Full-polarization millimeter wavelength variability of Sagittarius A* during the 2018 EHT campaign
Artikel i vetenskaplig tidskrift, 2026
Context. Sagittarius A* (Sgr A*), the supermassive black hole at the center of the Milky Way, provides a unique laboratory to study accretion dynamics and plasma processes near the event horizon. Aims. We investigated the variability and polarization properties of Sgr A* using ALMA observations during the 2018 Event Horizon Telescope campaign. Methods. We analyzed high-cadence full-polarization light curves from ALMA at millimeter wavelengths, performed time-series analysis, and investigated the temporal behavior during an X-ray flare observed by Chandra on 2018 April 24. The variability characteristics are compared with expectations from standard accretion flow models. Results. We find low variability in total intensity (sigma/mu < 10%), but significantly higher variability in linear and circular polarization ( similar to 30% and similar to 50%, respectively). A time-series analysis reveals red-noise variability, with power spectral densities between 2 and 3 across all Stokes parameters. Polarized intensity shows stable intra-day timescales, while total intensity exhibits more variable timescales, suggesting distinct emission regions, with polarization likely arising from a coherent structure. On April 24, a statistically significant inter-band delay in polarized intensity coincides with a near-simultaneous X-ray and millimeter peak that deviates from the typical delayed flare scenario. This event also features enhanced millimeter variability and coherent polarization loop evolution. The observed simultaneity challenges standard models of transient synchrotron emission with cooling delays, favoring instead a scenario of continuous energy injection in an optically thin region. Conclusions. Our results offer new constraints on the physical mechanisms driving variability in Sgr A*, and provide key observational input for refining theoretical models of accretion and plasma behavior in the vicinity of supermassive black holes.
techniques: interferometric
Galaxy: center
techniques: polarimetric
black hole physics
Författare
Ezequiel Albentosa-Ruiz
Universitat de Valencia
Jasmin E. Washington
University of Arizona
Nicola Marchili
Istituto nazionale di astrofisica (INAF)
Max-Planck-Gesellschaft
Italian ALMA Regional Centre
Ivan Marti-Vidal
Universitat de Valencia
Ciriaco Goddi
Universidade de Sao Paulo (USP)
Istituto Nazionale di Fisica Nucleare
Istituto nazionale di astrofisica (INAF)
Universita degli Studi di Cagliari
Maciek Wielgus
Consejo Superior de Investigaciones Científicas (CSIC)
Alejandro Mus
Italian ALMA Regional Centre
Universita degli Studi di Cagliari
Istituto nazionale di astrofisica (INAF)
Angelo Ricarte
Harvard University
Harvard-Smithsonian Center for Astrophysics
Daniel P. Marrone
University of Arizona
Leon D. S. Salas
Universiteit Van Amsterdam
Yuhei Iwata
National Astronomical Observatory of Japan
Douglas F. Carlos
Universidade de Sao Paulo (USP)
Alexandra J. Tetarenko
University of Lethbridge
Kotaro Moriyama
Johann Wolfgang Goethe Universität Frankfurt am Main
National Astronomical Observatory of Japan
Vedant Dhruv
University of Illinois
Kazunori Akiyama
National Astronomical Observatory of Japan
