Broadband Multi-wavelength Properties of M87 during the 2017 Event Horizon Telescope Campaign

Abstract: In 2017, the Event Horizon Telescope (EHT) Collaboration succeeded in capturing the first direct image of the center of the M87 galaxy. The asymmetric ring morphology and size are consistent with theoretical expectations for a weakly accreting supermassive black hole of mass ∼6.5 × 109 M ⊙. The EHTC also partnered with several international facilities in space and on the ground, to arrange an extensive, quasi-simultaneous multi-wavelength campaign. This Letter presents the results and analysis of this campaign, as well as the multi-wavelength data as a legacy data repository. We captured M87 in a historically low state, and the core flux dominates over HST-1 at high energies, making it possible to combine core flux constraints with the more spatially precise very long baseline interferometry data. We present the most complete simultaneous multi-wavelength spectrum of the active nucleus to date, and discuss the complexity and caveats of combining data from different spatial scales into one broadband spectrum. We apply two heuristic, isotropic leptonic single-zone models to provide insight into the basic source properties, but conclude that a structured jet is necessary to explain M87’s spectrum. We can exclude that the simultaneous γ-ray emission is produced via inverse Compton emission in the same region producing the EHT mm-band emission, and further conclude that the γ-rays can only be produced in the inner jets (inward of HST-1) if there are strongly particle-dominated regions. Direct synchrotron emission from accelerated protons and secondaries cannot yet be excluded

Broadband multi-wavelength properties of M87 during the 2017 Event Horizon Telescope Campaign

Abstract In 2017, the Event Horizon Telescope (EHT) Collaboration succeeded in capturing the first direct image of the center of the M87 galaxy. The asymmetric ring morphology and size are consistent with theoretical expectations for a weakly accreting supermassive black hole of mass ∼6.5 × 10⁹ M☉. The EHTC also partnered with several international facilities in space and on the ground, to arrange an extensive, quasi-simultaneous multi-wavelength campaign. This Letter presents the results and analysis of this campaign, as well as the multi-wavelength data as a legacy data repository. We captured M87 in a historically low state, and the core flux dominates over HST-1 at high energies, making it possible to combine core flux constraints with the more spatially precise very long baseline interferometry data. We present the most complete simultaneous multi-wavelength spectrum of the active nucleus to date, and discuss the complexity and caveats of combining data from different spatial scales into one broadband spectrum. We apply two heuristic, isotropic leptonic single-zone models to provide insight into the basic source properties, but conclude that a structured jet is necessary to explain M87’s spectrum. We can exclude that the simultaneous γ-ray emission is produced via inverse Compton emission in the same region producing the EHT mm-band emission, and further conclude that the γ-rays can only be produced in the inner jets (inward of HST-1) if there are strongly particle-dominated