First Sagittarius A* Event Horizon Telescope Results. II. EHT and Multiwavelength Observations, Data Processing, and Calibration
Journal article, 2022
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 similar to 50 mu 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.
Author
Kazunori Akiyama
National Astronomical Observatory of Japan
Massachusetts Institute of Technology (MIT)
Harvard University
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 University
Harvard-Smithsonian Center for Astrophysics
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
The Graduate University for Advanced Studies (SOKENDAI)
National Astronomical Observatory of Japan
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 Pretoria
University of Witwatersrand
Rhodes University
Jessica Dempsey
East Asian Observatory
James Clerk Maxwell Telescope
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 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
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
Istituto nazionale di astrofisica (INAF)
University of Cagliari
Roman Gold
University of Southern Denmark
Goethe University Frankfurt
Gomez-Ruiz
National Council for Science and Technology Mexico
National Institute of Astrophysics, Optics and Electronics
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
East Asian Observatory
James Clerk Maxwell Telescope
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 Institute of Statistical Mathematics
University of Tokyo
The Graduate University for Advanced Studies (SOKENDAI)
National Astronomical Observatory of Japan
C. M. Violette Impellizzeri
National Radio Astronomy Observatory
Leiden University
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
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
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 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
East Asian Observatory
James Clerk Maxwell Telescope
Yosuke Mizuno
Goethe University Frankfurt
Shanghai Jiao Tong University
James M. Moran
Harvard-Smithsonian Center for Astrophysics
Harvard University
Kotaro Moriyama
Massachusetts Institute of Technology (MIT)
Goethe University Frankfurt
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
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-Smithsonian Center for Astrophysics
Harvard University
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)
Joseph 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
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
Perimeter Institute for Theoretical Physics
University of Toronto
Academia Sinica
Canadian Institute for Advanced Research
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
Hung-Yi Pu
National Taiwan Normal University
Academia Sinica
Venkatessh Ramakrishnan
Aalto University
University of Turku
University of Concepcion
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
Frankfurt Institute for Advanced Studies
Goethe University Frankfurt
Angelo Ricarte
Harvard University
Harvard-Smithsonian Center for Astrophysics
Bart Ripperda
Princeton University
Flatiron Institute
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
Istituto nazionale di astrofisica (INAF)
Italian ALMA Regional Centre
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
Hiroshima University
Tokyo Institute of Technology
National Astronomical Observatory of Japan
Kaushik Satapathy
University of Arizona
Tuomas Savolainen
Aalto University
Max Planck Society
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
University of Science and Technology (UST)
Yonsei University
Korea Astronomy and Space Science Institute
James Clerk Maxwell Telescope
East Asian Observatory
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
Leiden University
University of Arizona
Radboud University
Netherlands Organisation for Scientific Research (NWO)
Michael Titus
Massachusetts Institute of Technology (MIT)
Pablo Torne
Max Planck Society
Institut de Radioastronomie Millimétrique (IRAM)
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)
University of New Mexico
Leiden University
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
Princeton University
Institute for Advanced Study