Massachusetts Institute of Technology (MIT)
Harvard University
Antxon Alberdi
Consejo Superior de Investigaciones Científicas (CSIC)
Walter Alef
Max-Planck-Gesellschaft
Juan Carlos Algaba
University of Malaya
Richard Anantua
Harvard University
Rice University
Harvard-Smithsonian Center for Astrophysics
University of Texas
Keiichi Asada
Academia Sinica
Rebecca Azulay
Max-Planck-Gesellschaft
Universitat de Valencia
Uwe Bach
Max-Planck-Gesellschaft
David Ball
University of Arizona
Mislav Balokovic
Yale University
Bidisha Bandyopadhyay
Universidad de Concepción
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
James Clerk Maxwell Telescope
Academia Sinica
East Asian Observatory
University of Hawaii
Michael Bremer
Institut de Radioastronomie Millimétrique (IRAM)
Roger Brissenden
Harvard University
Harvard-Smithsonian Center for Astrophysics
Silke Britzen
Max-Planck-Gesellschaft
Avery E. Broderick
University of Waterloo
Perimeter Institute for Theoretical Physics
Dominique Broguiere
Institut de Radioastronomie Millimétrique (IRAM)
Thomas Bronzwaer
Radboud Universiteit
Sandra Bustamante
University of Massachusetts
John E. Carlstrom
University of Chicago
Andrew Chael
Princeton University
Chi-kwan Chan
University of Arizona
Dominic O. Chang
Harvard-Smithsonian Center for Astrophysics
Harvard University
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
Pierre Christian
WattTime
Ilje Cho
Consejo Superior de Investigaciones Científicas (CSIC)
Korea Astronomy and Space Science Institute
Yonsei University
Nicholas S. Conroy
Harvard-Smithsonian Center for Astrophysics
University of Illinois
Thomas M. Crawford
University of Chicago
Geoffrey B. Crew
Massachusetts Institute of Technology (MIT)
Alejandro Cruz-Osorio
Universidad Nacional Autónoma de México
Johann Wolfgang Goethe Universität Frankfurt am Main
Yuzhu Cui
Central China Normal University
Brandon Curd
University of Texas
Harvard University
Harvard-Smithsonian Center for Astrophysics
Rohan Dahale
Consejo Superior de Investigaciones Científicas (CSIC)
Jordy Davelaar
National Aeronautics and Space Administration (NASA)
Princeton University
Mariafelicia De laurentis
Universita degli Studi di Napoli Federico II
Istituto Nazionale di Fisica Nucleare
Roger Deane
Rhodes University
University of Witwatersrand
Universiteit van Pretoria
Jessica Dempsey
James Clerk Maxwell Telescope
Netherlands Institute for Radio Astronomy (ASTRON)
East Asian Observatory
Gregory Desvignes
Université Paris Descartes
Max-Planck-Gesellschaft
Jason Dexter
University of Colorado
Indu K. Dihingia
Shanghai Jiao Tong University
Sheperd S. Doeleman
Harvard University
Harvard-Smithsonian Center for Astrophysics
Sergio A. Dzib
Max-Planck-Gesellschaft
Ralph P. Eatough
Chinese Academy of Sciences
Max-Planck-Gesellschaft
Razieh Emami
Harvard-Smithsonian Center for Astrophysics
Heino Falcke
Radboud Universiteit
Joseph Farah
Las Cumbres Observatory Global Telescope Network
University of California
Vincent L. Fish
Massachusetts Institute of Technology (MIT)
Edward Fomalont
National Radio Astronomy Observatory
H. Alyson Ford
University of Arizona
Marianna Foschi
Consejo Superior de Investigaciones Científicas (CSIC)
Antonio Fuentes
Consejo Superior de Investigaciones Científicas (CSIC)
Raquel Fraga-Encinas
Radboud Universiteit
William T. Freeman
Google Inc.