regions. Direct synchrotron emission from accelerated protons and secondaries cannot yet be excluded.Collaborations The Event Horizon Telescope Collaboration236 Kazunori Akiyama21,39,40, Antxon Alberdi41, Walter Alef20, Richard Anantua18,40,42, Rebecca Azulay20,43,44, Anne-Kathrin Baczko20, David Ball45, John Barrett39, Dan Bintley46, Bradford A. Benson47,48, Lindy Blackburn18,40, Raymond Blundell18, Wilfred Boland49, Katherine L. Bouman18,40,50, Geoffrey C. Bower51, Hope Boyce13,14, Michael Bremer52, Christiaan D. Brinkerink11, Roger Brissenden18,40, Silke Britzen20, Avery E. Broderick53,54,55, Dominique Broguiere52, Thomas Bronzwaer11, Do-Young Byun19,56, John E. Carlstrom48,57,58,59, Andrew Chael60,237, Chi-kwan Chan45,61, Shami Chatterjee62, Koushik Chatterjee63, Ming-Tang Chen51, Yongjun Chen (陈永军)25,26, Paul M. Chesler40, Ilje Cho19,56, Pierre Christian64, John E. Conway65, James M. Cordes62, Thomas M. Crawford48,57, Geoffrey B. Crew39, Alejandro Cruz-Osorio66, Jordy Davelaar11,42,67, Mariafelicia De Laurentis66,68,69, Roger Deane70,71,72, Jessica Dempsey46, Gregory Desvignes73, Jason Dexter74, Sheperd S. Doeleman18,40, Ralph P. Eatough20,75, Heino Falcke11, Joseph Farah18,40,76, Vincent L. Fish39, Ed Fomalont77, H. Alyson Ford78, Raquel Fraga-Encinas11, Per Friberg46, Christian M. Fromm18,40,66, Antonio Fuentes41, Peter Galison40,79,80, Charles F. Gammie81,82, Roberto García52, Olivier Gentaz52, Boris Georgiev54,55, Roman Gold53,83, José L. Gómez41, Arturo I. Gómez-Ruiz84,85, Minfeng Gu (顾敏峰)25,86, Mark Gurwell18, Michael H. Hecht39, Ronald Hesper87, Luis C. Ho (何子山)88,89, Paul Ho3, Mareki Honma7,8,90, Chih-Wei L. Huang3, Lei Huang (黄磊)25,86, David H. Hughes84, Shiro Ikeda21,91,92,93, Makoto Inoue3, Sara Issaoun11, David J. James18,40, Buell T. Jannuzi45, Michael Janssen20, Britton Jeter54,55, Wu Jiang (江悟)25, Alejandra Jiménez-Rosales11, Michael D. Johnson18,40, Taehyun Jung19,56, Mansour Karami53,54, Ramesh Karuppusamy20, Mark Kettenis94, Dong-Jin Kim20, Jongsoo Kim19, Junhan Kim45,50, Jun Yi Koay3, Yutaro Kofuji8,90, Patrick M. Koch3, Shoko Koyama3, Michael Kramer20, Carsten Kramer52, Cheng-Yu Kuo3,95, Tod R. Lauer96, Aviad Levis50, Yan-Rong Li (李彦荣)97, Zhiyuan Li (李志远)98,99, Michael Lindqvist65, Rocco Lico41,20, Greg Lindahl18, Jun Liu (刘俊)20, Kuo Liu20, Elisabetta Liuzzo100, Wen-Ping Lo3,101, Andrei P. Lobanov20, Laurent Loinard102,103, Colin Lonsdale39, Nicholas R. MacDonald20, Jirong Mao (毛基荣)104,105,106, Nicola Marchili20,100, Daniel P. Marrone45, Alan P. Marscher15, Iván Martí-Vidal43,44, Satoki Matsushita3, Lynn D. Matthews39, Lia Medeiros45,107, Karl M. Menten20, Izumi Mizuno46, Yosuke Mizuno108,66, James M. Moran18,40, Kotaro Moriyama8,39, Monika Moscibrodzka11, Cornelia Müller11,20, Gibwa Musoke11,63, Alejandro Mus Mejías43,44, Hiroshi Nagai7,21, Neil M. Nagar34, Masanori Nakamura3,109, Ramesh Narayan18,40, Gopal Narayanan110, Iniyan Natarajan70,72,111, Antonios Nathanail66,112, Roberto Neri52, Chunchong Ni54,55, Aristeidis Noutsos20, Hiroki Okino8,90, Héctor Olivares11, Gisela N. Ortiz-León20, Tomoaki Oyama8, Feryal Özel45, Daniel C. M. Palumbo18,40, Nimesh Patel18, Ue-Li Pen53,113,114,115, Dominic W. Pesce18,40, Vincent Piétu52, Richard Plambeck116, Aleksandar PopStefanija110, Oliver Porth63,66, Felix M. Pötzl20, Ben Prather81, Jorge