article Open AccessTop 1% cited

First Sagittarius A* Event Horizon Telescope Results. VI. Testing the Black Hole Metric

The Astrophysical Journal Letters · 2022 · Vol. 930(2) · pp. L17–L17

Kazunori Akiyama✉A. Alberdi(Woodwell Climate Research Center)W. Alef(Instituto de Astrofísica de Andalucía)Juan Carlos Algaba(Max Planck Institute for Radio Astronomy)Richard Anantua(University of Malaya)Keiichi Asada(Woodwell Climate Research Center)Rebecca Azulay(Institute of Astronomy and Astrophysics, Academia Sinica)U. Bach(Universitat de València)Anne-Kathrin Baczko(Max Planck Institute for Radio Astronomy)David Ball(Max Planck Institute for Radio Astronomy)Mislav Baloković(University of Arizona)John Barrett(Yale University)Michi Bauböck(Massachusetts Institute of Technology)B. A. Benson(University of Illinois Urbana-Champaign)Dan Bintley(Fermi National Accelerator Laboratory)Lindy Blackburn(East Asian Observatory)R. Blundell(Woodwell Climate Research Center)Katherine L. Bouman(Center for Astrophysics Harvard & Smithsonian)Geoffrey C. Bower(California Institute of Technology)Hope Boyce(University of Hawaiʻi at Mānoa)Michael Bremer(McGill University)Christiaan D. Brinkerink(Institut de Radioastronomie Millimétrique)Roger Brissenden(Radboud University Nijmegen)S. Britzen(Woodwell Climate Research Center)Avery E. Broderick(Max Planck Institute for Radio Astronomy)Dominique Broguière(University of Waterloo)Thomas Bronzwaer(Institut de Radioastronomie Millimétrique)Sandra Bustamante(Radboud University Nijmegen)Do‐Young Byun(University of Massachusetts Amherst)J. E. Carlstrom(Korea Astronomy and Space Science Institute)Chiara Ceccobello(Fermi National Accelerator Laboratory)Andrew Chael(Chalmers University of Technology)Chi‐kwan Chan(Albert Einstein College of Medicine)Koushik Chatterjee(University of Arizona)Shami Chatterjee(Woodwell Climate Research Center)Ming‐Tang Chen(Cornell University)Xiaopeng ChengXiaopeng Cheng(Chinese Academy of Sciences)Ilje Cho(Korea Astronomy and Space Science Institute)Pierre Christian(Instituto de Astrofísica de Andalucía)Nicholas S. Conroy(Fairfield University)J. E. Conway(University of Illinois Urbana-Champaign)J. M. Cordes(Chalmers University of Technology)T. M. Crawford(Cornell University)G. Crew(University of Chicago)Alejandro Cruz-Osorio(Massachusetts Institute of Technology)Yuzhu Cui(Goethe University Frankfurt)Jordy Davelaar(The Graduate University for Advanced Studies, SOKENDAI)Mariafelicia De Laurentis(Radboud University Nijmegen)Roger Deane(Goethe University Frankfurt)Jessica Dempsey(University of the Witwatersrand)G. Desvignes(AstroTec Holding (Netherlands))Jason Dexter(Centre National de la Recherche Scientifique)Vedant Dhruv(Joint Institute for Laboratory Astrophysics)Sheperd S. Doeleman(University of Illinois Urbana-Champaign)Sean Dougal(Woodwell Climate Research Center)Sergio A. Dzib(University of Arizona)Ralph P. Eatough(Institut de Radioastronomie Millimétrique)Razieh Emami(Chinese Academy of Sciences)H. Falcke(Center for Astrophysics Harvard & Smithsonian)Joseph Farah(Radboud University Nijmegen)Vincent L. Fish(Las Cumbres Observatory Global Telescope Network)Ed Fomalont(Massachusetts Institute of Technology)H. Alyson Ford(National Radio Astronomy Observatory)Raquel Fraga-Encinas(University of Arizona)William T. Freeman(Radboud University Nijmegen)Per Friberg(Google (United States))Christian