Nonthermal Electrons in Radiatively Inefficient Accretion Flow Models of Sagittarius A*

By F. Yuan, E. Quataert, Ramesh Narayan. 2003

611 citations recorded by the source corpus.

We investigate radiatively inefficient accretion flow models for Sgr A*, the supermassive black hole in our Galactic center, in light of new observational constraints. Confirmation of linear polarization in the submillimeter emission argues for accretion rates much less than the canonical Bondi rate. We consider models with low accretion rates and calculate the spectra produced by a hybrid electron population consisting of both thermal and nonthermal particles. The thermal electrons produce the submillimeter emission and can account for its linear polarization properties. As noted in previous work, the observed low-frequency radio spectrum can be explained if a small fraction (≈1.5%) of the electron thermal energy resides in a soft power-law tail. In the innermost region of the accretion flow, turbulence and/or magnetic reconnection events may occasionally accelerate a fraction of the electrons into a harder power-law tail. We show that the synchrotron emission from these electrons, or the Compton upscattering of synchrotron photons by the same electrons, may account for the X-ray flares observed by Chandra.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/2bcdb2789b455d10849ab3b82cb7054dfa56a7bd

How researchers see this paper

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In Astronomy and Astrophysics

1. Ramesh Narayan
2. T. Johannsen
3. J. McKinney
4. F. Yuan
5. A. Tchekhovskoy
6. R. Genzel
7. A. Sa̧dowski
8. Bing Zhang

In Nuclear and High Energy Physics

1. Ramesh Narayan
2. J. McKinney
3. T. Johannsen
4. A. Tchekhovskoy
5. F. Yuan
6. A. Sa̧dowski
7. J. Dexter
8. Bing Zhang

Citations in the corpus

• THE SUBMILLIMETER BUMP IN Sgr A* FROM RELATIVISTIC MHD SIMULATIONS (2010, background): “The radio spectrum can be explained either by a small amount of the internal energy being injected into nonthermal electrons in the accretion flow (Yuan et al. 2003) or by a short, mildly relativistic, optically thick jet (Falcke & Markoff 2000).”
• An X-Ray, Infrared, and Submillimeter Flare of Sagittarius A* (2007, background): “…of Technology, MS 320-47, Pasadena, CA 91125 11 Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan 12 Department of Astronomy and Radio Astronomy Laboratory, University of California at Berkeley, Campbell Hall, Berkeley, CA 94720 Yuan et al. 2003).”
• Hot Accretion Flows Around Black Holes (2014, methodology): “This has been done using the Yuan et al. (2003) semianalytical 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…”
• Variable Infrared Emission from the Supermassive Black Hole at the Center of the Milky Way (2003, methodology): “It therefore appears at present that the synchrotron only model best fits the available data (e.g., Yuan et al. 2003b).”
• SINFONI in the Galactic Center: Young Stars and Infrared Flares in the Central Light-Month (2005, background): “Our observed slope is in good agreement with the synchrotron models of Yuan et al. (2002, 2003, 2004) and Liu et al. (2004).”
• What drives the growth of black holes (2011, background): “The origin of the flaring emission is a topic of hot debate and may be due to an orbiting hot spot, magnetic heating/reconnection, stochastic acceleration processes, or accretion-rate enhancements (e.g., Markoff et al., 2001; Liu & Melia, 2002; Yuan et al., 2003; Dodds-Eden et al., 2011).”
• First Sagittarius A* Event Horizon Telescope Results. V. Testing Astrophysical Models of the Galactic Center Black Hole (2022, background): “The broad range of values is due to the differences in regions of radio emission in the theoretical models that are considered (ADAFs: Narayan et al. 1998; Yuan et al. 2003; jet models: Falcke et al. 1993; Falcke & Markoff 2000; ADAF+jet models: Yuan et al. 2002).”
• RADIATIVE MODELS OF SGR A* FROM GRMHD SIMULATIONS (2009, methodology): “These could readily be included using a phenomenological prescription for the shape and amplitude of the nonthermal portion of the electron distribution function (Özel et al. 2000; Yuan et al. 2003; Chan et al. 2009), (5) our use of the steady-state approximation in calculating SEDs and images.”
• GLOBAL STRUCTURE OF THREE DISTINCT ACCRETION FLOWS AND OUTFLOWS AROUND BLACK HOLES FROM TWO-DIMENSIONAL RADIATION-MAGNETOHYDRODYNAMIC SIMULATIONS (2011, background): “The emission of nonthermal electrons is thought to be non-trivial (Yuan et al. 2003).”
• Detection of orbital motions near the last stable circular orbit of the massive black hole SgrA* (2018, background): “Theoretical estimates of the magnetic field in the innermost accretion zone around SgrA* vary between 5 and 100 G (Yuan et al. 2003; Mościbrodzka et al. 2009; Dodds-Eden et al. 2010; Dexter et al. 2010; Ponti et al. 2017).”
• 1.3 mm WAVELENGTH VLBI OF SAGITTARIUS A*: DETECTION OF TIME-VARIABLE EMISSION ON EVENT HORIZON SCALES (2010, background): “Physical Models of the Structure of Sgr A* Numerous physically-motivated models have been advanced to explain the multiwavelength emission from Sgr A* (e.g., Falcke et al. 2000; Yuan et al. 2003; Markoff et al. 2007; Noble et al. 2007).”
• Neutrino-dominated Accretion and Supernovae (2005, background): “On the other hand, a model for the accreting supermassive black hole Sgr A at the Galactic center gives s0 0:3 (Yuan et al. 2003).”
• DETECTING FLARING STRUCTURES IN SAGITTARIUS A* WITH HIGH-FREQUENCY VLBI (2008, methodology): “(3) In all of these equations, the radial structure was taken directly from Yuan et al. (2003), and the vertical structure was determined by assuming that the disk height is comparable to the polar radius, ρ.”