A. Preciado-López53, Dimitrios Psaltis45, Hung-Yi Pu3,53,117, Ramprasad Rao18, Mark G. Rawlings46, Alexander W. Raymond18,40, Luciano Rezzolla118,119,120, Angelo Ricarte18,40, Bart Ripperda42,121, Freek Roelofs11, Alan Rogers39, Eduardo Ros20, Mel Rose45, Arash Roshanineshat45, Helge Rottmann20, Alan L. Roy20, Chet Ruszczyk39, Kazi L. J. Rygl100, Salvador Sánchez122, David Sánchez-Arguelles84,85, Tuomas Savolainen20,123,124, F. Peter Schloerb110, Karl-Friedrich Schuster52, Lijing Shao20,89, Zhiqiang Shen (沈志强)25,26, Des Small94, Bong Won Sohn19,56,125, Jason SooHoo39, He Sun (孙赫)50, Fumie Tazaki8, Alexandra J. Tetarenko46, Paul Tiede54,55, Remo P. J. Tilanus11,12,45,126, Michael Titus39, Kenji Toma127,128, Pablo Torne20,122, Tyler Trent45, Efthalia Traianou20, Sascha Trippe31, Ilse van Bemmel94, Huib Jan van Langevelde94,129, Daniel R. van Rossum11, Jan Wagner20, Derek Ward-Thompson130, John Wardle131, Jonathan Weintroub18,40, Norbert Wex20, Robert Wharton20, Maciek Wielgus18,40, George N. Wong81, Qingwen Wu (吴庆文)132, Doosoo Yoon63, André Young11, Ken Young18, Ziri Younsi133,66,238, Feng Yuan (袁峰)25,86,134, Ye-Fei Yuan (袁业飞)135, J. Anton Zensus20, Guang-Yao Zhao41, Shan-Shan Zhao25 The Fermi Large Area Telescope Collaboration G. Principe10,32,33, M. Giroletti10, F. D’Ammando10, M. Orienti10 H.E.S.S. Collaboration H. Abdalla6, R. Adam136, F. Aharonian137,138,139, F. Ait Benkhali138, E. O. Angüner140, C. Arcaro6,*, C. Armand141, T. Armstrong142, H. Ashkar143, M. Backes6,144, V. Baghmanyan145, V. Barbosa Martins146, A. Barnacka147, M. Barnard6, Y. Becherini148, D. Berge146, K. Bernlöhr138, B. Bi149, M. Böttcher6, C. Boisson150, J. Bolmont151, M. de Bony de Lavergne141, M. Breuhaus138, F. Brun143, P. Brun143, M. Bryan152, M. Büchele153, T. Bulik154, T. Bylund148, S. Caroff151, A. Carosi141, S. Casanova145,138, T. Chand6, A. Chen155, G. Cotter142, M. Curyło154, J. Damascene Mbarubucyeye146, I. D. Davids144, J. Davies142, C. Deil138, J. Devin156, P. deWilt157, L. Dirson158, A. Djannati-Ataï159, A. Dmytriiev150, A. Donath138, V. Doroshenko149, C. Duffy160, J. Dyks161, K. Egberts162, F. Eichhorn153, S. Einecke157, G. Emery151, J.-P. Ernenwein140, K. Feijen157, S. Fegan136, A. Fiasson141, G. Fichet de Clairfontaine150, G. Fontaine136, S. Funk153, M. Füßling146, S. Gabici159, Y. A. Gallant163, G. Giavitto146, L. Giunti143,159, D. Glawion153,*, J. F. Glicenstein143, D. Gottschall149, M.-H. Grondin156, J. Hahn138, M. Haupt146, G. Hermann138, J. A. Hinton138, W. Hofmann138, C. Hoischen162, T. L. Holch164, M. Holler165, M. Hörbe142, D. Horns158, D. Huber165, M. Jamrozy147, D. Jankowsky153, F. Jankowsky166, A. Jardin-Blicq138, V. Joshi153, I. Jung-Richardt153, E. Kasai144, M. A. Kastendieck158, K. Katarzyński167, U. Katz153, D. Khangulyan168, B. Khélifi159, S. Klepser146, W. Kluźniak161, Nu. Komin155, R. Konno146, K. Kosack143, D. Kostunin146, M. Kreter6, G. Lamanna141, A. Lemière159, M. Lemoine-Goumard156, J.