Massachusetts Institute of Technology (MIT)
Per Friberg
James Clerk Maxwell Telescope
East Asian Observatory
Christian M. Fromm
Max-Planck-Gesellschaft
Julius-Maximilians Universität Würzburg
Johann Wolfgang Goethe Universität Frankfurt am Main
Peter Galison
Harvard University
Charles F. Gammie
University of Illinois
Roberto Garcia
Institut de Radioastronomie Millimétrique (IRAM)
Olivier Gentaz
Institut de Radioastronomie Millimétrique (IRAM)
Gertie Geertsema
Royal Netherlands Meteorological Institute
Boris Georgiev
University of Arizona
Roman Gold
Universität Heidelberg
Syddansk Universitet
Jose L. Gomez
Consejo Superior de Investigaciones Científicas (CSIC)
Arturo I. Gomez-Ruiz
Consejo Nacional de Ciencia y Tecnologia Mexico
Instituto Nacional de Astrofísica, Óptica y Electrońica
Minfeng Gu
Chinese Academy of Sciences
Mark Gurwell
Harvard-Smithsonian Center for Astrophysics
Kazuhiro Hada
Nagoya City University
National Astronomical Observatory of Japan
Daryl Haggard
McGill University
Ronald Hesper
Rijksuniversiteit Groningen
Dirk Heumann
University of Arizona
Luis C. Ho
Beijing University of Technology
Paul Ho
East Asian Observatory
Academia Sinica
James Clerk Maxwell Telescope
Mareki Honma
The Graduate University for Advanced Studies (SOKENDAI)
University of Tokyo
National Astronomical Observatory of Japan
Chih-Wei L. Huang
Academia Sinica
Lei Huang
Chinese Academy of Sciences
David H. Hughes
Instituto Nacional de Astrofísica, Óptica y Electrońica
Shiro Ikeda
The Institute of Statistical Mathematics
National Astronomical Observatory of Japan
University of Tokyo
The Graduate University for Advanced Studies (SOKENDAI)
C. M. Violette Impellizzeri
National Radio Astronomy Observatory
Universiteit Leiden
Makoto Inoue
Academia Sinica
Sara Issaoun
National Aeronautics and Space Administration (NASA)
Harvard-Smithsonian Center for Astrophysics
David J. James
ASTRAVEO
Applied Materials Incorporated
Buell T. Jannuzi
University of Arizona
Michael Janssen
Radboud Universiteit
Max-Planck-Gesellschaft
Britton Jeter
Academia Sinica
Wu Jiang
Chinese Academy of Sciences
Alejandra Jimenez-Rosales
Radboud Universiteit
Michael D. Johnson
Harvard-Smithsonian Center for Astrophysics
Harvard University
Adam C. Jones
University of Chicago
Svetlana Jorstad
Boston University
Abhishek V. Joshi
University of Arizona
University of Illinois
Taehyun Jung
University of Science and Technology (UST)
Korea Astronomy and Space Science Institute
Ramesh Karuppusamy
Max-Planck-Gesellschaft
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
Commonwealth Scientific and Industrial Research Organisation (CSIRO)
Jae-Young Kim
Max-Planck-Gesellschaft
Ulsan National Institute of Science and Technology (UNIST)
Jongsoo Kim
Korea Astronomy and Space Science Institute
Junhan Kim
Korea Advanced Institute of Science and Technology (KAIST)
Motoki Kino
Kogakuin University of Technology and Engineering
National Astronomical Observatory of Japan
Jun Yi Koay
Academia Sinica
Prashant Kocherlakota
Johann Wolfgang Goethe Universität Frankfurt am Main
Yutaro Kofuji
University of Tokyo
National Astronomical Observatory of Japan
Patrick M. Koch
Academia Sinica
Shoko Koyama
Academia Sinica
Niigata University
Carsten Kramer
Institut de Radioastronomie Millimétrique (IRAM)
Joana A. Kramer
Max-Planck-Gesellschaft
Michael Kramer
Max-Planck-Gesellschaft
Thomas P. Krichbaum
Max-Planck-Gesellschaft
Cheng-Yu Kuo
Academia Sinica
National Sun Yat-Sen University
Noemi La Bella
Radboud Universiteit
Sang-Sung Lee
Korea Astronomy and Space Science Institute
Aviad Levis
California Institute of Technology (Caltech)
Zhiyuan Li
Nanjing University
Rocco Lico
Italian ALMA Regional Centre
Consejo Superior de Investigaciones Científicas (CSIC)
Istituto nazionale di astrofisica (INAF)
Greg Lindahl
Common Crawl Foundation
Michael Lindqvist
Mikhail Lisakov
Pontificia Universidad Católica de Valparaíso
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Max-Planck-Gesellschaft
Kuo Liu
Chinese Academy of Sciences
Elisabetta Liuzzo
Italian ALMA Regional Centre
Istituto nazionale di astrofisica (INAF)
Wen-Ping Lo
National Taiwan University
Academia Sinica
Andrei P. Lobanov
Max-Planck-Gesellschaft
