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

National Astronomical Observatory of Japan

Harvard University

Massachusetts Institute of Technology (MIT)

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

University of Chicago

Fermi National Accelerator Laboratory

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

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

University of Illinois

Harvard-Smithsonian Center for Astrophysics

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

Shanghai Jiao Tong University

National Astronomical Observatory of Japan

The Graduate University for Advanced Studies (SOKENDAI)

Jordy Davelaar

Radboud University

Columbia University

Flatiron Institute

Mariafelicia De Laurentis

Goethe University Frankfurt

University of Naples Federico II

National Institute for Nuclear Physics

Roger Deane

University of Witwatersrand

University of Pretoria

Rhodes University

Jessica Dempsey

East Asian Observatory

James Clerk Maxwell Telescope

Netherlands Institute for Radio Astronomy (ASTRON)

Gregory Desvignes

Max Planck Society

Paris Descartes University

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

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

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

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

University of Waterloo

Perimeter Institute for Theoretical Physics

Ciriaco Goddi

INAF Osservatorio Astronomico di Cagliari

University of Cagliari

Roman Gold

University of Southern Denmark

Goethe University Frankfurt

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

The Graduate University for Advanced Studies (SOKENDAI)

National Astronomical Observatory of Japan

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

Academia Sinica

James Clerk Maxwell Telescope

Mareki Honma

The Graduate University for Advanced Studies (SOKENDAI)

National Astronomical Observatory of Japan

University of Tokyo

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

Harvard-Smithsonian Center for Astrophysics

NASA Hubble Fellowship Program

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

Korea Astronomy and Space Science Institute

University of Science and Technology (UST)

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

Korea Astronomy and Space Science Institute

Max Planck Society

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

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

Istituto nazionale di astrofisica (INAF)

Italian ALMA Regional Centre

Wen-Ping Lo

Academia Sinica

National Taiwan University

Andrei P. Lobanov

Max Planck Society

Laurent Loinard

Universidad Nacional Autonoma de Mexico

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

Max Planck Society

Istituto nazionale di astrofisica (INAF)

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

University of Arizona

Institute for Advanced Study

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-Smithsonian Center for Astrophysics

Harvard University

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

University of Amsterdam

Radboud University

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)

Neil M. Nagar

University of Concepcion

Masanori Nakamura

National Institute of Technology, Hachinohe College

Academia Sinica

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

National and Kapodistrian University of Athens

Goethe University Frankfurt

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

University of Tokyo

National Astronomical Observatory of Japan

Hector Olivares

Radboud University

Gisela N. Ortiz-Leon

Max Planck Society

Universidad Nacional Autonoma de Mexico

Tomoaki Oyama

National Astronomical Observatory of Japan

Feryal Ozel

University of Arizona

Daniel C. M. Palumbo

Harvard-Smithsonian Center for Astrophysics

Harvard University

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

University of Toronto

Canadian Institute for Advanced Research

Perimeter Institute for Theoretical Physics

Dominic W. Pesce

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

National Taiwan Normal University

Academia Sinica

Venkatessh Ramakrishnan

University of Turku

Aalto University

University of Concepcion

Ramprasad Rao

Harvard-Smithsonian Center for Astrophysics

Mark G. Rawlings

East Asian Observatory

James Clerk Maxwell Telescope

Gemini Observatory North

Alexander W. Raymond

Harvard-Smithsonian Center for Astrophysics

Harvard University

Luciano Rezzolla

Goethe University Frankfurt

Frankfurt Institute for Advanced Studies

Trinity College Dublin

Angelo Ricarte

Harvard University

Harvard-Smithsonian Center for Astrophysics

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

National Astronomical Observatory of Japan

Tokyo Institute of Technology

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

Beijing University of Technology

Max Planck Society

Zhiqiang Shen

Chinese Academy of Sciences

Des Small

Joint Institute for VLBI in Europe (JIVE)

Bong Won Sohn

Korea Astronomy and Space Science Institute

East Asian Observatory

Yonsei University

James Clerk Maxwell Telescope

University of Science and Technology (UST)

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

Texas Tech University at Lubbock

NASA Hubble Fellowship Program

Paul Tiede

Harvard University

Harvard-Smithsonian Center for Astrophysics

Remo P. J. Tilanus

Radboud University

University of Arizona

Leiden University

Netherlands Organisation for Scientific Research (NWO)

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

Goethe University Frankfurt

University College London (UCL)

Feng Yuan

Chinese Academy of Sciences

Ye-Fei Yuan

East Asian Observatory

James Clerk Maxwell Telescope

University of Science and Technology of China

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 L17

Subject Categories

Astronomy, Astrophysics and Cosmology

Other Physics Topics

Radiology, Nuclear Medicine and Medical Imaging

DOI

10.3847/2041-8213/ac6756

More information

Latest update

5/24/2022