-P. Lenain151, C. Levy151, T. Lohse164, I. Lypova146, J. Mackey137, J. Majumdar146, D. Malyshev149, D. Malyshev153, V. Marandon138, P. Marchegiani155, A. Marcowith163, A. Mares156, G. Martí-Devesa165, R. Marx166,138, G. Maurin141, P. J. Meintjes169, M. Meyer153, R. Moderski161, M. Mohamed166, L. Mohrmann153, A. Montanari143, C. Moore160, P. Morris142, E. Moulin143, J. Muller136, T. Murach146, K. Nakashima153, A. Nayerhoda145, M. de Naurois136, H. Ndiyavala6, F. Niederwanger165, J. Niemiec145, L. Oakes164, P. O’Brien160, H. Odaka170, S. Ohm146, L. Olivera-Nieto138, E. de Ona Wilhelmi146, M. Ostrowski147, M. Panter138, S. Panny165, R. D. Parsons164, G. Peron138, B. Peyaud143, Q. Piel141, S. Pita159, V. Poireau141, A. Priyana Noel147, D. A. Prokhorov152, H. Prokoph146, G. Pühlhofer149,*, M. Punch148,159, A. Quirrenbach166, R. Rauth165, P. Reichherzer143, A. Reimer165, O. Reimer165, Q. Remy138, M. Renaud163, F. Rieger138, L. Rinchiuso143, C. Romoli138, G. Rowell157, B. Rudak161, E. Ruiz-Velasco138, V. Sahakian171, S. Sailer138, D. A. Sanchez141,*, A. Santangelo149, M. Sasaki153, M. Scalici149, H. M. Schutte6, U. Schwanke164, S. Schwemmer166, M. Seglar-Arroyo143, M. Senniappan148, A. S. Seyffert6, N. Shafi155, K. Shiningayamwe144, R. Simoni152, A. Sinha159, H. Sol150, A. Specovius153, S. Spencer142, M. Spir-Jacob159, Ł. Stawarz147, L. Sun152, R. Steenkamp144, C. Stegmann146,162, S. Steinmassl138, C. Steppa162, T. Takahashi172, T. Tavernier143, A. M. Taylor146, R. Terrier159, D. Tiziani153, M. Tluczykont158, L. Tomankova153, C. Trichard136, M. Tsirou163, R. Tuffs138, Y. Uchiyama168, D. J. van der Walt6, C. van Eldik153, C. van Rensburg6, B. van Soelen169, G. Vasileiadis163, J. Veh153, C. Venter6, P. Vincent151, J. Vink152, H. J. Völk138, T. Vuillaume141, Z. Wadiasingh6, S. J. Wagner166, J. Watson142, F. Werner138, R. White138, A. Wierzcholska145,166, Yu Wun Wong153, A. Yusafzai153, M. Zacharias6,150, R. Zanin138, D. Zargaryan137,139, A. A. Zdziarski161, A. Zech150, S. J. Zhu146, J. Zorn138, S. Zouari159, N. Żywucka6 MAGIC Collaboration V. A. Acciari173, S. Ansoldi174, L. A. Antonelli175, A. Arbet Engels176, M. Artero177, K. Asano178, D. Baack179, A. Babić180, A. Baquero181, U. Barres de Almeida182, J. A. Barrio181, J. Becerra González173, W. Bednarek183, L. Bellizzi184, E. Bernardini185, M. Bernardos186, A. Berti187, J. Besenrieder188, W. Bhattacharyya185, C. Bigongiari175, A. Biland176, O. Blanch177, G. Bonnoli184, Ž. Bošnjak180, G. Busetto186, R. Carosi189, G. Ceribella188, M. Cerruti190, Y. Chai188, A. Chilingarian191, S. Cikota180, S. M. Colak177, E. Colombo173, J. L. Contreras181, J. Cortina192, S. Covino175, G. D’Amico188, V. D’Elia175, P. Da Vela189,239, F. Dazzi175, A. De Angelis186, B. De Lotto174, M. Delfino177,240, J. Delgado177,240, C. Delgado Mendez192, D. Depaoli187, F. Di Pierro187, L. Di Venere193, E. Do Souto Espiñeira177, D. Dominis Prester194, A. Donini174, D. Dorner195, M. Doro186, D. Elsaesser179, V. Fallah Ramazani196, A. Fattorini179, G. Ferrara175, M. V. Fonseca181, L. Font197, C. Fruck188, S. Fukami178, R. J. García López173, M. Garczarczyk185, S. Gasparyan198, M. Gaug197, N. Giglietto193, F. Giordano193, P. Gliwny183, N. Godinović199, J. G. Green175, D. Green188, D. Hadasch178, A. Hahn188,†, L. Heckmann188, J. Herrera173, J. Hoang181, D. Hrupec200, M. Hütten188, T. Inada178, S. Inoue201, K. Ishio188, Y. Iwamura178, I. Jiménez192, J. Jormanainen196, L. Jouvin177, Y. Kajiwara202, M. Karjalainen173, D. Kerszberg177, Y. Kobayashi178, H. Kubo202, J. Kushida203, A. Lamastra175, D. Lelas199, F. Leone175, E. Lindfors196, S. Lombardi175, F. Longo174,241, R. López-Coto186, M. López-Moya181, A. López-Oramas173, S. Loporchio193, B. Machado