Three-dimensional radiative properties of hot accretion flows on to the Galactic Centre black hole
Three-dimensional radiative properties of hot accretion flows on to the Galactic Centre black hole
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DOI：
10.1111/j.1365-2966.2009.15645.x
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发表时间：
2009-06
影响因子：
4.8
通讯作者：
Y. Kato;M. Umemura;K. Ohsuga
中科院分区：
文献类型：
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作者：
Y. Kato;M. Umemura;K. Ohsuga
通过求解辐射传输方程，我们研究了银河系中心超大质量黑洞附近磁流体动力学吸积流模型的三维辐射性质，该模型符合观测到的Sgr A* 光谱.结果发现，射电辐射的核心比事件视界阴影的尺寸大，其峰值位置偏离引力中心。我们还发现，自吸收同步辐射所产生的热电子的叠加在几十个史瓦西半径可以占低于临界频率v c <$10 12 Hz的低频光谱。在临界频率以上，来自热电子的同步自康普顿辐射可以解释最近近红外观测中发现的可变辐射。与Ohsuga，Kato & Mineshige的研究相反，我们发现不同质量吸积率下的热电子韧致辐射所产生的X射线谱与Chandra观测到的Sgr A* 的耀斑态和静止态都是一致的。
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 v c ≈ 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.