M. Fromm(East Asian Observatory)Antonio Fuentes(Goethe University Frankfurt)Peter Galison(Instituto de Astrofísica de Andalucía)Charles F. Gammie(Woodwell Climate Research Center)Roberto García(University of Illinois Urbana-Champaign)Olivier Gentaz(Institut de Radioastronomie Millimétrique)Boris Georgiev(Institut de Radioastronomie Millimétrique)C. Goddi(University of Waterloo)Roman Gold(University of Cagliari)Arturo I. Gómez-Ruiz(Goethe University Frankfurt)José L. Gómez(National Institute of Astrophysics, Optics and Electronics)Minfeng Gu(Instituto de Astrofísica de Andalucía)Mark Gurwell(Chinese Academy of Sciences)Kazuhiro Hada(Center for Astrophysics Harvard & Smithsonian)Daryl Haggard(The Graduate University for Advanced Studies, SOKENDAI)Kari Haworth(McGill University)M. H. Hecht(Center for Astrophysics Harvard & Smithsonian)Ronald Hesper(Massachusetts Institute of Technology)Dirk Heumann(University of Groningen)Luis C. Ho(University of Arizona)Paul T. P. Ho(Peking University)Mareki Honma(Institute of Astronomy and Astrophysics, Academia Sinica)Chih-Wei L. Huang(The Graduate University for Advanced Studies, SOKENDAI)Lei Huang(Institute of Astronomy and Astrophysics, Academia Sinica)D. H. Hughes(Chinese Academy of Sciences)Shiro Ikeda(National Institute of Astrophysics, Optics and Electronics)C. M. Violette Impellizzeri(Kavli Institute for the Physics and Mathematics of the Universe)Makoto Inoue(Leiden University)Sara Issaoun(Institute of Astronomy and Astrophysics, Academia Sinica)D. J. James(Albert Einstein College of Medicine)Buell T. Jannuzi(Whale Center of New England)Michaël Janssen(University of Arizona)Britton Jeter(Max Planck Institute for Radio Astronomy)Wu Jiang(Institute of Astronomy and Astrophysics, Academia Sinica)Alejandra Jiménez-Rosales(Shanghai Astronomical Observatory)Michael D. Johnson(Radboud University Nijmegen)Svetlana G. Jorstad(Woodwell Climate Research Center)Abhishek V. Joshi(Boston University)Taehyun Jung(University of Illinois Urbana-Champaign)Mansour Karami(Korea Astronomy and Space Science Institute)R. Karuppusamy(University of Waterloo)Tomohisa Kawashima(Max Planck Institute for Radio Astronomy)Garrett K. Keating(The University of Tokyo)Mark Kettenis(Center for Astrophysics Harvard & Smithsonian)Dong-Jin Kim(Joint Institute for VLBI ERIC)Jae-Young Kim(Max Planck Institute for Radio Astronomy)Jongsoo Kim(Korea Astronomy and Space Science Institute)Junhan Kim(Korea Astronomy and Space Science Institute)Motoki Kino(California Institute of Technology)Jun Yi Koay(Kogakuin University)Prashant Kocherlakota(Institute of Astronomy and Astrophysics, Academia Sinica)Yutaro Kofuji(Goethe University Frankfurt)Patrick M. Koch(National Astronomical Observatory of Japan)Shoko Koyama(Institute of Astronomy and Astrophysics, Academia Sinica)C. Krämer(Institute of Astronomy and Astrophysics, Academia Sinica)M. Krämer(Institut de Radioastronomie Millimétrique)T. P. Krichbaum(Max Planck Institute for Radio Astronomy)Cheng‐Yu Kuo(Max Planck Institute for Radio Astronomy)Noemi La Bella(Institute of Astronomy and Astrophysics, Academia Sinica)Tod R. Lauer(Radboud University Nijmegen)Daeyoung Lee(Kitt Peak National Observatory)Sang-Sung Lee(University of Illinois Urbana-Champaign)Po Kin Leung(Korea Astronomy and Space Science Institute)Aviad Levis(Chinese University of Hong Kong)Zhiyuan 志远 Li 李(California Institute of