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
Harvard University
Massachusetts Institute of Technology (MIT)
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
University of Texas at San Antonio
Harvard-Smithsonian Center for Astrophysics
Harvard University
Keiichi Asada
Academia Sinica
Rebecca Azulay
Max Planck Society
Universitat de Valencia
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
James Clerk Maxwell Telescope
East Asian Observatory
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
University of Hawaii
Academia Sinica
Hope Boyce
McGill University
Michael Bremer
Institut de Radioastronomie Millimétrique (IRAM)
Christiaan D. Brinkerink
Radboud University
Roger Brissenden
Harvard University
Harvard-Smithsonian Center for Astrophysics
Silke Britzen
Max Planck Society
Avery E. Broderick
Perimeter Institute for Theoretical Physics
University of Waterloo
Dominique Broguiere
Institut de Radioastronomie Millimétrique (IRAM)
Thomas Bronzwaer
Radboud University
Sandra Bustamante
University of Massachusetts
Do-Young Byun
Korea Astronomy and Space Science Institute
University of Science and Technology (UST)
John E. Carlstrom
University of Chicago
Chiara Ceccobello
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
Andrew Chael
Princeton University
NASA Hubble Fellowship Program
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
Flatiron Institute
Radboud University
Mariafelicia De Laurentis
University of Naples Federico II
Goethe University Frankfurt
National Institute for Nuclear Physics
Roger Deane
University of Witwatersrand
Rhodes University
University of Pretoria
Jessica Dempsey
James Clerk Maxwell Telescope
East Asian Observatory
Netherlands Institute for Radio Astronomy (ASTRON)
Gregory Desvignes
Paris Descartes University
Max Planck Society
Jason Dexter
University of Colorado at Boulder
Vedant Dhruv
University of Illinois
Sheperd S. Doeleman
Harvard-Smithsonian Center for Astrophysics
Harvard University
Sean Dougal
University of Arizona
Sergio A. Dzib
Institut de Radioastronomie Millimétrique (IRAM)
Max Planck Society
Ralph P. Eatough
Chinese Academy of Sciences
Max Planck Society
Razieh Emami
Harvard-Smithsonian Center for Astrophysics
Heino Falcke
Radboud University
Joseph Farah
Las Cumbres Observatory Global Telescope Network
University of California at Santa Barbara
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
Google Inc.
Massachusetts Institute of Technology (MIT)
Per Friberg
East Asian Observatory
James Clerk Maxwell Telescope
Christian M. Fromm
Goethe University Frankfurt
Max Planck Society
University of Würzburg
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
University of Cagliari
Istituto nazionale di astrofisica (INAF)
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
University of Tokyo
National Astronomical Observatory of Japan
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 Institute of Statistical Mathematics
National Astronomical Observatory of Japan
The Graduate University for Advanced Studies (SOKENDAI)
University of Tokyo
C. M. Violette Impellizzeri
National Radio Astronomy Observatory
Leiden University
Makoto Inoue
Academia Sinica
Sara Issaoun
NASA Hubble Fellowship Program
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-Smithsonian Center for Astrophysics
Harvard University
Svetlana Jorstad
Boston University
Joshi
University of Illinois
Taehyun Jung
University of Science and Technology (UST)
Korea Astronomy and Space Science Institute
Mansour Karami
Perimeter Institute for Theoretical Physics
University of Waterloo
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
Korea Astronomy and Space Science Institute
Kyungpook National University
Jongsoo Kim
Korea Astronomy and Space Science Institute
Junhan Kim
University of Arizona
California Institute of Technology (Caltech)
Motoki Kino
Kogakuin University of Technology and Engineering
National Astronomical Observatory of Japan
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
Academia Sinica
Niigata University
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
Istituto nazionale di astrofisica (INAF)
Spanish National Research Council (CSIC)
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
Istituto nazionale di astrofisica (INAF)
Italian ALMA Regional Centre
Wen-Ping Lo
National Taiwan University
Academia Sinica
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
Italian ALMA Regional Centre
Istituto nazionale di astrofisica (INAF)
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
University of Chicago
European Space Research and Technology Centre (ESA ESTEC)
Izumi Mizuno
James Clerk Maxwell Telescope
East Asian Observatory
Yosuke Mizuno
Shanghai Jiao Tong University
Goethe University Frankfurt
James M. Moran
Harvard University
Harvard-Smithsonian Center for Astrophysics
Kotaro Moriyama
Massachusetts Institute of Technology (MIT)
Goethe University Frankfurt
National Astronomical Observatory of Japan
Monika Moscibrodzka
Radboud University
Cornelia Muller
Max Planck Society
Radboud University
Alejandro Mus
Universitat de Valencia
Gibwa Musoke
University of Amsterdam
Radboud University
Ioannis Myserlis
Institut de Radioastronomie Millimétrique (IRAM)
Andrew Nadolski
University of Illinois
Hiroshi Nagai
The Graduate University for Advanced Studies (SOKENDAI)
National Astronomical Observatory of Japan
Neil M. Nagar
University of Concepcion
Masanori Nakamura
Academia Sinica
National Institute of Technology, Hachinohe College
Ramesh Narayan
Harvard University
Harvard-Smithsonian Center for Astrophysics
Gopal Narayanan
University of Massachusetts
