First Sagittarius A* Event Horizon Telescope Results. VI. Testing the Black Hole Metric
Journal article, 2022
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 similar to 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.
Author
Kazunori Akiyama
Massachusetts Institute of Technology (MIT)
Harvard University
National Astronomical Observatory of Japan
Antxon Alberdi
Spanish National Research Council (CSIC)
Walter Alef
Max Planck Society
Juan Carlos Algaba
University of Malaya
Richard Anantua
Harvard University
Harvard-Smithsonian Center for Astrophysics
University of Texas at San Antonio
Keiichi Asada
Academia Sinica
Rebecca Azulay
Universitat de Valencia
Max Planck Society
Uwe Bach
Max Planck Society
Anne-Kathrin Baczko
Max Planck Society
David Ball
University of Arizona
Mislav Balokovic
Yale University
John Barrett
Massachusetts Institute of Technology (MIT)
Michi Baubock
University of Illinois
Bradford A. Benson
Fermi National Accelerator Laboratory
University of Chicago
Dan Bintley
East Asian Observatory
James Clerk Maxwell Telescope
Lindy Blackburn
Harvard University
Harvard-Smithsonian Center for Astrophysics
Raymond Blundell
Harvard-Smithsonian Center for Astrophysics
Katherine L. Bouman
California Institute of Technology (Caltech)
Geoffrey C. Bower
Academia Sinica
University of Hawaii
Hope Boyce
McGill University
Michael Bremer
Institut de Radioastronomie Millimétrique (IRAM)
Christiaan D. Brinkerink
Radboud University
Roger Brissenden
Harvard-Smithsonian Center for Astrophysics
Harvard University
Silke Britzen
Max Planck Society
Avery E. Broderick
University of Waterloo
Perimeter Institute for Theoretical Physics
Dominique Broguiere
Institut de Radioastronomie Millimétrique (IRAM)
Thomas Bronzwaer
Radboud University
Sandra Bustamante
University of Massachusetts
Do-Young Byun
University of Science and Technology (UST)
Korea Astronomy and Space Science Institute
John E. Carlstrom
University of Chicago
Chiara Ceccobello
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
Andrew Chael
National Aeronautics and Space Administration (NASA)
Princeton University
Chi-kwan Chan
University of Arizona
Koushik Chatterjee
Harvard-Smithsonian Center for Astrophysics
Harvard University
Shami Chatterjee
Cornell University
Ming-Tang Chen
Academia Sinica
Yongjun Chen
Chinese Academy of Sciences
Xiaopeng Cheng
Korea Astronomy and Space Science Institute
Ilje Cho
Spanish National Research Council (CSIC)
Pierre Christian
Fairfield University
Nicholas S. Conroy
Harvard-Smithsonian Center for Astrophysics
University of Illinois
John Conway
Chalmers, Space, Earth and Environment, Onsala Space Observatory
James M. Cordes
Cornell University
Thomas M. Crawford
University of Chicago
Geoffrey B. Crew
Massachusetts Institute of Technology (MIT)
Alejandro Cruz-Osorio
Goethe University Frankfurt
Yuzhu Cui
National Astronomical Observatory of Japan
Shanghai Jiao Tong University
The Graduate University for Advanced Studies (SOKENDAI)
Jordy Davelaar
Columbia University
Radboud University
Flatiron Institute
Mariafelicia De Laurentis
University of Naples Federico II
National Institute for Nuclear Physics
Goethe University Frankfurt
Roger Deane
University of Pretoria
University of Witwatersrand
Rhodes University
Jessica Dempsey
James Clerk Maxwell Telescope
Netherlands Institute for Radio Astronomy (ASTRON)
East Asian Observatory
Gregory Desvignes
Max Planck Society
Paris Descartes University
Jason Dexter
University of Colorado at Boulder
Vedant Dhruv
University of Illinois
Sheperd S. Doeleman
Harvard University
Harvard-Smithsonian Center for Astrophysics
Sean Dougal
University of Arizona
Sergio A. Dzib
Max Planck Society
Institut de Radioastronomie Millimétrique (IRAM)
Ralph P. Eatough
Chinese Academy of Sciences
Max Planck Society
Razieh Emami
Harvard-Smithsonian Center for Astrophysics
Heino Falcke
Radboud University
Joseph Farah
University of California at Santa Barbara
Las Cumbres Observatory Global Telescope Network
Vincent L. Fish
Massachusetts Institute of Technology (MIT)
Ed Fomalont
National Radio Astronomy Observatory
H. Alyson Ford
University of Arizona
Raquel Fraga-Encinas
Radboud University
William T. Freeman
Massachusetts Institute of Technology (MIT)
Google Inc.