Technology)Rocco Lico(Nanjing University)Greg Lindahl(Istituto di Radioastronomia di Bologna)M. Lindqvist(Center for Astrophysics Harvard & Smithsonian)Mikhail Lisakov(Chalmers University of Technology)Jun 俊 Liu 刘(Max Planck Institute for Radio Astronomy)Kuo Liu(Max Planck Institute for Radio Astronomy)Elisabetta Liuzzo(Max Planck Institute for Radio Astronomy)Wen-Ping Lo(Istituto di Radioastronomia di Bologna)A. P. Lobanov(Institute of Astronomy and Astrophysics, Academia Sinica)Laurent Loinard(Max Planck Institute for Radio Astronomy)C. J. Lonsdale(Universidad Nacional Autónoma de México)Ru-Sen Lu(Massachusetts Institute of Technology)Jirong 基荣 Mao 毛(Chinese Academy of Sciences)N. Marchili(Chinese Academy of Sciences)Sera Markoff(Istituto di Radioastronomia di Bologna)Daniel P. Marrone(University of Amsterdam)Alan P. Marscher(University of Arizona)I. Martí‐Vidal(Boston University)Satoki Matsushita(Universitat de València)Lynn D. Matthews(Institute of Astronomy and Astrophysics, Academia Sinica)Lia Medeiros(Massachusetts Institute of Technology)K. M. Menten(University of Arizona)Daniel Michalik(Max Planck Institute for Radio Astronomy)Izumi Mizuno(University of Chicago)Yosuke Mizuno(East Asian Observatory)J. M. Moran(Goethe University Frankfurt)Kotaro Moriyama(Woodwell Climate Research Center)Monika Mościbrodzka(Goethe University Frankfurt)Cornelia Müller(Radboud University Nijmegen)Alejandro Mus(Radboud University Nijmegen)Gibwa Musoke(Universitat de València)I. Myserlis(Radboud University Nijmegen)Andrew Nadolski(Instituto de Radioastronomía Milimétrica)Hiroshi Nagai(University of Illinois Urbana-Champaign)Neil M. Nagar(The Graduate University for Advanced Studies, SOKENDAI)Masanori Nakamura(University of Concepción)Ramesh Narayan(Institute of Astronomy and Astrophysics, Academia Sinica)Gopal Narayanan(Woodwell Climate Research Center)Iniyan Natarajan(University of Massachusetts Amherst)Antonios Nathanail(University of the Witwatersrand)Santiago Navarro Fuentes(Goethe University Frankfurt)Joey Neilsen(Instituto de Radioastronomía Milimétrica)R. Neri(Villanova University)Chunchong Ni(Institut de Radioastronomie Millimétrique)A. Noutsos(University of Waterloo)Michael A. Nowak(Max Planck Institute for Radio Astronomy)Junghwan Oh(Washington University in St. Louis)Hiroki Okino(Sejong University)Héctor Olivares(National Astronomical Observatory of Japan)Gisela N. Ortiz-León(Radboud University Nijmegen)Tomoaki Oyama(Max Planck Institute for Radio Astronomy)Feryal Özel(National Astronomical Observatory of Japan)Daniel C. M. Palumbo(University of Arizona)Georgios Filippos Paraschos(Woodwell Climate Research Center)Jongho Park(Max Planck Institute for Radio Astronomy)Harriet Parsons(Institute of Astronomy and Astrophysics, Academia Sinica)Nimesh Patel(East Asian Observatory)Ue‐Li Pen(Center for Astrophysics Harvard & Smithsonian)Dominic W. Pesce(Canadian Institute for Advanced Research)Vincent Piétu(Woodwell Climate Research Center)R. L. Plambeck(Institut de Radioastronomie Millimétrique)Aleksandar PopStefanija(University of California, Berkeley)Oliver Porth(University of Massachusetts Amherst)Felix M. Pötzl(Goethe University Frankfurt)Ben Prather(University College Cork)Jorge A. Preciado-López(University of Illinois Urbana-Champaign)Dimitrios Psaltis(Perimeter Institute)Hung-Yi Pu(University of Arizona)Venkatessh Ramakrishnan(Institute of