First Sagittarius A* Event Horizon Telescope Results. VI. Testing the Black Hole Metric
Kazunori AkiyamaA. AlberdiMassachusetts Institute of Technology Haystack Observatory, 99 Millstone Road, Westford, MA 01886, USAW. AlefInstituto de Astrofísica de Andalucía-CSIC, Glorieta de la Astronomía s/n, E-18008 Granada, SpainJuan Carlos AlgabaMax-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn, GermanyRichard AnantuaDepartment of Physics, Faculty of Science, Universiti Malaya, 50603 Kuala Lumpur, MalaysiaKeiichi AsadaCenter for Astrophysics, Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USARebecca AzulayInstitute of Astronomy and Astrophysics, Academia Sinica, 11F of Astronomy-Mathematics Building, AS/NTU No. 1, Section 4, Roosevelt Rd., Taipei 10617, Taiwan, R.O.CU. BachDepartament d'Astronomia i Astrofísica, Universitat de València, C. Dr. Moliner 50, E-46100 Burjassot, València, SpainAnne-Kathrin BaczkoMax-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn, GermanyDavid BallMax-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn, GermanyMislav BalokovićSteward Observatory and Department of Astronomy, University of Arizona, 933 N. Cherry Ave., Tucson, AZ 85721, USAJ. BarrettYale Center for Astronomy & Astrophysics, Yale University, 52 Hillhouse Avenue, New Haven, CT 06511, USAMichi BauböckMassachusetts Institute of Technology Haystack Observatory, 99 Millstone Road, Westford, MA 01886, USAB. A. BensonDepartment of Physics, University of Illinois, 1110 West Green Street, Urbana, IL 61801, USADan BintleyFermi National Accelerator Laboratory, MS209, P.O. Box 500, Batavia, IL 60510, USALindy BlackburnJames Clerk Maxwell Telescope (JCMT), 660 N. A'ohoku Place, Hilo, HI 96720, USAR. BlundellCenter for Astrophysics, Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USAKatherine L. BoumanCenter for Astrophysics, Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USAGeoffrey C. BowerCalifornia Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USAHope BoyceDepartment of Physics and Astronomy, University of Hawaii at Manoa, 2505 Correa Road, Honolulu, HI 96822, USAMichael BremerDepartment of Physics, McGill University, 3600 rue University, Montréal, QC H3A 2T8, CanadaChristiaan D. BrinkerinkInstitut de Radioastronomie Millimétrique (IRAM), 300 rue de la Piscine, F-38406 Saint Martin d'Hères, FranceRoger BrissendenDepartment of Astrophysics, Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Radboud University, P.O. Box 9010, 6500 GL Nijmegen, The NetherlandsS. BritzenBlack Hole Initiative at Harvard University, 20 Garden Street, Cambridge, MA 02138, USAAvery E. BroderickMax-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn, GermanyDominique BroguièreWaterloo Centre for Astrophysics, University of Waterloo, Waterloo, ON N2L 3G1, CanadaThomas BronzwaerInstitut de Radioastronomie Millimétrique (IRAM), 300 rue de la Piscine, F-38406 Saint Martin d'Hères, FranceSandra BustamanteDepartment of Astrophysics, Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Radboud University, P.O. Box 9010, 6500 GL Nijmegen, The NetherlandsDo‐Young ByunDepartment of Astronomy, University of Massachusetts, 01003, Amherst, MA, USAJ. E. CarlstromUniversity of Science and Technology, Gajeong-ro 217, Yuseong-gu, Daejeon 34113, Republic of KoreaChiara CeccobelloKavli Institute for Cosmological Physics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637, USAAndrew ChaelDepartment of Space, Earth and Environment, Chalmers University of Technology, Onsala Space Observatory, SE-43992 Onsala, SwedenChi‐kwan ChanPrinceton Center for Theoretical Science, Jadwin Hall, Princeton University, Princeton, NJ 08544, USAKoushik ChatterjeeProgram in Applied Mathematics, University of Arizona, 617 N. Santa Rita, Tucson, AZ 85721, USAShami ChatterjeeBlack Hole Initiative at Harvard University, 20 Garden Street, Cambridge, MA 02138, USAMing‐Tang ChenCornell Center for Astrophysics and Planetary Science, Cornell University, Ithaca, NY 14853, USAYongjun ChenXiaopeng ChengKey Laboratory of