Per Friberg
James Clerk Maxwell Telescope
East Asian Observatory
Christian M. Fromm
Goethe University Frankfurt
University of Würzburg
Max Planck Society
Antonio Fuentes
Spanish National Research Council (CSIC)
Peter Galison
Harvard University
Charles F. Gammie
University of Illinois
Roberto Garcia
Institut de Radioastronomie Millimétrique (IRAM)
Olivier Gentaz
Institut de Radioastronomie Millimétrique (IRAM)
Boris Georgiev
Perimeter Institute for Theoretical Physics
University of Waterloo
Ciriaco Goddi
Istituto nazionale di astrofisica (INAF)
University of Cagliari
Roman Gold
Goethe University Frankfurt
University of Southern Denmark
Gomez-Ruiz
National Institute of Astrophysics, Optics and Electronics
National Council for Science and Technology Mexico
Jose L. Gomez
Spanish National Research Council (CSIC)
Minfeng Gu
Chinese Academy of Sciences
Mark Gurwell
Harvard-Smithsonian Center for Astrophysics
Kazuhiro Hada
National Astronomical Observatory of Japan
The Graduate University for Advanced Studies (SOKENDAI)
Daryl Haggard
McGill University
Kari Haworth
Harvard-Smithsonian Center for Astrophysics
Michael H. Hecht
Massachusetts Institute of Technology (MIT)
Ronald Hesper
University of Groningen
Dirk Heumann
University of Arizona
Luis C. Ho
Beijing University of Technology
Paul Ho
James Clerk Maxwell Telescope
Academia Sinica
Mareki Honma
National Astronomical Observatory of Japan
University of Tokyo
The Graduate University for Advanced Studies (SOKENDAI)
Chih-Wei L. Huang
Academia Sinica
Lei Huang
Chinese Academy of Sciences
David H. Hughes
National Institute of Astrophysics, Optics and Electronics
Shiro Ikeda
The Graduate University for Advanced Studies (SOKENDAI)
The Institute of Statistical Mathematics
National Astronomical Observatory of Japan
University of Tokyo
C. M. Violette Impellizzeri
Leiden University
National Radio Astronomy Observatory
Makoto Inoue
Academia Sinica
Sara Issaoun
National Aeronautics and Space Administration (NASA)
Harvard-Smithsonian Center for Astrophysics
David J. James
ASTRAVEO
Buell T. Jannuzi
University of Arizona
Michael Janssen
Max Planck Society
Britton Jeter
Academia Sinica
Wu Jiang
Chinese Academy of Sciences
Alejandra Jimenez-Rosales
Radboud University
Michael D. Johnson
Harvard University
Harvard-Smithsonian Center for Astrophysics
Svetlana Jorstad
Boston University
Joshi
University of Illinois
Taehyun Jung
University of Science and Technology (UST)
Korea Astronomy and Space Science Institute
Mansour Karami
University of Waterloo
Perimeter Institute for Theoretical Physics
Ramesh Karuppusamy
Max Planck Society
Tomohisa Kawashima
University of Tokyo
Garrett K. Keating
Harvard-Smithsonian Center for Astrophysics
Mark Kettenis
Joint Institute for VLBI in Europe (JIVE)
Dong-Jin Kim
Max Planck Society
Jae-Young Kim
Max Planck Society
Kyungpook National University
Korea Astronomy and Space Science Institute
Jongsoo Kim
Korea Astronomy and Space Science Institute
Junhan Kim
University of Arizona
California Institute of Technology (Caltech)
Motoki Kino
National Astronomical Observatory of Japan
Kogakuin University of Technology and Engineering
Jun Yi Koay
Academia Sinica
Prashant Kocherlakota
Goethe University Frankfurt
Yutaro Kofuji
University of Tokyo
National Astronomical Observatory of Japan
Patrick M. Koch
Academia Sinica
Shoko Koyama
Niigata University
Academia Sinica
Carsten Kramer
Institut de Radioastronomie Millimétrique (IRAM)
Michael Kramer
Max Planck Society
Thomas P. Krichbaum
Max Planck Society
Cheng-Yu Kuo
Academia Sinica
National Sun Yat-Sen University
Noemi La Bella
Radboud University
Tod R. Lauer
National Optical Astronomy Observatory
Daeyoung Lee
University of Illinois
Sang-Sung Lee
Korea Astronomy and Space Science Institute
Po Kin Leung
Chinese University of Hong Kong
Aviad Levis
California Institute of Technology (Caltech)
Zhiyuan Li
Nanjing University
Rocco Lico
Spanish National Research Council (CSIC)
Istituto nazionale di astrofisica (INAF)
Greg Lindahl
Harvard-Smithsonian Center for Astrophysics
Michael Lindqvist
Chalmers, Space, Earth and Environment, Onsala Space Observatory
Mikhail Lisakov
Max Planck Society
Jun Liu
Max Planck Society
Kuo Liu
Max Planck Society
Elisabetta Liuzzo
Italian ALMA Regional Centre
Istituto nazionale di astrofisica (INAF)
Wen-Ping Lo
Academia Sinica
National Taiwan University
Andrei P. Lobanov
Max Planck Society
Laurent Loinard
Universidad Nacional Autónoma de México
Colin J. Lonsdale
Massachusetts Institute of Technology (MIT)
Ru-Sen Lu
Chinese Academy of Sciences
Max Planck Society
Jirong Mao
Chinese Academy of Sciences
Nicola Marchili
Istituto nazionale di astrofisica (INAF)
Italian ALMA Regional Centre
Max Planck Society
Sera Markoff
University of Amsterdam
Daniel P. Marrone
University of Arizona
Alan P. Marscher
Boston University