Astronomy and Astrophysics, Academia Sinica)Ramprasad Rao(University of Turku)Mark G. Rawlings(Center for Astrophysics Harvard & Smithsonian)Alexander W. Raymond(Gemini North Observatory)Luciano Rezzolla(Woodwell Climate Research Center)Angelo Ricarte(Goethe University Frankfurt)Bart Ripperda(Woodwell Climate Research Center)Freek Roelofs(Princeton University)A. E. E. Rogers(Woodwell Climate Research Center)E. Ros(Massachusetts Institute of Technology)Cristina Romero-Cañizales(Max Planck Institute for Radio Astronomy)Arash Roshanineshat(Institute of Astronomy and Astrophysics, Academia Sinica)Helge Rottmann(University of Arizona)A. L. Roy(Max Planck Institute for Radio Astronomy)Ignacio Ruiz(Max Planck Institute for Radio Astronomy)Chet Ruszczyk(Instituto de Radioastronomía Milimétrica)K. L. J. Rygl(Massachusetts Institute of Technology)Salvador Sánchez(Istituto di Radioastronomia di Bologna)David Sánchez-Argüelles(Instituto de Radioastronomía Milimétrica)M. Sánchez‐Portal(National Institute of Astrophysics, Optics and Electronics)Mahito Sasada(Instituto de Radioastronomía Milimétrica)Kaushik Satapathy(Hiroshima University)T. Savolainen(University of Arizona)F. Peter Schloerb(Max Planck Institute for Radio Astronomy)Jonathan Schonfeld(University of Massachusetts Amherst)K. Schüster(Center for Astrophysics Harvard & Smithsonian)Lijing Shao(Institut de Radioastronomie Millimétrique)Zhi-Qiang Shen(Peking University)Des Small(Chinese Academy of Sciences)Bong Won Sohn(Joint Institute for VLBI ERIC)Jason Soohoo(Yonsei University)Kamal Souccar(Massachusetts Institute of Technology)He Sun(University of Massachusetts Amherst)Fumie Tazaki(California Institute of Technology)Alexandra J. Tetarenko(National Astronomical Observatory of Japan)Paul Tiede(Texas Tech University)R. P. J. Tilanus(Woodwell Climate Research Center)Michael Titus(Leiden University)Pablo Torné(Massachusetts Institute of Technology)Efthalia Traianou(Instituto de Radioastronomía Milimétrica)Tyler Trent(Max Planck Institute for Radio Astronomy)Sascha Trippe(University of Arizona)Matthew Turk(Seoul National University)Ilse van Bemmel(University of Illinois Urbana-Champaign)Huib Jan van Langevelde(Joint Institute for VLBI ERIC)Daniel R. van Rossum(Leiden University)Jesse Vos(Radboud University Nijmegen)Jan Wagner(Radboud University Nijmegen)D. Ward–Thompson(Max Planck Institute for Radio Astronomy)J. F. C. Wardle(University of Lancashire)Jonathan Weintroub(Brandeis University)Norbert Wex(Woodwell Climate Research Center)Robert Wharton(Max Planck Institute for Radio Astronomy)Maciek Wielgus(Max Planck Institute for Radio Astronomy)K. Wiik(Max Planck Institute for Radio Astronomy)Gunther Witzel(University of Turku)Michael F. Wondrak(Max Planck Institute for Radio Astronomy)George N. Wong(Radboud University Nijmegen)Qingwen 庆文 Wu 吴(Princeton University)Paul Yamaguchi(Huazhong University of Science and Technology)Doosoo Yoon(Center for Astrophysics Harvard & Smithsonian)André Young(University of Amsterdam)Ken Young(Radboud University Nijmegen)Ziri Younsi(Center for Astrophysics Harvard & Smithsonian)Feng 峰 Yuan 袁(Goethe University Frankfurt)Ye-Fei 业飞 Yuan 袁(Shanghai Astronomical Observatory)J. A. Zensus(University of Science and Technology of China)Shuo Zhang(Max Planck Institute for Radio Astronomy)Guang-Yao Zhao(Bard College)Shan-Shan Zhao(Instituto de Astrofísica de Andalucía)

