Alyson Ford, Raquel Fraga-Encinas, William T. Freeman, Per Friberg, Christian M. Fromm, Antonio Fuentes, Peter Galison, Roberto García, Olivier Gentaz, Roman Gold, Arturo I. Gómez-Ruiz, José L. Gómez, Minfeng Gu, Kazuhiro Hada, Kari Haworth, Michael H. Hecht, Ronald Hesper, Luis C. Ho, Paul Ho, Mareki Honma, Chih Wei L. Huang, Lei Huang, David H. Hughes, Shiro Ikeda, C. M.Violette Impellizzeri, Makoto Inoue, David J. James, Buell T. Jannuzi, Michael Janssen, Britton Jeter, Wu Jiang, Alejandra Jiménez-Rosales, Svetlana Jorstad, Abhishek V. Joshi, Taehyun Jung, Mansour Karami, Ramesh Karuppusamy, Tomohisa Kawashima, Mark Kettenis, Dong Jin Kim, Jae Young Kim, Jongsoo Kim, Junhan Kim, Motoki Kino, Jun Yi Koay, Prashant Kocherlakota, Yutaro Kofuji, Patrick M. Koch, Shoko Koyama, Carsten Kramer, Michael Kramer, Thomas P. Krichbaum, Cheng Yu Kuo, Noemi La Bella, Tod R. Lauer, Sang Sung Lee, Po Kin Leung, Aviad Levis, Zhiyuan Li, Rocco Lico, Greg Lindahl, Michael Lindqvist, Mikhail Lisakov, Jun Liu, Kuo Liu, Elisabetta Liuzzo, Wen Ping Lo, Andrei P. Lobanov, Laurent Loinard, Colin Lonsdale, Ru Sen Lu, Jirong Mao, Sera Markoff, Alan P. Marscher, Satoki Matsushita, Lynn D. Matthews, Lia Medeiros, Karl M. Menten, Daniel Michalik, Izumi Mizuno, Yosuke Mizuno, James M. Moran, Kotaro Moriyama, Cornelia Müller, Gibwa Musoke, Ioannis Myserlis, Andrew Nadolski, Hiroshi Nagai, Neil M. Nagar, Masanori Nakamura, Ramesh Narayan, Gopal Narayanan, Iniyan Natarajan, Antonios Nathanail, Santiago Navarro Fuentes, Roberto Neri, Chunchong Ni, Aristeidis Noutsos, Junghwan Oh, Hiroki Okino, Héctor Olivares, Gisela N. Ortiz-León, Tomoaki Oyama, Feryal Özel, Daniel C.M. Palumbo, Georgios Filippos Paraschos, Jongho Park, Harriet Parsons, Nimesh Patel, Ue Li Pen, Dominic W. Pesce, Vincent Piétu, Richard Plambeck, Aleksandar PopStefanija, Oliver Porth, Felix M. Pötzl, Ben Prather, Jorge A. Preciado-López, Hung Yi Pu, Ramprasad Rao, Mark G. Rawlings, Alexander W. Raymond, Luciano Rezzolla, Angelo Ricarte, Freek Roelofs, Alan Rogers, Eduardo Ros, Cristina Romero-Canizales, Arash Roshanineshat, Helge Rottmann, Alan L. Roy, Ignacio Ruiz, Chet Ruszczyk, Kazi L.J. Rygl, Salvador Sánchez, David Sánchez-Argüelles, Miguel Sánchez-Portal, Mahito Sasada, Kaushik Satapathy, Tuomas Savolainen, F. Peter Schloerb, Karl Friedrich Schuster, Lijing Shao, Zhiqiang Shen, Des Small, Bong Won Sohn, Jason SooHoo, Kamal Souccar, He Sun, Fumie Tazaki, Remo P.J. Tilanus, Michael Titus, Pablo Torne, Efthalia Traianou, Tyler Trent, Sascha Trippe, Ilse van Bemmel, Huib Jan van Langevelde, Daniel R. van Rossum, Jesse Vos, Jan Wagner, Derek Ward-Thompson, John Wardle, Jonathan Weintroub, Norbert Wex, Robert Wharton, Kaj Wiik, Michael F. Wondrak, George N. Wong, Qingwen Wu, Paul Yamaguchi, Doosoo Yoon, André Young, Feng Yuan, Ken Young, Ziri Younsi, Ye Fei Yuan, J. Anton Zensus, Shuo Zhang, Guang Yao Zhao, Shan Shan Zhao

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

66 Citations (Scopus)

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.

Original languageEnglish
Article numberL19
JournalAstrophysical Journal Letters
Volume930
Issue number2
DOIs
Publication statusPublished - 2022 May 1

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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