Horizon-scale variability of M87* from 2017–2021 EHT observations
Journal article, 2025
We report three epochs of polarized images of M87* at 230 GHz using data from the Event Horizon Telescope (EHT) taken in 2017, 2018, and 2021. The baseline coverage of the 2021 observations is significantly improved through the addition of two new EHT stations: the 12 m Kitt Peak Telescope and the Northern Extended Millimetre Array (NOEMA). All observations result in images dominated by a bright, asymmetric ring with a persistent diameter of 43.9 ± 0.6 µas, consistent with expectations for lensed synchrotron emission encircling the apparent shadow of a supermassive black hole. We find that the total intensity and linear polarization of M87* vary significantly across the three epochs. Specifically, the azimuthal brightness distribution of the total intensity images varies from year to year, as expected for a stochastic accretion flow. However, despite a gamma-ray flare erupting in M87 quasi-contemporaneously to the 2018 observations, the 2018 and 2021 images look remarkably similar. The resolved linear polarization fractions in 2018 and 2021 peak at ∼5%, compared to ∼15% in 2017. The spiral polarization pattern on the ring also varies from year to year, including a change in the electric vector position angle helicity in 2021 that could reflect changes in the magnetized accretion flow or an external Faraday screen. The improved 2021 coverage also provides the first EHT constraints on jet emission outside the ring, on scales of .1 mas. Overall, these observations provide strong proof of the reliability of the EHT images and probe the dynamic properties of the horizon-scale accretion flow surrounding M87*.
black hole physics
accretion, accretion disks
galaxies: jets
galaxies: individual: M87*
gravitation
galaxies: active
Author
Kazunori Akiyama
National Astronomical Observatory of Japan
Massachusetts Institute of Technology (MIT)
Harvard University
E. Albentosa-Ruiz
Universitat de Valencia
Antxon Alberdi
Spanish National Research Council (CSIC)
Walter Alef
Max Planck Society
Juan-Carlos Algaba
University of Malaya
Richard Anantua
Rice University
Harvard-Smithsonian Center for Astrophysics
University of Texas
Harvard University
K. Asada
Academia Sinica
R. Azulay
Universitat de Valencia
Max Planck Society
U. Bach
Max Planck Society
Anne-Kathrin Baczko
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
Max Planck Society
David Ball
University of Arizona
Mislav Baloković
Yale University
Bidisha Bandyopadhyay
University of Concepcion
John Barrett
Massachusetts Institute of Technology (MIT)
M. Bauböck
Grainger College of Engineering
Bradford A. Benson
University of Chicago
Fermi National Accelerator Laboratory
Dan Bintley
James Clerk Maxwell Telescope
East Asian Observatory
Lindy Blackburn
Harvard-Smithsonian Center for Astrophysics
Harvard University
R. Blundell
Harvard-Smithsonian Center for Astrophysics
K. L. Bouman
California Institute of Technology (Caltech)
G. C. Bower
James Clerk Maxwell Telescope
Academia Sinica
East Asian Observatory
University of Hawaii
M. Bremer
Institut de Radioastronomie Millimétrique (IRAM)
Roger Brissenden
Harvard-Smithsonian Center for Astrophysics
Silke Britzen
Max Planck Society
Avery E. Broderick
Perimeter Institute for Theoretical Physics
University of Waterloo
D. Broguière
Institut de Radioastronomie Millimétrique (IRAM)
Thomas Bronzwaer
Radboud University
Sandra Bustamente
University of Massachusetts
Douglas Ferreira Carlos
University of Sao Paulo (USP)
J. E. Carlstrom
The Enrico Fermi Institute
University of Chicago
A. Chael
Princeton University
Chi Kwan Chan
University of Arizona
Dominic O. Chang
Harvard-Smithsonian Center for Astrophysics
Harvard University
Erandi Chavez
Harvard-Smithsonian Center for Astrophysics
Koushik Chatterjee
University of Maryland
Harvard University
Harvard-Smithsonian Center for Astrophysics
S. Chatterjee
Cornell University
Ming Tang Chen
Academia Sinica
Yongjun Chen
Chinese Academy of Sciences
X. P. Cheng
Korea Astronomy and Space Science Institute
Paul Chichura
University of Chicago
I. Cho
Yonsei University
Spanish National Research Council (CSIC)
Korea Astronomy and Space Science Institute
Pierre Christian
WattTime
Nicholas S. Conroy