View via DOI Full-text PDF

Abstract

Abstract Astrophysical black holes are expected to be described by the Kerr metric. This is the only stationary, vacuum, axisymmetric metric, without electromagnetic charge, that satisfies Einstein’s equations and does not have pathologies outside of the event horizon. We present new constraints on potential deviations from the Kerr prediction based on 2017 EHT observations of Sagittarius A* (Sgr A*). We calibrate the relationship between the geometrically defined black hole shadow and the observed size of the ring-like images using a library that includes both Kerr and non-Kerr simulations. We use the exquisite prior constraints on the mass-to-distance ratio for Sgr A* to show that the observed image size is within ∼10% of the Kerr predictions. We use these bounds to constrain metrics that are parametrically different from Kerr, as well as the charges of several known spacetimes. To consider alternatives to the presence of an event horizon, we explore the possibility that Sgr A* is a compact object with a surface that either absorbs and thermally reemits incident radiation or partially reflects it. Using the observed image size and the broadband spectrum of Sgr A*, we conclude that a thermal surface can be ruled out and a fully reflective one is unlikely. We compare our results to the broader landscape of gravitational tests. Together with the bounds found for stellar-mass black holes and the M87 black hole, our observations provide further support that the external spacetimes of all black holes are described by the Kerr metric, independent of their mass.

Astrophysical Phenomena and Observations Pulsars and Gravitational Waves Research Astrophysics and Cosmic PhenomenaEvent horizonSagittarius A*Black hole (networking)Metric (unit)HorizonPhysicsAstrophysicsTelescopeEvent (particle physics)Astronomy

Funding

National Science Foundation
Smithsonian Institution
U.S. Department of Energy
National Aeronautics and Space Administration
Simons Foundation
John Templeton Foundation
Gordon and Betty Moore Foundation
University of Chicago
University of Arizona
National Center for Theoretical Sciences
Compute Canada
Netherlands eScience Center
Space Telescope Science Institute
Ministerio de Ciencia, Innovación y Universidades
National Radio Astronomy Observatory
Associated Universities
International Max Planck Research School for Environmental, Cellular and Molecular Microbiology
Joint Institute for Computational Fundamental Science
Flatiron Health
Government of Canada
Leverhulme Trust
European Commission
National Research Foundation
University of Pretoria
Deutsche Forschungsgemeinschaft
Ministry of Education, Culture, Sports, Science and Technology
Universiteit Leiden
National Natural Science Foundation of China
Universiteit van Amsterdam
Radboud Universiteit
Academia Sinica
Academy of Finland
Chinese Academy of Sciences
China Postdoctoral Science Foundation
Consejo Nacional de Ciencia y Tecnología
Nederlandse Organisatie voor Wetenschappelijk Onderzoek
Generalitat Valenciana
Nuclear Safety and Security Commission
Korea Astronomy and Space Science Institute
National Research Foundation of Korea
Max-Planck-Gesellschaft
Vetenskapsrådet
Ministry of Education, India
China Scholarship Council
European Southern Observatory
Centre National de la Recherche Scientifique
Ministerio de Ciencia e Innovación
Shanghai Jiao Tong University
Universidad Nacional Autónoma de México
National Astronomical Observatory of Japan
Recruitment Program of Global Experts
Junta de Andalucía
Istituto Nazionale di Fisica Nucleare
Ministry of Science and ICT, South Korea
Instituto de Astrofísica de Andalucía
Agencia Nacional de Investigación y Desarrollo
Institut Périmètre de physique théorique
East Asian Core Observatories Association
Toray Science Foundation
Office of Science
National Nuclear Security Administration
Physics Division, National Center for Theoretical Sciences
Natural Sciences and Engineering Research Council of Canada
Science and Technology Facilities Council
Japan Society for the Promotion of Science
Consejo Superior de Investigaciones Científicas
Dirección General de Asuntos del Personal Académico, Universidad Nacional Autónoma de México
National Institutes of Natural Sciences
National Key Research and Development Program of China
Office of International Science and Engineering
Oak Ridge National Laboratory
Los Alamos National Laboratory