Laurent Loinard
Harvard University
Universidad Nacional Autónoma de México
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Massachusetts Institute of Technology (MIT)
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University of Arizona
Ru-Sen Lu
Chinese Academy of Sciences
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Chinese Academy of Sciences
Sera Marko
Universiteit Van Amsterdam
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Boston University
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Massachusetts Institute of Technology (MIT)
Lia Medeiros
National Aeronautics and Space Administration (NASA)
Princeton University
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Max-Planck-Gesellschaft
Izumi Mizuno
East Asian Observatory
James Clerk Maxwell Telescope
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Johann Wolfgang Goethe Universität Frankfurt am Main
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McGill University
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Harvard University
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Monika Moscibrodzka
Radboud Universiteit
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Max-Planck-Gesellschaft
Cornelia Mueller
Radboud Universiteit
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Gibwa Musoke
Universiteit Van Amsterdam
Radboud Universiteit
Ioannis Myserlis
Institut de Radioastronomie Millimétrique (IRAM)
Hiroshi Nagai
National Astronomical Observatory of Japan
The Graduate University for Advanced Studies (SOKENDAI)
Neil M. Nagar
Universidad de Concepción
Dhanya G. Nair
Max-Planck-Gesellschaft
Universidad de Concepción
Masanori Nakamura
National Institute of Technology (KOSEN)
Academia Sinica
Gopal Narayanan
University of Massachusetts
Iniyan Natarajan
Harvard-Smithsonian Center for Astrophysics
Harvard University
Antonios Nathanail
Academy of Athens
Johann Wolfgang Goethe Universität Frankfurt am Main
Santiago Navarro Fuentes
Institut de Radioastronomie Millimétrique (IRAM)
Joey Neilsen
Villanova University
Chunchong Ni
University of Waterloo
Perimeter Institute for Theoretical Physics
Michael A. Nowak
Washington University in St. Louis
Junghwan Oh
Joint Institute for VLBI in Europe (JIVE)
Hiroki Okino
National Astronomical Observatory of Japan
University of Tokyo
Hector Raul Olivares Sanchez
Centre For Research And Development In Mathematics And Applications (CIDMA)
Universidade de Aveiro
Tomoaki Oyama
National Astronomical Observatory of Japan
Feryal Ozel
Georgia Institute of Technology
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Harvard-Smithsonian Center for Astrophysics
Harvard University
Georgios Filippos Paraschos
Max-Planck-Gesellschaft
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Academia Sinica
Kyung Hee University
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James Clerk Maxwell Telescope
East Asian Observatory
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Harvard-Smithsonian Center for Astrophysics
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Academia Sinica
Canadian Institute for Advanced Research
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University of Toronto
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Harvard University
Harvard-Smithsonian Center for Astrophysics
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Institut de Radioastronomie Millimétrique (IRAM)
Aleksandar PopStefanija
University of Massachusetts
Oliver Porth
Universiteit Van Amsterdam
Johann Wolfgang Goethe Universität Frankfurt am Main
Ben Prather
University of Illinois
Giacomo Principe
Istituto Nazionale di Fisica Nucleare
Istituto nazionale di astrofisica (INAF)
Universita degli Studi di Trieste
Italian ALMA Regional Centre
Dimitrios Psaltis
Georgia Institute of Technology
Hung-Yi Pu
National Taiwan Normal University
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Harvard-Smithsonian Center for Astrophysics
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James Clerk Maxwell Telescope
East Asian Observatory
Gemini Observatory North
Luciano Rezzolla
Trinity College Dublin
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Frankfurt Institute for Advanced Studies
