THE SUBMILLIMETER BUMP IN Sgr A* FROM RELATIVISTIC MHD SIMULATIONS

By J. Dexter, E. Agol, P. Chris Fragile, J. McKinney. 2010

161 citations recorded by the source corpus.

Recent high resolution observations of the Galactic center black hole allow for direct comparison with accretion disk simulations. We compare two-temperature synchrotron emission models from three-dimensional, general relativistic magnetohydrodynamic simulations to millimeter observations of Sgr A*. Fits to very long baseline interferometry and spectral index measurements disfavor the monochromatic face-on black hole shadow models from our previous work. Inclination angles ⩽20° are ruled out to 3σ. We estimate the inclination and position angles of the black hole, as well as the electron temperature of the accretion flow and the accretion rate, to be , , Te = (5.4 ± 3.0) × 1010 K, and , respectively, with 90% confidence. The black hole shadow is unobscured in all best-fit models, and may be detected by observations on baselines between Chile and California, Arizona, or Mexico at 1.3 mm or .87 mm either through direct sampling of the visibility amplitude or using closure phase information. Millimeter flaring behavior consistent with the observations is present in all viable models and is caused by magnetic turbulence in the inner radii of the accretion flow. The variability at optically thin frequencies is strongly correlated with that in the accretion rate. The simulations provide a universal picture of the 1.3 mm emission region as a small region near the midplane in the inner radii of the accretion flow, which is roughly isothermal and has ν/νc ∼ 1–20, where νc is the critical frequency for thermal synchrotron emission.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/d8aa844df1db368a617105b65ec516c1ee00d573

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Citations in the corpus

A public code for general relativistic, polarised radiative transfer around spinning black holes (2016, methodology): “As a final example, we show images and polarisation maps from the HARM fluid model in Figure 8 with parameters chosen to model the submm bump in Sgr A* (e.g., Mościbrodzka et al. 2009; Dexter et al. 2010).”
General relativistic magnetohydrodynamic simulations of magnetically choked accretion flows around black holes (2012, unknown): “For SgrA* with Φ ∼ 0.1pc2G, M ≈ 4.5×106M , mass accretion rate ṁH ∼ 1.5×10−6 (Dexter et al. 2010), one obtains rn=0m ∼ 1011rg, rn=1m ∼ 107rg, and ΥH ∼ 109.”
TESTING THE NO-HAIR THEOREM WITH EVENT HORIZON TELESCOPE OBSERVATIONS OF SAGITTARIUS A* (2013, result): “…have already exhibited a non-trivial agreement with the RIAF models, suggesting that these form a credible set of models for the purposes of imaging currently (Broderick et al. 2009; Huang et al. 2009; Dexter et al. 2010; Broderick et al. 2011b; Shcherbakov et al. 2012; Dexter & Fragile 2013).”
EVIDENCE FOR LOW BLACK HOLE SPIN AND PHYSICALLY MOTIVATED ACCRETION MODELS FROM MILLIMETER-VLBI OBSERVATIONS OF SAGITTARIUS A* (2010, methodology): “…magnetohydrodynamic and radiative-hydrodynamic simulations playing a central role (De Villiers et al. 2005; McKinney 2006; Hawley & Krolik 2006; Beckwith et al. 2008; McKinney & Blandford 2009; Tchekhovskoy et al. 2010; Dexter et al. 2010; Penna et al. 2010; Kurosawa & Proga 2009).”
The size of the jet launching region in M87 (2011, methodology): “In their simulation initialised with a dipolar magnetic field (MBD in Dexter et al. 2010, and here), an ultra-relativistic jet is produced self-consistently from an accretion disc and propagates stably out to 1000 M before it interacts with the simulation boundary.2 We perform general relativistic…”
On the charge of the Galactic centre black hole (2018, methodology): “To explain the synchrotron emission of flares on the event-horizon scales, a magnetic field of the order of ∼ 10–100 G is required (Falcke & Markoff 2000; Mościbrodzka et al. 2009; Dexter et al. 2010; Eckart et al. 2012).”
Hot Accretion Flows Around Black Holes (2014, methodology): “…model (Huang et al. 2007, Broderick et al. 2011) and in numerous studies based on MHD simulations (Goldston et al. 2005; Noble et al. 2007; Sharma et al. 2007b, 2008; Mościbrodzka et al. 2009; Chan et al. 2009; Kato et al. 2009; Dexter et al. 2010; Shcherbakov et al. 2012; Dexter & Fragile 2013).”
IPOLE - semi-analytic scheme for relativistic polarized radiative transport (2017, background): “…et al. 2000; Noble et al. 2007; Broderick et al. 2009; Broderick & Loeb 2009a; Dexter & Agol 2009; Mościbrodzka et al. 2009; Yuan et al. 2009; Dexter et al. 2010; Broderick et al. 2011a,b; Dexter & Fragile 2011; Vincent et al. 2011; Dexter et al. 2012; Dolence et al. 2012; Mościbrodzka et…”
Detection of orbital motions near the last stable circular orbit of the massive black hole SgrA* (2018, background): “Early estimates of the orientation of the hot gas in the innermost accretion zone based on radio data suggest a similar orientation as well (Ω ∼ 128..157◦ E. of N. (note 180◦ degeneracy), yet higher inclination i ∼ 50..68◦, Dexter et al. 2010; Broderick et al. 2011; Wang et al. 2013).”
A Reconnection Switch to Trigger gamma-Ray Burst Jet Dissipation (2010, background): “This may have important implications for polarized disc and jet emission and composition (see e.g. Broderick & McKinney 2010; Dexter et al. 2010; Shcherbakov, Penna & McKinney 2010).”
PHOTON RINGS AROUND KERR AND KERR-LIKE BLACK HOLES (2013, methodology): “Mościbrodzka et al. (2009) and Dexter et al. (2009, 2010) fitted the VLBI and spectral data to sets of images obtained from three-dimensional general-relativistic magnetohydrodynamic (3D-GRMHD) simulations (Gammie et al. 2003; Fragile et al. 2007, 2009; McKinney & Blandford 2009).”