First Sagittarius A* Event Horizon Telescope Results. VII. Polarization of the Ring
: Akiyama K, Alberdi A, Alef W, Algaba JC, Anantua R, Asada K, Azulay R, Bach U, Baczko A, Ball D, Balokovic M, Bandyopadhyay B, Barrett J, Bauböck M, Benson BA, Bintley D, Blackburn L, Blundell R, Bouman KL, Bower GC, Boyce H, Bremer M, Brinkerink CD, Brissenden R, Britzen S, Broderick AE, Broguiere D, Bronzwaer T, Bustamante S, Byun D, Carlstrom JE, Ceccobello C, Chael A, Chan C, Chang DO, Chatterjee K, Chatterjee S, Chen M, Chen Y, Cheng X, Cho I, Christian P, Conroy NS, Conway JE, Cordes JM, Crawford TM, Crew GB, Cruz-Osorio A, Cui Y, Dahale R, Davelaar J, Laurentis MD, Deane R, Dempsey J, Desvignes G, Dexter J, Dhruv V, Dihingia IK, Doeleman SS, Dougal ST, Dzib SA, Eatough RP, Emami R, Falcke H, Farah J, Fish VL, Fomalont E, Ford HA, Foschi M, Fraga-Encinas R, Freeman WT, Friberg P, Fromm CM, Fuentes A, Galison P, Gammie CF, García R, Gentaz O, Georgiev B, Goddi C, Gold R, Gómez-Ruiz AI, Gómez JL, Gu M, Gurwell M, Hada K, Haggard D, Haworth K, Hecht MH, Hesper R, Heumann D, Ho LC, Ho P, Honma M, Huang CL, Huang L, Hughes DH, Ikeda S, Impellizzeri CMV, Inoue M, Issaoun S, James DJ, Jannuzi BT, Janssen M, Jeter B, Jiang W, Jiménez-Rosales A, Johnson MD, Jorstad S, Joshi AV, Jung T, Karami M, Karuppusamy R, Kawashima T, Keating GK, Kettenis M, Kim D, Kim J, Kim J, Kim J, Kino M, Koay JY, Kocherlakota P, Kofuji Y, Koch PM, Koyama S, Kramer C, Kramer JA, Kramer M, Krichbaum TP, Kuo C, Bella NL, Lauer TR, Lee D, Lee S, Leung PK, Levis A, Li Z, Lico R, Lindahl G, Lindqvist M, Lisakov M, Liu J, Liu K, Liuzzo E, Lo W, Lobanov AP, Loinard L, Lonsdale CJ, Lowitz AE, Lu R, MacDonald NR, Mao J, Marchili N, Markoff S, Marrone DP, Marscher AP, Martí-Vidal I, Matsushita S, Matthews LD, Medeiros L, Menten KM, Michalik D, Mizuno I, Mizuno Y, Moran JM, Moriyama K, Moscibrodzka M, Mulaudzi W, Müller C, Müller H, Mus A, Musoke G, Myserlis I, Nadolski A, Nagai H, Nagar NM, Nakamura M, Narayanan G, Natarajan I, Nathanail A, Fuentes SN, Neilsen J, Neri R, Ni C, Noutsos A, Nowak MA, Oh J, Okino H, Olivares H, Ortiz-León GN, Oyama T, Özel F, Palumbo DCM, Paraschos GF, Park J, Parsons H, Patel N, Pen U, Pesce DW, Piétu V, Plambeck R, PopStefanija A, Porth O, Pötzl FM, Prather B, Preciado-López JA, Psaltis D, Pu H, Ramakrishnan V, Rao R, Rawlings MG, Raymond AW, Rezzolla L, Ricarte A, Ripperda B, Roelofs F, Rogers A, Romero-Cañizales C, Ros E, Roshanineshat A, Rottmann H, Roy AL, Ruiz I, Ruszczyk C, Rygl KLJ, Sánchez S, Sánchez-Argüelles D, Sánchez-Portal M, Sasada M, Satapathy K, Savolainen T, Schloerb FP, Schonfeld J, Schuster K, Shao L, Shen Z, Small D, Sohn BW, SooHoo J, Salas LDS, Souccar K, Stanway JS, Sun H, Tazaki F, Tetarenko AJ, Tiede P, Tilanus RPJ, Titus M, Torne P, Toscano T, Traianou E, Trent T, Trippe S, Turk M, Bemmel I, Langevelde HJ, Rossum DR, Vos J, Wagner J, Ward-Thompson D, Wardle J, Washington JE, Weintroub J, Wharton R, Wielgus M, Wiik K, Witzel G, Wondrak MF, Wong GN, Wu Q, Yadlapalli N, Yamaguchi P, Yfantis A, Yoon D, Young A, Young K, Younsi Z, Yu W, Yuan F, Yuan Y, Zensus JA, Zhang S, Zhao G, Zhao S; Event Horizon Telescope Collaboration
Publisher: Institute of Physics Publishing
: 2024
: Astrophysical Journal Letters
: The Astrophysical Journal Letters
: L25
: 964
: 2
: 2041-8213
DOI: https://doi.org/10.3847/2041-8213/ad2df0
: https://dx.doi.org/10.3847/2041-8213/ad2df0
: https://research.utu.fi/converis/portal/detail/Publication/387502746
The Event Horizon Telescope observed the horizon-scale synchrotron emission region around the Galactic center supermassive black hole, Sagittarius A* (Sgr A*), in 2017. These observations revealed a bright, thick ring morphology with a diameter of 51.8 ± 2.3 μas and modest azimuthal brightness asymmetry, consistent with the expected appearance of a black hole with mass M ≈ 4 × 106 M ⊙. From these observations, we present the first resolved linear and circular polarimetric images of Sgr A*. The linear polarization images demonstrate that the emission ring is highly polarized, exhibiting a prominent spiral electric vector polarization angle pattern with a peak fractional polarization of ∼40% in the western portion of the ring. The circular polarization images feature a modestly (∼5%–10%) polarized dipole structure along the emission ring, with negative circular polarization in the western region and positive circular polarization in the eastern region, although our methods exhibit stronger disagreement than for linear polarization. We analyze the data using multiple independent imaging and modeling methods, each of which is validated using a standardized suite of synthetic data sets. While the detailed spatial distribution of the linear polarization along the ring remains uncertain owing to the intrinsic variability of the source, the spiraling polarization structure is robust to methodological choices. The degree and orientation of the linear polarization provide stringent constraints for the black hole and its surrounding magnetic fields, which we discuss in an accompanying publication.
