研究成果・発表論文

Three-dimensional radiative properties of hot accretion flows on to the Galactic Centre black hole

Kato, Y.,   Umemura, M.,   & Ohsuga, K.


要旨
By solving the radiative transfer equations, we examine the three- dimensional radiative properties of a magnetohydrodynamic accretion flow model conforming to the observed spectrum of Sgr A* in the vicinity of the supermassive black hole at the Galactic Centre. As a result, we find that the core of the radio emission is larger than the size of the event horizon shadow and its peak location is shifted from the gravitational centre. We also find that the self-absorbed synchrotron emission arising from the superposition of thermal electrons within a few tens of the Schwartzschild radius can account for low-frequency spectra below the critical frequency \ensuremathν$_c$ åisebox-0.5ex~ 10$^12$Hz. Above the critical frequency, the synchrotron self-Compton emission from thermal electrons can account for the variable emission found in recent near-infrared observations. In contrast to a previous study by Ohsuga, Kato & Mineshige, we found that the X-ray spectra arising from 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.






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