University of Illinois
Harvard-Smithsonian Center for Astrophysics
John Conway
Chalmers, Space, Earth and Environment, Onsala Space Observatory
Thomas M. Crawford
University of Chicago
G. Crew
Massachusetts Institute of Technology (MIT)
Alejandro Cruz-Osorio
Universidad Nacional Autónoma de México
Goethe University Frankfurt
Yuzhu Cui
Huazhong Normal University
Brandon Curd
Harvard University
Harvard-Smithsonian Center for Astrophysics
University of Texas
Rohan Dahale
Spanish National Research Council (CSIC)
Jordy Davelaar
National Aeronautics and Space Administration (NASA)
Princeton University
Mariafelicia De Laurentis
National Institute for Nuclear Physics
University of Naples Federico II
R. P. Deane
Rhodes University
University of Pretoria
University of Witwatersrand
Gregory Desvignes
JILA
Paris Observatory
Max Planck Society
Jason Dexter
Paris Observatory
Vedant Dhruv
Grainger College of Engineering
Indu K. Dihingia
Shanghai Jiao Tong University
S. Doeleman
Harvard-Smithsonian Center for Astrophysics
Harvard University
Sergio A. Dzib
Max Planck Society
Ralph P. Eatough
Chinese Academy of Sciences
Max Planck Society
Razieh Emami
Harvard-Smithsonian Center for Astrophysics
H.D. Falcke
Radboud University
Joseph R. Farah
Las Cumbres Observatory Global Telescope Network
University of California
V. Fish
Massachusetts Institute of Technology (MIT)
E. Fomalont
National Radio Astronomy Observatory
H.D. Falcke
University of Arizona
Marianna Foschi
Spanish National Research Council (CSIC)
R. Fraga-Encinas
Radboud University
William T. Freeman
Google Inc.
Massachusetts Institute of Technology (MIT)
P. Friberg
East Asian Observatory
James Clerk Maxwell Telescope
Christian M. Fromm
Max Planck Society
University of Würzburg
Goethe University Frankfurt
Antonio Fuentes
Spanish National Research Council (CSIC)
Peter Galison
Harvard University
Charles F. Gammie
Grainger College of Engineering
University of Illinois
Roberto Garcia
Institut de Radioastronomie Millimétrique (IRAM)
Olivier Gentaz
Institut de Radioastronomie Millimétrique (IRAM)
Boris Georgiev
University of Arizona
C. Goddi
University of Cagliari
National Institute for Nuclear Physics
Istituto nazionale di astrofisica (INAF)
University of Sao Paulo (USP)
R. Gold
Heidelberg University
University of Southern Denmark
Arturo I. Gómez-Ruiz
National Council for Science and Technology Mexico
National Institute of Astrophysics, Optics and Electronics
José L. Gómez
Spanish National Research Council (CSIC)
Minfeng Gu
Chinese Academy of Sciences
M. Gurwell
Harvard-Smithsonian Center for Astrophysics
K. Hada
National Astronomical Observatory of Japan
University of Tokyo
Daryl Haggard
McGill University
R. Hesper
University of Groningen
Dirk Heumann
University of Arizona
Luis C. Ho
Beijing University of Technology
P. T. P. Ho
Academia Sinica
James Clerk Maxwell Telescope
East Asian Observatory
Dan Hoak
Massachusetts Institute of Technology (MIT)
Mareki Honma
National Astronomical Observatory of Japan
The Graduate University for Advanced Studies (SOKENDAI)
University of Tokyo
Chih Wei L. Huang
Academia Sinica
Lei Huang
Chinese Academy of Sciences
D. Hughes
National Institute of Astrophysics, Optics and Electronics
Shiro Ikeda
The Graduate University for Advanced Studies (SOKENDAI)
University of Tokyo
National Astronomical Observatory of Japan
The Institute of Statistical Mathematics
C. M. V. Impellizzeri
National Radio Astronomy Observatory
Leiden University
Makoto Inoue
Academia Sinica
S. Issaoun
Harvard-Smithsonian Center for Astrophysics
David J. James
Applied Materials Incorporated
ASTRAVEO
Buell T. Jannuzi
University of Arizona
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 704 A91RadioNet 4
European Commission (EC) (EC/H2020/730562), 2017-01-01 -- 2020-12-31.
Onsala space observatory infrastructure
Swedish Research Council (VR) (2017-00648), 2018-01-01 -- 2021-12-31.
RADIOBLOCKS New science in Radio Astronomy: applying cutting-edge technology to enhance the entire data chain, from receiver to final output
European Commission (EC) (EC/HE/101093934), 2023-03-01 -- 2027-02-28.
Subject Categories (SSIF 2025)
Computer graphics and computer vision
Astronomy, Astrophysics, and Cosmology
Meteorology and Atmospheric Sciences
DOI
10.1051/0004-6361/202555855