What Is the Accretion Rate in Sagittarius A*?
What Is the Accretion Rate in Sagittarius A*?
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DOI：
10.1086/312035
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发表时间：
1999-03
期刊：
影响因子：
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通讯作者：
E. Quataert;R. Narayan;M. Reid
中科院分区：
文献类型：
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作者：
E. Quataert;R. Narayan;M. Reid
我们银河系中心的射电源射手座A* 被认为是一个2.6×106 M的黑洞，它从附近恒星的风中吸积气体。我们表明，银河系中心的X射线和红外辐射的限制提供了一个上限~8×10-5 M yr-1的质量吸积率在Sgr A*。平流主导的吸积流（ADAF）模型支持10-5 M/yr的速率。相比之下，利用观测到的质量损失恒星的空间分布并假设没有相互作用的恒星风，估计Sgr A* 的邦迪吸积速率约为3×10-5 M/yr-1。因此，Sgr A* 的Bondi、ADAF和X射线推断的吸积率之间存在大致一致。我们讨论了这些估计的不确定性，强调钱德拉X射线天文台即将进行的观测的重要性，收紧X射线衍生的限制。
The radio source Sagittarius A* at the center of our Galaxy is believed to be a 2.6×106 M black hole that accretes gas from the winds of nearby stars. We show that limits on the X-ray and infrared emission from the Galactic center provide an upper limit of ~8×10-5 M yr-1 on the mass accretion rate in Sgr A*. The advection-dominated accretion flow (ADAF) model favors a rate of ≲10-5 M☉ yr-1. In comparison, the Bondi accretion rate onto Sgr A*, estimated using the observed spatial distribution of mass-losing stars and assuming noninteracting stellar winds, is ~3×10-5 M☉ yr-1. Thus, there is rough agreement between the Bondi, the ADAF, and the X-ray-inferred accretion rates for Sgr A*. We discuss uncertainties in these estimates, emphasizing the importance of upcoming observations by the Chandra X-ray Observatory for tightening the X-ray-derived limits.