The Astrophysical Journal Letters (Jan 2024)

First Sagittarius A* Event Horizon Telescope Results. VIII. Physical Interpretation of the Polarized Ring

  • The Event Horizon Telescope Collaboration,
  • Kazunori Akiyama,
  • Antxon Alberdi,
  • Walter Alef,
  • Juan Carlos Algaba,
  • Richard Anantua,
  • Keiichi Asada,
  • Rebecca Azulay,
  • Uwe Bach,
  • Anne-Kathrin Baczko,
  • David Ball,
  • Mislav Baloković,
  • Bidisha Bandyopadhyay,
  • John Barrett,
  • Michi Bauböck,
  • Bradford A. Benson,
  • Dan Bintley,
  • Lindy Blackburn,
  • Raymond Blundell,
  • Katherine L. Bouman,
  • Geoffrey C. Bower,
  • Hope Boyce,
  • Michael Bremer,
  • Christiaan D. Brinkerink,
  • Roger Brissenden,
  • Silke Britzen,
  • Avery E. Broderick,
  • Dominique Broguiere,
  • Thomas Bronzwaer,
  • Sandra Bustamante,
  • Do-Young Byun,
  • John E. Carlstrom,
  • Chiara Ceccobello,
  • Andrew Chael,
  • Chi-kwan Chan,
  • Dominic O. Chang,
  • Koushik Chatterjee,
  • Shami Chatterjee,
  • Ming-Tang Chen,
  • Yongjun Chen,
  • Xiaopeng Cheng,
  • Ilje Cho,
  • Pierre Christian,
  • Nicholas S. Conroy,
  • John E. Conway,
  • James M. Cordes,
  • Thomas M. Crawford,
  • Geoffrey B. Crew,
  • Alejandro Cruz-Osorio,
  • Yuzhu Cui,
  • Rohan Dahale,
  • Jordy Davelaar,
  • Mariafelicia De Laurentis,
  • Roger Deane,
  • Jessica Dempsey,
  • Gregory Desvignes,
  • Jason Dexter,
  • Vedant Dhruv,
  • Indu K. Dihingia,
  • Sheperd S. Doeleman,
  • Sean Dougall,
  • Sergio A. Dzib,
  • Ralph P. Eatough,
  • Razieh Emami,
  • Heino Falcke,
  • Joseph Farah,
  • Vincent L. Fish,
  • Edward Fomalont,
  • H. Alyson Ford,
  • Marianna Foschi,
  • Raquel Fraga-Encinas,
  • William T. Freeman,
  • Per Friberg,
  • Christian M. Fromm,
  • Antonio Fuentes,
  • Peter Galison,
  • Charles F. Gammie,
  • Roberto García,
  • Olivier Gentaz,
  • Boris Georgiev,
  • Ciriaco Goddi,
  • Roman Gold,
  • Arturo I. Gómez-Ruiz,
  • José L. Gómez,
  • Minfeng Gu,
  • Mark Gurwell,
  • Kazuhiro Hada,
  • Daryl Haggard,
  • Kari Haworth,
  • Michael H. Hecht,
  • Ronald Hesper,
  • Dirk Heumann,
  • Luis C. Ho,
  • Paul Ho,
  • Mareki Honma,
  • Chih-Wei L. Huang,
  • Lei Huang,
  • David H. Hughes,
  • Shiro Ikeda,
  • C. M. Violette Impellizzeri,
  • Makoto Inoue,
  • Sara Issaoun,
  • David J. James,
  • Buell T. Jannuzi,
  • Michael Janssen,
  • Britton Jeter,
  • Wu Jiang,
  • Alejandra Jiménez-Rosales,
  • Michael D. Johnson,
  • Svetlana Jorstad,
  • Abhishek V. Joshi,
  • Taehyun Jung,
  • Mansour Karami,
  • Ramesh Karuppusamy,
  • Tomohisa Kawashima,
  • Garrett K. Keating,
  • Mark Kettenis,
  • Dong-Jin Kim,
  • Jae-Young Kim,
  • Jongsoo Kim,
  • Junhan Kim,
  • Motoki Kino,
  • Jun Yi Koay,
  • Prashant Kocherlakota,
  • Yutaro Kofuji,
  • Patrick M. Koch,
  • Shoko Koyama,
  • Carsten Kramer,
  • Joana A. Kramer,
  • Michael Kramer,
  • Thomas P. Krichbaum,
  • Cheng-Yu Kuo,
  • Noemi La Bella,
  • Tod R. Lauer,
  • Daeyoung Lee,
  • Sang-Sung Lee,
  • Po Kin Leung,
  • Aviad Levis,
  • Zhiyuan Li,
  • Rocco Lico,
  • Greg Lindahl,
  • Michael Lindqvist,
  • Mikhail Lisakov,
  • Jun Liu,
  • Kuo Liu,
  • Elisabetta Liuzzo,
  • Wen-Ping Lo,
  • Andrei P. Lobanov,
  • Laurent Loinard,
  • Colin J. Lonsdale,
  • Amy E. Lowitz,
  • Ru-Sen Lu,
  • Nicholas R. MacDonald,
  • Jirong Mao,
  • Nicola Marchili,
  • Sera Markoff,
  • Daniel P. Marrone,
  • Alan P. Marscher,
  • Iván Martí-Vidal,
  • Satoki Matsushita,
  • Lynn D. Matthews,
  • Lia Medeiros,
  • Karl M. Menten,
  • Daniel Michalik,
  • Izumi Mizuno,
  • Yosuke Mizuno,
  • James M. Moran,
  • Kotaro Moriyama,
  • Monika Moscibrodzka,
  • Wanga Mulaudzi,
  • Cornelia Müller,
  • Hendrik Müller,
  • Alejandro Mus,
  • Gibwa Musoke,
  • Ioannis Myserlis,
  • Andrew Nadolski,
  • Hiroshi Nagai,
  • Neil M. Nagar,
  • Masanori Nakamura,
  • Gopal Narayanan,
  • Iniyan Natarajan,
  • Antonios Nathanail,
  • Santiago Navarro Fuentes,
  • Joey Neilsen,
  • Roberto Neri,
  • Chunchong Ni,
  • Aristeidis Noutsos,
  • Michael A. Nowak,
  • Junghwan Oh,
  • Hiroki Okino,
  • Héctor Olivares,
  • Gisela N. Ortiz-León,
  • Tomoaki Oyama,
  • Feryal Özel,
  • Daniel C. M. Palumbo,
  • Georgios Filippos Paraschos,
  • Jongho Park,
  • Harriet Parsons,
  • Nimesh Patel,
  • Ue-Li Pen,
  • Dominic W. Pesce,
  • Vincent Piétu,
  • Richard Plambeck,
  • Aleksandar PopStefanija,
  • Oliver Porth,
  • Felix M. Pötzl,
  • Ben Prather,
  • Jorge A. Preciado-López,
  • Dimitrios Psaltis,
  • Hung-Yi Pu,
  • Venkatessh Ramakrishnan,
  • Ramprasad Rao,
  • Mark G. Rawlings,
  • Alexander W. Raymond,
  • Luciano Rezzolla,
  • Angelo Ricarte,
  • Bart Ripperda,
  • Freek Roelofs,
  • Alan Rogers,
  • Cristina Romero-Cañizales,
  • Eduardo Ros,
  • Arash Roshanineshat,
  • Helge Rottmann,
  • Alan L. Roy,
  • Ignacio Ruiz,
  • Chet Ruszczyk,
  • Kazi L. J. Rygl,
  • Salvador Sánchez,
  • David Sánchez-Argüelles,
  • Miguel Sánchez-Portal,
  • Mahito Sasada,
  • Kaushik Satapathy,
  • Tuomas Savolainen,
  • F. Peter Schloerb,
  • Jonathan Schonfeld,
  • Karl-Friedrich Schuster,
  • Lijing Shao,
  • Zhiqiang Shen,
  • Des Small,
  • Bong Won Sohn,
  • Jason SooHoo,
  • León David Sosapanta Salas,
  • Kamal Souccar,
  • Joshua S. Stanway,
  • He Sun,
  • Fumie Tazaki,
  • Alexandra J. Tetarenko,
  • Paul Tiede,
  • Remo P. J. Tilanus,
  • Michael Titus,
  • Pablo Torne,
  • Teresa Toscano,
  • Efthalia Traianou,
  • Tyler Trent,
  • Sascha Trippe,
  • Matthew Turk,
  • Ilse van Bemmel,
  • Huib Jan van Langevelde,
  • Daniel R. van Rossum,
  • Jesse Vos,
  • Jan Wagner,
  • Derek Ward-Thompson,
  • John Wardle,
  • Jasmin E. Washington,
  • Jonathan Weintroub,
  • Robert Wharton,
  • Maciek Wielgus,
  • Kaj Wiik,
  • Gunther Witzel,
  • Michael F. Wondrak,
  • George N. Wong,
  • Qingwen Wu,
  • Nitika Yadlapalli,
  • Paul Yamaguchi,
  • Aristomenis Yfantis,
  • Doosoo Yoon,
  • André Young,
  • Ken Young,
  • Ziri Younsi,
  • Wei Yu,
  • Feng Yuan,
  • Ye-Fei Yuan,
  • J. Anton Zensus,
  • Shuo Zhang,
  • Guang-Yao Zhao,
  • Shan-Shan Zhao,
  • Mahdi Najafi-Ziyazi

