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Title: Probing the Magnetic Field Structure in Sgr A* on Black Hole Horizon Scales with Polarized Radiative Transfer Simulations

Abstract

Magnetic fields are believed to drive accretion and relativistic jets in black hole accretion systems, but the magnetic field structure that controls these phenomena remains uncertain. We perform general relativistic (GR) polarized radiative transfer of time-dependent three-dimensional GR magnetohydrodynamical simulations to model thermal synchrotron emission from the Galactic Center source Sagittarius A* (Sgr A*). We compare our results to new polarimetry measurements by the Event Horizon Telescope (EHT) and show how polarization in the visibility (Fourier) domain distinguishes and constrains accretion flow models with different magnetic field structures. These include models with small-scale fields in disks driven by the magnetorotational instability as well as models with large-scale ordered fields in magnetically arrested disks. We also consider different electron temperature and jet mass-loading prescriptions that control the brightness of the disk, funnel-wall jet, and Blandford–Znajek-driven funnel jet. Our comparisons between the simulations and observations favor models with ordered magnetic fields near the black hole event horizon in Sgr A*, though both disk- and jet-dominated emission can satisfactorily explain most of the current EHT data. We also discuss how the black hole shadow can be filled-in by jet emission or mimicked by the absence of funnel jet emission. We show that strongermore » model constraints should be possible with upcoming circular polarization and higher frequency (349 GHz) measurements.« less

Authors:
;  [1]; ;  [2]
  1. Department of Physics and Joint Space-Science Institute, University of Maryland, College Park, MD 20742 (United States)
  2. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
Publication Date:
OSTI Identifier:
22661206
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 837; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCRETION DISKS; BLACK HOLES; COMPARATIVE EVALUATIONS; ELECTRON TEMPERATURE; EMISSION; FLOW MODELS; GALAXIES; GHZ RANGE; LIMITING VALUES; MAGNETIC FIELDS; MAGNETOHYDRODYNAMICS; MASS; POLARIZATION; RADIANT HEAT TRANSFER; RELATIVISTIC RANGE; SIMULATION; TELESCOPES; THREE-DIMENSIONAL CALCULATIONS; TIME DEPENDENCE

Citation Formats

Gold, Roman, McKinney, Jonathan C., Johnson, Michael D., and Doeleman, Sheperd S. Probing the Magnetic Field Structure in Sgr A* on Black Hole Horizon Scales with Polarized Radiative Transfer Simulations. United States: N. p., 2017. Web. doi:10.3847/1538-4357/AA6193.
Gold, Roman, McKinney, Jonathan C., Johnson, Michael D., & Doeleman, Sheperd S. Probing the Magnetic Field Structure in Sgr A* on Black Hole Horizon Scales with Polarized Radiative Transfer Simulations. United States. doi:10.3847/1538-4357/AA6193.
Gold, Roman, McKinney, Jonathan C., Johnson, Michael D., and Doeleman, Sheperd S. Fri . "Probing the Magnetic Field Structure in Sgr A* on Black Hole Horizon Scales with Polarized Radiative Transfer Simulations". United States. doi:10.3847/1538-4357/AA6193.
@article{osti_22661206,
title = {Probing the Magnetic Field Structure in Sgr A* on Black Hole Horizon Scales with Polarized Radiative Transfer Simulations},
author = {Gold, Roman and McKinney, Jonathan C. and Johnson, Michael D. and Doeleman, Sheperd S.},
abstractNote = {Magnetic fields are believed to drive accretion and relativistic jets in black hole accretion systems, but the magnetic field structure that controls these phenomena remains uncertain. We perform general relativistic (GR) polarized radiative transfer of time-dependent three-dimensional GR magnetohydrodynamical simulations to model thermal synchrotron emission from the Galactic Center source Sagittarius A* (Sgr A*). We compare our results to new polarimetry measurements by the Event Horizon Telescope (EHT) and show how polarization in the visibility (Fourier) domain distinguishes and constrains accretion flow models with different magnetic field structures. These include models with small-scale fields in disks driven by the magnetorotational instability as well as models with large-scale ordered fields in magnetically arrested disks. We also consider different electron temperature and jet mass-loading prescriptions that control the brightness of the disk, funnel-wall jet, and Blandford–Znajek-driven funnel jet. Our comparisons between the simulations and observations favor models with ordered magnetic fields near the black hole event horizon in Sgr A*, though both disk- and jet-dominated emission can satisfactorily explain most of the current EHT data. We also discuss how the black hole shadow can be filled-in by jet emission or mimicked by the absence of funnel jet emission. We show that stronger model constraints should be possible with upcoming circular polarization and higher frequency (349 GHz) measurements.},
doi = {10.3847/1538-4357/AA6193},
journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 837,
place = {United States},
year = {2017},
month = {3}
}