de Oliveira Fraga182, C. Maggio197, P. Majumdar204, M. Makariev205, M. Mallamaci186, G. Maneva205, M. Manganaro194, K. Mannheim195, L. Maraschi175, M. Mariotti186, M. Martínez177, D. Mazin178,188,†, S. Menchiari184, S. Mender179, S. Mićanović194, D. Miceli174, T. Miener181, M. Minev205, J. M. Miranda184, R. Mirzoyan188, E. Molina190, A. Moralejo177, D. Morcuende181, V. Moreno197, E. Moretti177, V. Neustroev206, C. Nigro177, K. Nilsson196, K. Nishijima203, K. Noda178, S. Nozaki202, Y. Ohtani178, T. Oka202, J. Otero-Santos173, S. Paiano175, M. Palatiello174, D. Paneque188, R. Paoletti184, J. M. Paredes190, L. Pavletić194, P. Peñil181, C. Perennes186, M. Persic174,242, P. G. Prada Moroni189, E. Prandini186, C. Priyadarshi177, I. Puljak199, W. Rhode179, M. Ribó190, J. Rico177, C. Righi175, A. Rugliancich189, L. Saha181, N. Sahakyan198, T. Saito178, S. Sakurai178, K. Satalecka185, F. G. Saturni175, B. Schleicher195, K. Schmidt179, T. Schweizer188, J. Sitarek183, I. Šnidarić207, D. Sobczynska183, A. Spolon186, A. Stamerra175, D. Strom188, M. Strzys178, Y. Suda188, T. Surić207, M. Takahashi178, F. Tavecchio175, P. Temnikov205, T. Terzić194, M. Teshima178,188, L. Tosti208, S. Truzzi184, A. Tutone175, S. Ubach197, J. van Scherpenberg188, G. Vanzo173, M. Vazquez Acosta173, S. Ventura184, V. Verguilov205, C. F. Vigorito187, V. Vitale209, I. Vovk178, M. Will188, C. Wunderlich184, D. Zarić199 VERITAS Collaboration C.B. Adams210, W. Benbow18, A. Brill211, M. Capasso210, J. L. Christiansen212, A. J. Chromey213, M. K. Daniel18, M. Errando214, K. A Farrell215, Q. Feng210, J. P. Finley216, L. Fortson217, A. Furniss218, A. Gent219, C. Giuri220, T. Hassan220, O. Hervet221, J. Holder222, G. Hughes18, T. B. Humensky211, W. Jin223,‡, P. Kaaret224, M. Kertzman225, D. Kieda226, S. Kumar13, M. J. Lang227, M. Lundy13, G. Maier220, P. Moriarty227, R. Mukherjee210, D. Nieto228, M. Nievas-Rosillo220, S. O’Brien13, R. A. Ong229, A. N. Otte219, S. Patel224, K. Pfrang220, M. Pohl230, R. R. Prado220, E. Pueschel220, J. Quinn215, K. Ragan13, P. T. Reynolds231, D. Ribeiro211, G. T. Richards222, E. Roache18, C. Rulten217, J. L. Ryan229, M. Santander223,‡, G. H. Sembroski216, R. Shang229, A. Weinstein213, D. A. Williams221, T. J Williamson222 EAVN Collaboration Tomoya Hirota7,21, Lang Cui26,232, Kotaro Niinuma233, Hyunwook Ro19,125, Nobuyuki Sakai19, Satoko Sawada-Satoh233, Kiyoaki Wajima19, Na Wang26,232, Xiang Liu26,232, Yoshinori Yonekura234 1Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia 2Department of Physics, Villanova University, 800 E. Lancaster Avenue, Villanova, PA 19085, USA 3Institute of Astronomy and Astrophysics, Academia Sinica, 11F of Astronomy-Mathematics Building, AS/NTU No. 1, Sec. 4, Roosevelt Rd, Taipei 10617, Taiwan, R.O.C. 4Yale Center for Astronomy & Astrophysics, 52 Hillhouse Avenue, New Haven, CT 06511, USA 5Department of Physics, Yale University, P.O. Box 2018120, New Haven, CT 06520, USA 6Centre for Space Research, North-West University, Potchefstroom 2520, South Africa 7Department of Astronomical Science, The Graduate University for Advanced Studies (SOKENDAI), 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan 8Mizusawa VLBI Observatory, 2-12 Hoshigaoka, Mizusawa, Oshu, Iwate 023-0861, Japan 9525 Davey