Ivan Marti-Vidal
Universitat de Valencia
Satoki Matsushita
Academia Sinica
Lynn D. Matthews
Massachusetts Institute of Technology (MIT)
Lia Medeiros
Institute for Advanced Study
University of Arizona
Karl M. Menten
Max Planck Society
Daniel Michalik
European Space Research and Technology Centre (ESA ESTEC)
University of Chicago
Izumi Mizuno
East Asian Observatory
James Clerk Maxwell Telescope
Yosuke Mizuno
Shanghai Jiao Tong University
Goethe University Frankfurt
James M. Moran
Harvard University
Harvard-Smithsonian Center for Astrophysics
Kotaro Moriyama
Goethe University Frankfurt
Massachusetts Institute of Technology (MIT)
National Astronomical Observatory of Japan
Monika Moscibrodzka
Radboud University
Cornelia Muller
Radboud University
Max Planck Society
Alejandro Mus
Universitat de Valencia
Gibwa Musoke
Radboud University
University of Amsterdam
Ioannis Myserlis
Institut de Radioastronomie Millimétrique (IRAM)
Andrew Nadolski
University of Illinois
Hiroshi Nagai
National Astronomical Observatory of Japan
The Graduate University for Advanced Studies (SOKENDAI)
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University of Concepcion
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Academia Sinica
National Institute of Technology, Hachinohe College
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Harvard University
Harvard-Smithsonian Center for Astrophysics
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University of Massachusetts
Iniyan Natarajan
South African Radio Astronomy Observatory (SARAO)
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Goethe University Frankfurt
National and Kapodistrian University of Athens
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Institut de Radioastronomie Millimétrique (IRAM)
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Villanova University
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Institut de Radioastronomie Millimétrique (IRAM)
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Perimeter Institute for Theoretical Physics
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Max Planck Society
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Washington University in St. Louis
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Sejong University
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National Astronomical Observatory of Japan
University of Tokyo
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Radboud University
Gisela N. Ortiz-Leon
Max Planck Society
Universidad Nacional Autónoma de México
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National Astronomical Observatory of Japan
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University of Arizona
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Harvard University
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East Asian Observatory
James Clerk Maxwell Telescope
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Harvard-Smithsonian Center for Astrophysics
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Academia Sinica
Canadian Institute for Advanced Research
Perimeter Institute for Theoretical Physics
University of Toronto
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Harvard University
Harvard-Smithsonian Center for Astrophysics
Vincent Pietu
Institut de Radioastronomie Millimétrique (IRAM)
Richard Plambeck
University of California at Berkeley
Aleksandar PopStefanija
University of Massachusetts
Oliver Porth
Goethe University Frankfurt
University of Amsterdam
Felix M. Potzl
University College Cork
Max Planck Society
Ben Prather
University of Illinois
Jorge A. Preciado-Lopez
Perimeter Institute for Theoretical Physics
Dimitrios Psaltis
University of Arizona
Hung-Yi Pu
Academia Sinica
National Taiwan Normal University
Venkatessh Ramakrishnan
University of Concepcion
University of Turku
Aalto University
Ramprasad Rao
Harvard-Smithsonian Center for Astrophysics
Mark G. Rawlings
James Clerk Maxwell Telescope
East Asian Observatory
Gemini Observatory North
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Harvard-Smithsonian Center for Astrophysics
Harvard University
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Trinity College Dublin
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Harvard-Smithsonian Center for Astrophysics
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Princeton University
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Harvard University
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Massachusetts Institute of Technology (MIT)
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Max Planck Society
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Academia Sinica
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University of Arizona
