eprintid: 10190893 rev_number: 10 eprint_status: archive userid: 699 dir: disk0/10/19/08/93 datestamp: 2024-04-18 09:51:39 lastmod: 2024-04-18 10:05:11 status_changed: 2024-04-18 10:05:11 type: article metadata_visibility: show sword_depositor: 699 creators_name: Akiyama, K creators_name: Alberdi, A creators_name: Alef, W creators_name: Algaba, JC creators_name: Anantua, R creators_name: Asada, K creators_name: Azulay, R creators_name: Bach, U creators_name: Baczko, AK creators_name: Ball, D creators_name: Baloković, M creators_name: Bandyopadhyay, B creators_name: Barrett, J creators_name: Bauböck, M creators_name: Benson, BA creators_name: Bintley, D creators_name: Blackburn, L creators_name: Blundell, R creators_name: Bouman, KL creators_name: Bower, GC creators_name: Boyce, H creators_name: Bremer, M creators_name: Brinkerink, CD creators_name: Brissenden, R creators_name: Britzen, S creators_name: Broderick, AE creators_name: Broguiere, D creators_name: Bronzwaer, T creators_name: Bustamante, S creators_name: Byun, DY creators_name: Carlstrom, JE creators_name: Ceccobello, C creators_name: Chael, A creators_name: Chan, CK creators_name: Chang, DO creators_name: Chatterjee, K creators_name: Chatterjee, S creators_name: Chen, MT creators_name: Chen, Y creators_name: Cheng, X creators_name: Cho, I creators_name: Christian, P creators_name: Conroy, NS creators_name: Conway, JE creators_name: Cordes, JM creators_name: Crawford, TM creators_name: Crew, GB creators_name: Cruz-Osorio, A creators_name: Cui, Y creators_name: Dahale, R creators_name: Davelaar, J creators_name: De Laurentis, M creators_name: Deane, R creators_name: Dempsey, J creators_name: Desvignes, G creators_name: Dexter, J creators_name: Dhruv, V creators_name: Dihingia, IK creators_name: Doeleman, SS creators_name: Dougall, S creators_name: Dzib, SA creators_name: Eatough, RP creators_name: Emami, R creators_name: Falcke, H creators_name: Farah, J creators_name: Fish, VL creators_name: Fomalont, E creators_name: Ford, HA creators_name: Foschi, M creators_name: Fraga-Encinas, R creators_name: Freeman, WT creators_name: Friberg, P creators_name: Fromm, CM creators_name: Fuentes, A creators_name: Galison, P creators_name: Gammie, CF creators_name: García, R creators_name: Gentaz, O creators_name: Georgiev, B creators_name: Goddi, C creators_name: Gold, R creators_name: Gómez-Ruiz, AI creators_name: Gómez, JL creators_name: Gu, M creators_name: Gurwell, M creators_name: Hada, K creators_name: Haggard, D creators_name: Haworth, K creators_name: Hecht, MH creators_name: Hesper, R creators_name: Heumann, D creators_name: Ho, LC creators_name: Ho, P creators_name: Honma, M creators_name: Huang, CWL creators_name: Huang, L creators_name: Hughes, DH creators_name: Ikeda, S creators_name: Violette Impellizzeri, CM creators_name: Inoue, M title: First Sagittarius A* Event Horizon Telescope Results. VIII. Physical Interpretation of the Polarized Ring ispublished: pub divisions: UCL divisions: B04 divisions: C06 divisions: F63 note: Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence, https://creativecommons.org/licenses/by/4.0/. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. abstract: 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. date: 2024-04-01 date_type: published publisher: American Astronomical Society official_url: http://dx.doi.org/10.3847/2041-8213/ad2df1 oa_status: green full_text_type: pub language: eng primo: open primo_central: open_green verified: verified_manual elements_id: 2268362 doi: 10.3847/2041-8213/ad2df1 lyricists_name: Younsi, Ziri lyricists_id: ZYOUN45 actors_name: Bracey, Alan actors_id: ABBRA90 actors_role: owner full_text_status: public publication: The Astrophysical Journal Letters volume: 964 number: 2 article_number: L26 issn: 2041-8205 citation: Akiyama, K; Alberdi, A; Alef, W; Algaba, JC; Anantua, R; Asada, K; Azulay, R; ... Inoue, M; + view all <#> Akiyama, K; Alberdi, A; Alef, W; Algaba, JC; Anantua, R; Asada, K; Azulay, R; Bach, U; Baczko, AK; Ball, D; Baloković, 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, DY; Carlstrom, JE; Ceccobello, C; Chael, A; Chan, CK; Chang, DO; Chatterjee, K; Chatterjee, S; Chen, MT; 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; De Laurentis, M; Deane, R; Dempsey, J; Desvignes, G; Dexter, J; Dhruv, V; Dihingia, IK; Doeleman, SS; Dougall, S; 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, CWL; Huang, L; Hughes, DH; Ikeda, S; Violette Impellizzeri, CM; Inoue, M; - view fewer <#> (2024) First Sagittarius A* Event Horizon Telescope Results. VIII. Physical Interpretation of the Polarized Ring. The Astrophysical Journal Letters , 964 (2) , Article L26. 10.3847/2041-8213/ad2df1 <https://doi.org/10.3847/2041-8213%2Fad2df1>. Green open access document_url: https://discovery.ucl.ac.uk/id/eprint/10190893/1/The_Event_Horizon_Telescope_Collaboration_2024_ApJL_964_L26.pdf