Radio Astronomy, Chinese Academy of Sciences, Nanjing 210008, People's Republic of China; Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030, People's Republic of ChinaIlje ChoKorea Astronomy and Space Science Institute, Daedeok-daero 776, Yuseong-gu, Daejeon 34055, Republic of KoreaPierre ChristianInstituto de Astrofísica de Andalucía-CSIC, Glorieta de la Astronomía s/n, E-18008 Granada, SpainNicholas S. ConroyPhysics Department, Fairfield University, 1073 North Benson Road, Fairfield, CT 06824, USAJ. E. ConwayCenter for Astrophysics, Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USAJ. M. CordesDepartment of Space, Earth and Environment, Chalmers University of Technology, Onsala Space Observatory, SE-43992 Onsala, SwedenT. M. CrawfordCornell Center for Astrophysics and Planetary Science, Cornell University, Ithaca, NY 14853, USAG. CrewKavli Institute for Cosmological Physics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637, USAAlejandro Cruz-OsorioMassachusetts Institute of Technology Haystack Observatory, 99 Millstone Road, Westford, MA 01886, USAYuzhu CuiInstitut für Theoretische Physik, Goethe-Universität Frankfurt, Max-von-Laue-Straße 1, D-60438 Frankfurt am Main, GermanyJordy DavelaarDepartment of Astronomical Science, The Graduate University for Advanced Studies (SOKENDAI), 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan; Mizusawa VLBI Observatory, National Astronomical Observatory of Japan, 2-12 Hoshigaoka, Mizusawa, Oshu, Iwate 023-0861, Japan; Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shengrong Road 520, Shanghai, 201210, People's Republic of ChinaMariafelicia De LaurentisDepartment of Astronomy and Columbia Astrophysics Laboratory, Columbia University, 550 W. 120th Street, New York, NY 10027, USARoger DeaneInstitut für Theoretische Physik, Goethe-Universität Frankfurt, Max-von-Laue-Straße 1, D-60438 Frankfurt am Main, GermanyJessica DempseyDepartment of Physics, University of Pretoria, Hatfield, Pretoria 0028, South AfricaG. DesvignesJames Clerk Maxwell Telescope (JCMT), 660 N. A'ohoku Place, Hilo, HI 96720, USAJason DexterLESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université de Paris, 5 place Jules Janssen, F-92195 Meudon, FranceVedant DhruvJILA and Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, CO 80309, USASheperd S. DoelemanDepartment of Physics, University of Illinois, 1110 West Green Street, Urbana, IL 61801, USASean DougalBlack Hole Initiative at Harvard University, 20 Garden Street, Cambridge, MA 02138, USASergio A. DzibSteward Observatory and Department of Astronomy, University of Arizona, 933 N. Cherry Ave., Tucson, AZ 85721, USARalph P. EatoughMax-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn, GermanyRazieh EmamiMax-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn, GermanyH. FalckeCenter for Astrophysics, Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USAJoseph FarahDepartment of Astrophysics, Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Radboud University, P.O. Box 9010, 6500 GL Nijmegen, The NetherlandsVincent L. FishDepartment of Physics, University of California, Santa Barbara, CA 93106-9530, USAEd FomalontMassachusetts Institute of Technology Haystack Observatory, 99 Millstone Road, Westford, MA 01886, USAH. Alyson FordNational Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903, USARaquel Fraga-EncinasSteward Observatory and Department of Astronomy, University of Arizona, 933 N. Cherry Ave., Tucson, AZ 85721, USAWilliam T. FreemanDepartment of Astrophysics, Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Radboud University, P.O. Box 9010, 6500 GL Nijmegen, The NetherlandsPer FribergDepartment of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, 32-D476, 77 Massachusetts Ave., Cambridge, MA 02142, USAChristian M. FrommJames Clerk Maxwell Telescope (JCMT), 660 N. A'ohoku Place, Hilo, HI 96720, USAAntonio FuentesInstitut für Theoretische Physik, Goethe-Universität Frankfurt, Max-von-Laue-Straße 1, D-60438 Frankfurt am Main, GermanyPeter