Laboratory, Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802, USA 10INAF Istituto di Radioastronomia, Via P. Gobetti, 101, I-40129 Bologna, Italy 11Department of Astrophysics, Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Radboud University, P.O. Box 9010, 6500 GL Nijmegen, The Netherlands 12Leiden Observatory—Allegro, Leiden University, P.O. Box 9513, 2300 RA Leiden, The Netherlands 13Department of Physics, McGill University, 3600 University Street, Montréal, QC H3A 2T8, Canada 14McGill Space Institute, McGill University, 3550 University Street, Montréal, QC H3A 2A7, Canada 15Institute for Astrophysical Research, Boston University, 725 Commonwealth Avenue, Boston, MA 02215, USA 16Astronomical Institute, St. Petersburg University, Universitetskij Pr. 28, Petrodvorets, 198504 St. Petersburg, Russia 17Institute for Cosmic Ray Research, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8582, Japan 18Center for Astrophysics, Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA 19Korea Astronomy and Space Science Institute, Daedeok-daero 776, Yuseong-gu, Daejeon 34055, Republic of Korea 20Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn, Germany 21National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan 22Kogakuin University of Technology & Engineering, Academic Support Center, 2665-1 Nakano, Hachioji, Tokyo 192-0015, Japan 23Moscow Institute of Physics and Technology, Institutsky per. 9, Moscow region, Dolgoprudny, 141700, Russia 24Astro Space Center, Lebedev Physical Institute, Profsouznaya 84/32, Moscow 117997, Russia 25Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030, People’s Republic of China 26Key Laboratory of Radio Astronomy, Chinese Academy of Sciences, Nanjing 210008, People’s Republic of China 27API—Anton Pannekoek Institute for Astronomy, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands 28GRAPPA—Gravitation and AstroParticle Physics Amsterdam, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands 29Physics Department, Washington University CB 1105, St Louis, MO 63130, USA 30Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan 31Department of Physics and Astronomy, Seoul National University, Gwanak-gu, Seoul 08826, Republic of Korea 32Dipartimento di Fisica, Universitá di Trieste, I-34127 Trieste, Italy 33Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34127 Trieste, Italy 34Astronomy Department, Universidad de Concepción, Casilla 160-C, Concepción, Chile 35University of Michigan, 1085 S. University Ave., Ann Arbor, MI 48109, USA 36Hiroshima Astrophysical Science Center, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan 37Saint Petersburg State University, 7/9, Universitetskaya nab., St. Petersburg, 199034, Russia 38Special Astrophysical Observatory, Russian Academy of Science, Nizhnii Arkhyz 369167, Russia 39Massachusetts Institute of Technology Haystack Observatory, 99 Millstone Road, Westford, MA 01886, USA 40Black Hole Initiative at Harvard University, 20 Garden Street, Cambridge, MA 02138, USA 41Instituto de Astrofísica de Andalucía-CSIC, Glorieta de la Astronomía s/n, E-18008 Granada, Spain 42Center for Computational Astrophysics, Flatiron Institute, 162 Fifth Avenue, New York, NY 10010, USA 43Departament d’Astronomia i Astrofísica, Universitat de València, C. Dr. Moliner 50, E-46100 