DOI
https://doi.org/10.3847/2041-8213/ad2df1
Journal volume & issue
Vol. 964, no. 2
p. L26

Abstract

Read online

In a companion paper, we present the first spatially resolved polarized image of Sagittarius A* on event horizon scales, captured using the Event Horizon Telescope, a global very long baseline interferometric array operating at a wavelength of 1.3 mm. Here we interpret this image using both simple analytic models and numerical general relativistic magnetohydrodynamic (GRMHD) simulations. The large spatially resolved linear polarization fraction (24%–28%, peaking at ∼40%) is the most stringent constraint on parameter space, disfavoring models that are too Faraday depolarized. Similar to our studies of M87*, polarimetric constraints reinforce a preference for GRMHD models with dynamically important magnetic fields. Although the spiral morphology of the polarization pattern is known to constrain the spin and inclination angle, the time-variable rotation measure (RM) of Sgr A* (equivalent to ≈46° ± 12° rotation at 228 GHz) limits its present utility as a constraint. If we attribute the RM to internal Faraday rotation, then the motion of accreting material is inferred to be counterclockwise, contrary to inferences based on historical polarized flares, and no model satisfies all polarimetric and total intensity constraints. On the other hand, if we attribute the mean RM to an external Faraday screen, then the motion of accreting material is inferred to be clockwise, and one model passes all applied total intensity and polarimetric constraints: a model with strong magnetic fields, a spin parameter of 0.94, and an inclination of 150°. We discuss how future 345 GHz and dynamical imaging will mitigate our present uncertainties and provide additional constraints on the black hole and its accretion flow.

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