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
University of Science and Technology of China
James Clerk Maxwell Telescope
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
Claudio Agurto
European Southern Observatory Santiago
Juan Pablo Araneda
European Southern Observatory Santiago
Oriel Arriagada
European Southern Observatory Santiago
Alessandra Bertarini
University of Bonn
Max Planck Society
Ryan Berthold
James Clerk Maxwell Telescope
East Asian Observatory
Jay Blanchard
National Radio Astronomy Observatory
Ken Brown
James Clerk Maxwell Telescope
East Asian Observatory
Mauricio Cardenas
European Southern Observatory Santiago
Michael Cantzler
European Southern Observatory Santiago
Patricio Caro
European Southern Observatory Santiago
Tim C. Chuter
James Clerk Maxwell Telescope
East Asian Observatory
Miroslaw Ciechanowicz
Max Planck Society
European Southern Observatory Santiago
Iain M. Coulson
James Clerk Maxwell Telescope
East Asian Observatory
Joseph Crowley
Massachusetts Institute of Technology (MIT)
Nathalie Degenaar
University of Amsterdam
Sven Dornbusch
Max Planck Society
Carlos A. Duran
European Southern Observatory Santiago
Karl Forster
California Institute of Technology (Caltech)
Gertie Geertsema
Royal Netherlands Meteorological Institute
Edouard Gonzalez
European Southern Observatory Santiago
Dave Graham
Max Planck Society
Frederic Gueth
Institut de Radioastronomie Millimétrique (IRAM)
Chih-Chiang Han
Academia Sinica
Cristian Herrera
European Southern Observatory Santiago
Ruben Herrero-Illana
European Southern Observatory Santiago
Stefan Heyminck
Max Planck Society
James Hoge
East Asian Observatory
James Clerk Maxwell Telescope
Yau-De Huang
Academia Sinica
Homin Jiang
Academia Sinica
David John
Institut de Radioastronomie Millimétrique (IRAM)
Thomas Klein
European Southern Observatory Santiago
Derek Kubo
Academia Sinica
John Kuroda
East Asian Observatory
James Clerk Maxwell Telescope
Caleb Kwon
Villanova University
Robert Laing
Square Kilometre Array, UK
European Southern Observatory Santiago
Ching-Tang Liu
Academia Sinica
Kuan-Yu Liu
James Clerk Maxwell Telescope
Academia Sinica
East Asian Observatory
Felipe Mac-Auliffe
European Southern Observatory Santiago
Pierre Martin-Cocher
Academia Sinica
Callie Matulonis
James Clerk Maxwell Telescope
East Asian Observatory
Hugo Messias
European Southern Observatory Santiago
Atacama Large Millimeter-submillimeter Array (ALMA)
Zheng Meyer-Zhao
Netherlands Institute for Radio Astronomy (ASTRON)
Francisco Montenegro-Montes
European Southern Observatory Santiago
William Montgomerie
James Clerk Maxwell Telescope
East Asian Observatory
National Aeronautics and Space Administration (NASA)
Dirk Muders
Max Planck Society
Hiroaki Nishioka
Academia Sinica
Timothy J. Norton
Harvard-Smithsonian Center for Astrophysics
Rodrigo Olivares
European Southern Observatory Santiago
Juan Pablo Perez-Beaupuits
Pontificia Universidad Catolica de Chile
European Southern Observatory Santiago
Max Planck Society
Rodrigo Parra
European Southern Observatory Santiago
Michael Poirier
Massachusetts Institute of Technology (MIT)
Nicolas Pradel
Academia Sinica
Philippe A. Raffin
Academia Sinica
Jorge Ramirez
European Southern Observatory Santiago
Mark Reynolds
University of Michigan
Alejandro F. Saez-Madain
National Radio Astronomy Observatory
Atacama Large Millimeter-submillimeter Array (ALMA)
Jorge Santana
European Southern Observatory Santiago
Kevin M. Silva
East Asian Observatory
James Clerk Maxwell Telescope
Don Sousa
Massachusetts Institute of Technology (MIT)
William Stahm
James Clerk Maxwell Telescope
East Asian Observatory
Karl Torstensson
European Southern Observatory Santiago
Paulina Venegas
European Southern Observatory Santiago
Craig Walther
James Clerk Maxwell Telescope
East Asian Observatory
Gundolf Wieching
Max Planck Society
Rudy Wijnands
University of Amsterdam
Jan G. A. Wouterloot
James Clerk Maxwell Telescope
East Asian Observatory
Astrophysical Journal Letters
2041-8205 (ISSN) 2041-8213 (eISSN)
Vol. 930 2 L13Subject Categories (SSIF 2011)
Accelerator Physics and Instrumentation
Meteorology and Atmospheric Sciences
Astronomy, Astrophysics and Cosmology
DOI
10.3847/2041-8213/ac6675