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First M87 Event Horizon Telescope Results. III. Data Processing and Calibration

2019; IOP Publishing; Volume: 875; Issue: 1 Linguagem: Inglês

10.3847/2041-8213/ab0c57

2041-8213

Kazunori Akiyama, A. Alberdi, W. Alef, Keiichi Asada, Rebecca Azulay, Anne-Kathrin Baczko, David Ball, M. Baloković, John Barrett, Dan Bintley, Lindy Blackburn, W. Boland, Katherine L. Bouman, Geoffrey C. Bower, Michael Bremer, Christiaan D. Brinkerink, Roger Brissenden, S. Britzen, Avery E. Broderick, Dominique Broguière, Thomas Bronzwaer, Do‐Young Byun, J. E. Carlstrom, Andrew Chael, Chi‐kwan Chan, Shami Chatterjee, Koushik Chatterjee, Ming‐Tang Chen, Xiaopeng Cheng, Ilje Cho, Pierre Christian, J. E. Conway, J. M. Cordes, G. Crew, Yuzhu Cui, Jordy Davelaar, Mariafelicia De Laurentis, Roger Deane, Jessica Dempsey, G. Desvignes, Jason Dexter, Sheperd S. Doeleman, Ralph P. Eatough, H. Falcke, Vincent L. Fish, Ed Fomalont, Raquel Fraga-Encinas, Per Friberg, Christian M. Fromm, José L. Gómez, Peter Galison, Charles F. Gammie, Roberto García, Olivier Gentaz, Boris Georgiev, C. Goddi, Roman Gold, Minfeng Gu, Mark Gurwell, Kazuhiro Hada, M. H. Hecht, R. Hesper, Luis C. Ho, Paul T. P. Ho, Mareki Honma, Chih-Wei L. Huang, Lei 磊 Huang 黄, D. H. Hughes, Shiro Ikeda, Makoto Inoue, Sara Issaoun, D. J. James, Buell T. Jannuzi, Michaël Janssen, Britton Jeter, Chih-Wei L. Huang, Michael D. Johnson, Svetlana G. Jorstad, Taehyun Jung, Mansour Karami, R. Karuppusamy, Tomohisa Kawashima, Garrett K. Keating, Mark Kettenis, Jae-Young Kim, Junhan Kim, Jongsoo Kim, Motoki Kino, Zhiyuan Li, Patrick M. Koch, Shoko Koyama, M. Krämer, C. Krämer, T. P. Krichbaum, Cheng‐Yu Kuo, Tod R. Lauer, Sang-Sung Lee, Yan-Rong Li, Zhiyuan Li, M. Lindqvist, Kuo Liu, Elisabetta Liuzzo, Wen-Ping Lo, A. P. Lobanov, Laurent Loinard, C. J. Lonsdale, Ru-Sen Lu, Nicholas R. MacDonald, Zhiyuan Li, Sera Markoff, Daniel P. Marrone, Alan P. Marscher, I. Martí‐Vidal, Satoki Matsushita, Lynn D. Matthews, Lia Medeiros, K. M. Menten, Yosuke Mizuno, Izumi Mizuno, J. M. Moran, Kotaro Moriyama, Monika Mościbrodzka, Cornelia Müller, Hiroshi Nagai, Neil M. Nagar, Masanori Nakamura, Ramesh Narayan, Gopal Narayanan, Iniyan Natarajan, R. Neri, Chunchong Ni, A. Noutsos, Hiroki Okino, Hèctor Olivares, Gisela N. Ortiz-León, Tomoaki Oyama, Feryal Özel, Daniel C. M. Palumbo, Nimesh Patel, Ue‐Li Pen, Dominic W. Pesce, Vincent Piétu, R. L. Plambeck, Aleksandar PopStefanija, Oliver Porth, Ben Prather, Jorge A. Preciado-López, Dimitrios Psaltis, Hung-Yi Pu, Venkatessh Ramakrishnan, Ramprasad Rao, Mark G. Rawlings, Alexander W. Raymond, Luciano Rezzolla, Bart Ripperda, Freek Roelofs, A. E. E. Rogers, E. Ros, Mel Rose, Arash Roshanineshat, Helge Rottmann, A. L. Roy, Chet Ruszczyk, Benjamin R. Ryan, K. L. J. Rygl, Salvador Sánchez, David Sánchez-Argüelles, Mahito Sasada, T. Savolainen, F. Peter Schloerb, K. Schüster, Lijing Shao, Zhi-Qiang Shen, Des Small, Bong Won Sohn, Jason Soohoo, Fumie Tazaki, Paul Tiede, R. P. J. Tilanus, Michael S. Titus, Kenji Toma, Pablo Torné, Tyler Trent, Sascha Trippe, Shuichiro Tsuda, Ilse van Bemmel, H. J. van Langevelde, Daniel R. van Rossum, Jan Wagner, J. F. C. Wardle, Jonathan Weintroub, Norbert Wex, Robert Wharton, Maciek Wielgus, George N. Wong, H. J. van Langevelde, André Young, Ken Young, Ziri Younsi, Jonathan Weintroub, Jonathan Weintroub, J. A. Zensus, Guang-Yao Zhao, Shan-Shan Zhao, Ziyan Zhu, R. J. Cappallo, Joseph Farah, Thomas W. Folkers, Zheng Meyer-Zhao, Daniel Michalik, Andrew Nadolski, Hiroaki Nishioka, Nicolas Pradel, Rurik A. Primiani, Kamal Souccar, Laura Vertatschitsch, Paul Yamaguchi,

Astrophysics and Cosmic Phenomena

We present the calibration and reduction of Event Horizon Telescope (EHT) 1.3mm radio wavelength observations of the supermassive black hole candidate at the center of the radio galaxy M87 and the quasar 3C 279, taken during the 2017 April 5-11 observing campaign. These global very long baseline interferometric observations include for the first time the highly sensitive Atacama Large Millimeter/submillimeter Array (ALMA); reaching an angular resolution of 25 micro-as, with characteristic sensitivity limits of ~1 mJy on baselines to ALMA and ~10 mJy on other baselines. The observations present challenges for existing data processing tools, arising from the rapid atmospheric phase fluctuations, wide recording bandwidth, and highly heterogeneous array. In response, we developed three independent pipelines for phase calibration and fringe detection, each tailored to the specific needs of the EHT. The final data products include calibrated total intensity amplitude and phase information. They are validated through a series of quality assurance tests that show consistency across pipelines and set limits on baseline systematic errors of 2% in amplitude and 1 degree in phase. The M87 data reveal the presence of two nulls in correlated flux density at ~3.4 and ~8.3 giga-lambda and temporal evolution in closure quantities, indicating intrinsic variability of compact structure on a timescale of days, or several light-crossing times for a few billion solar-mass black hole. These measurements provide the first opportunity to image horizon-scale structure in M87.