First Sagittarius A* Event Horizon Telescope Results. II. EHT and Multiwavelength Observations, Data Processing, and Calibration
Kazunori AkiyamaA. AlberdiNational Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, JapanW. 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 AsadaBlack Hole Initiative at Harvard University, 20 Garden Street, Cambridge, MA 02138, USARebecca AzulayInstitute of Astronomy and Astrophysics, Academia Sinica, 11F of Astronomy-Mathematics Building, AS/NTU No. 1, Sec. 4, Roosevelt Rd., Taipei 10617, Taiwan, R.O.CU. BachMax-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn, GermanyAnne-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 BintleyDepartment of Astronomy and Astrophysics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637, 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 BroguièreDepartment of Physics and Astronomy, University of Waterloo, 200 University Avenue W, 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, Amherst, MA 01003, USAJ. E. CarlstromKorea Astronomy and Space Science Institute, Daedeok-daero 776, Yuseong-gu, Daejeon 34055, Republic Of KoreaChiara CeccobelloEnrico Fermi Institute, 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 ChanNASA Hubble Fellowship Program, Einstein FellowKoushik ChatterjeeSteward Observatory and Department of Astronomy, University of Arizona, 933 N. Cherry Ave., Tucson, AZ 85721, USAShami ChatterjeeCenter for Astrophysics ∣ Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USAMing‐Tang ChenCornell Center for Astrophysics and Planetary Science, Cornell University, Ithaca, NY 14853, USAYongjun ChenXiaopeng ChengIlje 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. CrewDepartment of Astronomy and Astrophysics, 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 DavelaarMariafelicia De LaurentisCenter for Computational Astrophysics, Flatiron Institute, 162 Fifth Avenue, New York, NY 10010, USARoger DeaneINFN Sez. di Napoli, Compl. Univ. di Monte S. Angelo, Edificio G, Via Cinthia, I-80126, Napoli, ItalyJessica DempseyDepartment of Physics, University of Pretoria, Hatfield, Pretoria 0028, South AfricaG. DesvignesASTRON, Oude Hoogeveensedijk 4, 7991 PD Dwingeloo, The NetherlandsJason 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 EmamiNational Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing 100101, People's Republic of ChinaH. 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 FuentesMax-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn, GermanyPeter GalisonInstituto de Astrofísica de Andalucía-CSIC, Glorieta de la Astronomía s/n, E-18008 Granada, SpainCharles F. GammieDepartment of History of Science, Harvard University, Cambridge, MA 02138, USARoberto GarcíaDepartment of Astronomy, University of Illinois at Urbana-Champaign, 1002 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. GoddiWaterloo Centre for Astrophysics, University of Waterloo, Waterloo, ON N2L 3G1, CanadaRoman GoldDipartimento di Fisica, Università degli Studi di Cagliari, SP Monserrato-Sestu km 0.7, I-09042 Monserrato, ItalyArturo I. Gómez-RuizCP3-Origins, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, DenmarkJosé L. GómezConsejo Nacional de Ciencia y Tecnologìa, Av. Insurgentes Sur 1582, 03940, Ciudad de México, MéxicoMinfeng GuInstituto de Astrofísica de Andalucía-CSIC, Glorieta de la Astronomía s/n, E-18008 Granada, SpainMark GurwellKazuhiro HadaCenter for Astrophysics ∣ Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USADaryl HaggardDepartment of Astronomical Science, The Graduate University for Advanced Studies (SOKENDAI), 2-21-1 Osawa, Mitaka, Tokyo 181-8588, 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. HoMareki HonmaJames Clerk Maxwell Telescope (JCMT), 660 N. A'ohoku Place, Hilo, HI 96720, USAChih-Wei L. HuangDepartment of Astronomy, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, JapanLei 磊 Huang 黄Institute of Astronomy and Astrophysics, Academia Sinica, 11F of Astronomy-Mathematics Building, AS/NTU No. 1, Sec. 4, Roosevelt Rd., Taipei 10617, Taiwan, R.O.CD. H. HughesShiro IkedaInstituto Nacional de Astrofísica, Óptica y Electrónica. Apartado Postal 51 y 216, 72000. Puebla Pue., MéxicoC. M. Violette ImpellizzeriNational Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, JapanMakoto InoueNational Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903, USASara IssaounInstitute of Astronomy and Astrophysics, Academia Sinica, 11F of Astronomy-Mathematics Building, AS/NTU No. 1, Sec. 4, Roosevelt Rd., Taipei 10617, Taiwan, R.O.CD. J. JamesNASA Hubble Fellowship Program, Einstein FellowBuell T. JannuziASTRAVEO LLC, PO 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
Аннотация
Abstract We present Event Horizon Telescope (EHT) 1.3 mm measurements of the radio source located at the position of the supermassive black hole Sagittarius A* (Sgr A*), collected during the 2017 April 5–11 campaign. The observations were carried out with eight facilities at six locations across the globe. Novel calibration methods are employed to account for Sgr A*'s flux variability. The majority of the 1.3 mm emission arises from horizon scales, where intrinsic structural source variability is detected on timescales of minutes to hours. The effects of interstellar scattering on the image and its variability are found to be subdominant to intrinsic source structure. The calibrated visibility amplitudes, particularly the locations of the visibility minima, are broadly consistent with a blurred ring with a diameter of ∼50 μ as, as determined in later works in this series. Contemporaneous multiwavelength monitoring of Sgr A* was performed at 22, 43, and 86 GHz and at near-infrared and X-ray wavelengths. Several X-ray flares from Sgr A* are detected by Chandra, one at low significance jointly with Swift on 2017 April 7 and the other at higher significance jointly with NuSTAR on 2017 April 11. The brighter April 11 flare is not observed simultaneously by the EHT but is followed by a significant increase in millimeter flux variability immediately after the X-ray outburst, indicating a likely connection in the emission physics near the event horizon. We compare Sgr A*’s broadband flux during the EHT campaign to its historical spectral energy distribution and find that both the quiescent emission and flare emission are consistent with its long-term behavior.
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