GalisonInstituto de Astrofísica de Andalucía-CSIC, Glorieta de la Astronomía s/n, E-18008 Granada, SpainCharles F. GammieDepartment of Physics, Harvard University, Cambridge, MA 02138, USARoberto GarcíaDepartment of Physics, University of Illinois, 1110 West Green Street, Urbana, IL 61801, USAOlivier GentazInstitut de Radioastronomie Millimétrique (IRAM), 300 rue de la Piscine, F-38406 Saint Martin d'Hères, FranceBoris GeorgievInstitut de Radioastronomie Millimétrique (IRAM), 300 rue de la Piscine, F-38406 Saint Martin d'Hères, FranceC. GoddiPerimeter Institute for Theoretical Physics, 31 Caroline Street N, Waterloo, ON N2L 2Y5, CanadaRoman GoldINAF—Osservatorio Astronomico di Cagliari, Via della Scienza 5, I-09047, Selargius, CA, ItalyArturo I. Gómez-RuizInstitut für Theoretische Physik, Goethe-Universität Frankfurt, Max-von-Laue-Straße 1, D-60438 Frankfurt am Main, GermanyJosé L. GómezInstituto Nacional de Astrofísica, Óptica y Electrónica. Apartado Postal 51 y 216, 72000. Puebla Pue., MéxicoMinfeng GuInstituto de Astrofísica de Andalucía-CSIC, Glorieta de la Astronomía s/n, E-18008 Granada, SpainMark GurwellKey Laboratory for Research in Galaxies and Cosmology, Chinese Academy of Sciences, Shanghai 200030, People's Republic of China; Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030, People's Republic of ChinaKazuhiro HadaCenter for Astrophysics, Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USADaryl HaggardMizusawa VLBI Observatory, National Astronomical Observatory of Japan, 2-12 Hoshigaoka, Mizusawa, Oshu, Iwate 023-0861, JapanKari HaworthMcGill Space Institute, McGill University, 3550 rue University, Montréal, QC H3A 2A7, CanadaM. H. HechtCenter for Astrophysics, Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USARonald HesperMassachusetts Institute of Technology Haystack Observatory, 99 Millstone Road, Westford, MA 01886, USADirk HeumannNOVA Sub-mm Instrumentation Group, Kapteyn Astronomical Institute, University of Groningen, Landleven 12, 9747 AD Groningen, The NetherlandsLuis C. HoSteward Observatory and Department of Astronomy, University of Arizona, 933 N. Cherry Ave., Tucson, AZ 85721, USAPaul T. P. HoDepartment of Astronomy, School of Physics, Peking University, Beijing 100871, People's Republic of China; Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871, People's Republic of ChinaMareki HonmaJames Clerk Maxwell Telescope (JCMT), 660 N. A'ohoku Place, Hilo, HI 96720, USAChih-Wei L. HuangMizusawa VLBI Observatory, National Astronomical Observatory of Japan, 2-12 Hoshigaoka, Mizusawa, Oshu, Iwate 023-0861, JapanLei 磊 Huang 黄Institute of Astronomy and Astrophysics, Academia Sinica, 11F of Astronomy-Mathematics Building, AS/NTU No. 1, Section 4, Roosevelt Rd., Taipei 10617, Taiwan, R.O.CD. H. HughesKey Laboratory for Research in Galaxies and Cosmology, Chinese Academy of Sciences, Shanghai 200030, People's Republic of China; Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030, People's Republic of ChinaShiro IkedaInstituto Nacional de Astrofísica, Óptica y Electrónica. Apartado Postal 51 y 216, 72000. Puebla Pue., MéxicoC. M. Violette ImpellizzeriDepartment of Statistical Science, The Graduate University for Advanced Studies (SOKENDAI), 10-3 Midori-cho, Tachikawa, Tokyo 190-8562, JapanMakoto InoueLeiden Observatory, Leiden University, Postbus 2300, 9513 RA Leiden, The NetherlandsSara IssaounInstitute of Astronomy and Astrophysics, Academia Sinica, 11F of Astronomy-Mathematics Building, AS/NTU No. 1, Section 4, Roosevelt Rd., Taipei 10617, Taiwan, R.O.CD. J. JamesCenter for Astrophysics, Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USABuell T. JannuziASTRAVEO LLC, P.O. Box 1668, Gloucester, MA 01931, USAMichaël JanssenSteward Observatory and Department of Astronomy, University of Arizona, 933 N. Cherry Ave., Tucson, AZ 85721, USABritton JeterMax-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn, Germany
2022en
ABI
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.
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