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University of Toronto
Perimeter Institute for Theoretical Physics
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Consejo Superior de Investigaciones Científicas (CSIC)
Freek Roelofs
Radboud Universiteit
Cristina Romero-Canizales
Academia Sinica
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Max-Planck-Gesellschaft
Arash Roshanineshat
University of Arizona
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Max-Planck-Gesellschaft
Alan L. Roy
Max-Planck-Gesellschaft
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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
Instituto Nacional de Astrofísica, Óptica y Electrońica
Consejo Nacional de Ciencia y Tecnologia Mexico
Miguel Sanchez-Portal
Institut de Radioastronomie Millimétrique (IRAM)
Mahito Sasada
Tokyo Institute of Technology
National Astronomical Observatory of Japan
Hiroshima University
Kaushik Satapathy
University of Arizona
Saurabh
Max-Planck-Gesellschaft
Tuomas Savolainen
Max-Planck-Gesellschaft
Aalto-Yliopisto
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-Gesellschaft
Zhiqiang Shen
Chinese Academy of Sciences
Sasikumar Silpa
Universidad de Concepción
Des Small
Joint Institute for VLBI in Europe (JIVE)
Bong Won Sohn
University of Science and Technology (UST)
Korea Astronomy and Space Science Institute
Yonsei University
Jason SooHoo
Massachusetts Institute of Technology (MIT)
Kamal Souccar
University of Massachusetts
Joshua S. Stanway
University of Central Lancashire
He Sun
Beijing University of Technology
Fumie Tazaki
Tokyo Electron Technology Solutions Limited
Paul Tiede
Harvard University
Harvard-Smithsonian Center for Astrophysics
Remo P. J. Tilanus
Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)
Universiteit Leiden
University of Arizona
Radboud Universiteit
Michael Titus
Massachusetts Institute of Technology (MIT)
Kenji Toma
Tohoku University
Pablo Torne
Max-Planck-Gesellschaft
Institut de Radioastronomie Millimétrique (IRAM)
Teresa Toscano
Consejo Superior de Investigaciones Científicas (CSIC)
Efthalia Traianou
Max-Planck-Gesellschaft
Consejo Superior de Investigaciones Científicas (CSIC)
Tyler Trent
University of Arizona
Sascha Trippe
Seoul National University
Matthew Turk
University of Illinois
Ilse van Bemmel
Netherlands Institute for Radio Astronomy (ASTRON)
Huib Jan van Langevelde
Joint Institute for VLBI in Europe (JIVE)
University of New Mexico
Universiteit Leiden
Daniel R. van Rossum
Radboud Universiteit
Jesse Vos
Radboud Universiteit
Jan Wagner
Max-Planck-Gesellschaft
Derek Ward-Thompson
University of Central Lancashire
John Wardle
Brandeis University
Jonathan Weintroub
Harvard-Smithsonian Center for Astrophysics
Harvard University
Robert Wharton
Max-Planck-Gesellschaft
Kaj Wiik
Aalto-Yliopisto
Turun Yliopisto
Gunther Witzel
Max-Planck-Gesellschaft
Michael F. Wondrak
Radboud Universiteit
John Conway
Chalmers, Rymd-, geo- och miljövetenskap, Onsala rymdobservatorium
Anne-Kathrin Baczko
Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik
George N. Wong
Institute for Advanced Study
Princeton University
Qingwen Wu
Huazhong University of Science and Technology
Nitika Yadlapalli
California Institute of Technology (Caltech)
Paul Yamaguchi
Harvard-Smithsonian Center for Astrophysics
Aristomenis Yfantis
Radboud Universiteit
Doosoo Yoon
Universiteit Van Amsterdam
Andre Young
Radboud Universiteit
Ziri Younsi
University College London (UCL)
Johann Wolfgang Goethe Universität Frankfurt am Main
Wei Yu
Harvard-Smithsonian Center for Astrophysics
Feng Yuan
Fudan University
Ye-Fei Yuan
University of Science and Technology of China
Ai-Ling Zeng
Consejo Superior de Investigaciones Científicas (CSIC)
J. Anton Zensus
Max-Planck-Gesellschaft
Shuo Zhang
Michigan State University
Guang-Yao Zhao
Consejo Superior de Investigaciones Científicas (CSIC)
Max-Planck-Gesellschaft
Shan-Shan Zhao
Chinese Academy of Sciences
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 708 A179Ämneskategorier (SSIF 2025)
Atom- och molekylfysik och optik
Astronomi, astrofysik och kosmologi
Meteorologi och atmosfärsvetenskap
DOI
10.1051/0004-6361/202556759