Iniyan Natarajan
University of Witwatersrand
South African Radio Astronomy Observatory (SARAO)
Antonios Nathanail
Goethe University Frankfurt
National and Kapodistrian University of Athens
Santiago Navarro Fuentes
Institut de Radioastronomie Millimétrique (IRAM)
Joey Neilsen
Villanova University
Roberto Neri
Institut de Radioastronomie Millimétrique (IRAM)
Chunchong Ni
University of Waterloo
Perimeter Institute for Theoretical Physics
Aristeidis Noutsos
Max Planck Society
Michael A. Nowak
Washington University in St. Louis
Junghwan Oh
Sejong University
Hiroki Okino
National Astronomical Observatory of Japan
University of Tokyo
Hector Olivares
Radboud University
Gisela N. Ortiz-Leon
Max Planck Society
Universidad Nacional Autónoma de México
Tomoaki Oyama
National Astronomical Observatory of Japan
Feryal Ozel
University of Arizona
Daniel C. M. Palumbo
Harvard University
Harvard-Smithsonian Center for Astrophysics
Georgios Filippos Paraschos
Max Planck Society
Jongho Park
Academia Sinica
Harriet Parsons
East Asian Observatory
James Clerk Maxwell Telescope
Nimesh Patel
Harvard-Smithsonian Center for Astrophysics
Ue-Li Pen
Academia Sinica
Perimeter Institute for Theoretical Physics
Canadian Institute for Advanced Research
University of Toronto
Dominic W. Pesce
Harvard-Smithsonian Center for Astrophysics
Harvard University
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
Max Planck Society
University College Cork
Ben Prather
University of Illinois
Jorge A. Preciado-Lopez
Perimeter Institute for Theoretical Physics
Dimitrios Psaltis
University of Arizona
Hung-Yi Pu
National Taiwan Normal University
Academia Sinica
Venkatessh Ramakrishnan
University of Concepcion
Aalto University
University of Turku
Ramprasad Rao
Harvard-Smithsonian Center for Astrophysics
Mark G. Rawlings
East Asian Observatory
Gemini Observatory North
James Clerk Maxwell Telescope
Alexander W. Raymond
Harvard University
Harvard-Smithsonian Center for Astrophysics
Luciano Rezzolla
Trinity College Dublin
Goethe University Frankfurt
Frankfurt Institute for Advanced Studies
Angelo Ricarte
Harvard-Smithsonian Center for Astrophysics
Harvard University
Bart Ripperda
Flatiron Institute
Princeton University
Freek Roelofs
Harvard-Smithsonian Center for Astrophysics
Harvard University
Radboud University
Alan Rogers
Massachusetts Institute of Technology (MIT)
Eduardo Ros
Max Planck Society
Cristina Romero-Canizales
Academia Sinica
Arash Roshanineshat
University of Arizona
Helge Rottmann
Max Planck Society
Alan L. Roy
Max Planck Society
Ignacio Ruiz
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 Institute of Astrophysics, Optics and Electronics
National Council for Science and Technology Mexico
Miguel Sanchez-Portal
Institut de Radioastronomie Millimétrique (IRAM)
Mahito Sasada
Tokyo Institute of Technology
National Astronomical Observatory of Japan
Hiroshima University
Kaushik Satapathy
University of Arizona
Tuomas Savolainen
Max Planck Society
Aalto University
F. Peter Schloerb
University of Massachusetts
Jonathan Schonfeld
Harvard-Smithsonian Center for Astrophysics
Karl-Friedrich Schuster
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)
Bong Won Sohn
Korea Astronomy and Space Science Institute
University of Science and Technology (UST)
East Asian Observatory
Yonsei University
James Clerk Maxwell Telescope
Jason SooHoo
Massachusetts Institute of Technology (MIT)
Kamal Souccar
University of Massachusetts
He Sun
California Institute of Technology (Caltech)
Fumie Tazaki
National Astronomical Observatory of Japan
Alexandra J. Tetarenko
NASA Hubble Fellowship Program
Texas Tech University at Lubbock
Paul Tiede
Harvard University
Harvard-Smithsonian Center for Astrophysics
Remo P. J. Tilanus
University of Arizona
Leiden University
Netherlands Organisation for Scientific Research (NWO)
Radboud University
Michael Titus
Massachusetts Institute of Technology (MIT)
Pablo Torne
Institut de Radioastronomie Millimétrique (IRAM)
Max Planck Society
Efthalia Traianou
Max Planck Society
Spanish National Research Council (CSIC)
Tyler Trent
University of Arizona
Sascha Trippe
Seoul National University
Matthew Turk
University of Illinois
Ilse van Bemmel
Joint Institute for VLBI in Europe (JIVE)
Huib Jan van Langevelde
Joint Institute for VLBI in Europe (JIVE)
Leiden University
University of New Mexico
Daniel R. van Rossum
Radboud University
Jesse Vos
Radboud University
Jan Wagner
Max Planck Society
Derek Ward-Thompson
University of Central Lancashire
John Wardle
Brandeis University
Jonathan Weintroub
Harvard University
Harvard-Smithsonian Center for Astrophysics
Norbert Wex
Max Planck Society
Robert Wharton
Max Planck Society
Maciek Wielgus
Max Planck Society
Kaj Wiik
University of Turku
Gunther Witzel
Max Planck Society
Michael F. Wondrak
Radboud University
George N. Wong
Institute for Advanced Study
Princeton University
Qingwen Wu
Huazhong University of Science and Technology
Paul Yamaguchi
Harvard-Smithsonian Center for Astrophysics
Doosoo Yoon
University of Amsterdam
Andre Young
Radboud University
Ken Young
Harvard-Smithsonian Center for Astrophysics
Ziri Younsi
University College London (UCL)
Goethe University Frankfurt
Feng Yuan
Chinese Academy of Sciences
Ye-Fei Yuan
James Clerk Maxwell Telescope
University of Science and Technology of China
East Asian Observatory
J. Anton Zensus
Max Planck Society
Shuo Zhang
Bard College
Guang-Yao Zhao
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
Astronomy, Astrophysics and Cosmology
Other Physics Topics
Radiology, Nuclear Medicine and Medical Imaging
DOI
10.3847/2041-8213/ac6756