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Max Planck Society
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Max Planck Society
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Institut de Radioastronomie Millimétrique (IRAM)
Chet Ruszczyk
Massachusetts Institute of Technology (MIT)
Kazi L. J. Rygl
Italian ALMA Regional Centre
Istituto nazionale di astrofisica (INAF)
Salvador Sanchez
Institut de Radioastronomie Millimétrique (IRAM)
David Sanchez-Arguelles
National Council for Science and Technology Mexico
National Institute of Astrophysics, Optics and Electronics
Miguel Sanchez-Portal
Institut de Radioastronomie Millimétrique (IRAM)
Mahito Sasada
Tokyo Institute of Technology
National Astronomical Observatory of Japan
Hiroshima University
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University of Arizona
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Aalto University
Max Planck Society
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University of Massachusetts
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Harvard-Smithsonian Center for Astrophysics
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Institut de Radioastronomie Millimétrique (IRAM)
Lijing Shao
Max Planck Society
Beijing University of Technology
Zhiqiang Shen
Chinese Academy of Sciences
Des Small
Joint Institute for VLBI in Europe (JIVE)
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Korea Astronomy and Space Science Institute
University of Science and Technology (UST)
James Clerk Maxwell Telescope
Yonsei University
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Massachusetts Institute of Technology (MIT)
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University of Massachusetts
He Sun
California Institute of Technology (Caltech)
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National Astronomical Observatory of Japan
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National Aeronautics and Space Administration (NASA)
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Harvard University
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Massachusetts Institute of Technology (MIT)
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Institut de Radioastronomie Millimétrique (IRAM)
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Spanish National Research Council (CSIC)
Max Planck Society
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University of Arizona
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Seoul National University
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University of Illinois
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Joint Institute for VLBI in Europe (JIVE)
Huib Jan van Langevelde
Joint Institute for VLBI in Europe (JIVE)
Leiden University
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Radboud University
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Radboud University
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Max Planck Society
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University of Central Lancashire
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Brandeis University
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Harvard University
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Max Planck Society
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Max Planck Society
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University of Turku
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Max Planck Society
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Radboud University
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Institute for Advanced Study
Princeton University
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Huazhong University of Science and Technology
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Harvard-Smithsonian Center for Astrophysics
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University of Amsterdam
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Radboud University
Ken Young
Harvard-Smithsonian Center for Astrophysics
Ziri Younsi
Goethe University Frankfurt
University College London (UCL)
Feng Yuan
Chinese Academy of Sciences
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East Asian Observatory
James Clerk Maxwell Telescope
University of Science and Technology of China
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Max Planck Society
Shuo Zhang
Bard College
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Spanish National Research Council (CSIC)
Shan-Shan Zhao
Chinese Academy of Sciences
Astrophysical Journal Letters
2041-8205 (ISSN) 2041-8213 (eISSN)
Vol. 930 2 L17Subject Categories (SSIF 2011)
Astronomy, Astrophysics and Cosmology
Other Physics Topics
Radiology, Nuclear Medicine and Medical Imaging
DOI
10.3847/2041-8213/ac6756