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Paper: 3-D Radiative Properties of Hot Accretion Flows onto the Galactic Center Black Hole
Volume: 439, The Galactic Center: a Window to the Nuclear Environment of Disk Galaxies
Page: 368
Authors: Kato, Y.
Abstract: By solving radiative transfer equations (Kato et al. 2009), we examine three-dimensional radiative properties of magnetohydrodynamic (MHD) accretion flows confronting with the observed spectrum of Sgr A*, in the vicinity of supermassive black hole at the Galactic center. Models of magnetized accretion flows we used here are identical to that of Kato (2004) which report quasi-periodic oscillations (QPOs). We find that the core of radio emission is larger than the size of the event horizon shadow and its peak location is shifted from the gravitational center. The self-absorbed synchrotron emission by the superposition of thermal electrons within a few tens of the Schwarzschild radius can account for low-frequency spectra below the critical frequency approximately 1012 Hz. Above the critical frequency, the synchrotron self-Compton emission by thermal electrons can account for variable emissions in recent near-infrared observations. The X-ray spectra by Bremsstrahlung emission of thermal electrons for the different mass accretion rates can be consistent with both the flaring state and the quiescent state of Sgr A* observed by Chandra. We will discuss a possible origin of QPOs in Sgr A* and its spin in the context of disk seismology by using recently detected QPOs.
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