Burjassot, València, Spain 44Observatori Astronòmic, Universitat de València, C. Catedrático José Beltrán 2, E-46980 Paterna, València, Spain 45Steward Observatory and Department of Astronomy, University of Arizona, 933 N. Cherry Ave., Tucson, AZ 85721, USA 46East Asian Observatory, 660 N. A’ohoku Place, Hilo, HI 96720, USA 47Fermi National Accelerator Laboratory, MS209, P.O. Box 500, Batavia, IL 60510, USA 48Department of Astronomy and Astrophysics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637, USA 49Nederlandse Onderzoekschool voor Astronomie (NOVA), P.O. Box 9513, 2300 RA Leiden, The Netherlands 50California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA 51Institute of Astronomy and Astrophysics, Academia Sinica, 645 N. A’ohoku Place, Hilo, HI 96720, USA 52Institut de Radioastronomie Millimétrique, 300 rue de la Piscine, F-38406 Saint Martin d’Hères, France 53Perimeter Institute for Theoretical Physics, 31 Caroline Street North, Waterloo, ON, N2L 2Y5, Canada 54Department of Physics and Astronomy, University of Waterloo, 200 University Avenue West, Waterloo, ON, N2L 3G1, Canada 55Waterloo Centre for Astrophysics, University of Waterloo, Waterloo, ON N2L 3G1 Canada 56University of Science and Technology, Gajeong-ro 217, Yuseong-gu, Daejeon 34113, Republic of Korea 57Kavli Institute for Cosmological Physics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637, USA 58Department of Physics, University of Chicago, 5720 South Ellis Avenue, Chicago, IL 60637, USA 59Enrico Fermi Institute, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637, USA 60Princeton Center for Theoretical Science, Jadwin Hall, Princeton University, Princeton, NJ 08544, USA 61Data Science Institute, University of Arizona, 1230 N. Cherry Ave., Tucson, AZ 85721, USA 62Cornell Center for Astrophysics and Planetary Science, Cornell University, Ithaca, NY 14853, USA 63Anton Pannekoek Institute for Astronomy, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands 64Physics Department, Fairfield University, 1073 North Benson Road, Fairfield, CT 06824, USA 65Department of Space, Earth and Environment, Chalmers University of Technology, Onsala Space Observatory, SE-43992 Onsala, Sweden 66Institut für Theoretische Physik, Goethe-Universität Frankfurt, Max-von-Laue-Straße 1, D-60438 Frankfurt am Main, Germany 67Department of Astronomy and Columbia Astrophysics Laboratory, Columbia University, 550 W 120th Street, New York, NY 10027, USA 68Dipartimento di Fisica “E. Pancini”, Universitá di Napoli “Federico II,” Compl. Univ. di Monte S. Angelo, Edificio G, Via Cinthia, I-80126, Napoli, Italy 69INFN Sez. di Napoli, Compl. Univ. di Monte S. Angelo, Edificio G, Via Cinthia, I-80126, Napoli, Italy 70Wits Centre for Astrophysics, University of the Witwatersrand, 1 Jan Smuts Avenue, Braamfontein, Johannesburg 2050, South Africa 71Department of Physics, University of Pretoria, Hatfield, Pretoria 0028, South Africa 72Centre for Radio Astronomy Techniques and Technologies, Department of Physics and Electronics, Rhodes University, Makhanda 6140, South Africa 73LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université de Paris, 5 place Jules Janssen, F-92195 Meudon, France 74JILA and Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, CO 80309, USA 75National Astronomi