Mass Accretion onto a Black Hole

我们研究了黑洞的质量吸积，比较了X射线瞬变（黑洞候选者）和低质量X射线双星（LMXB）。本研究取得的主要结果如下：1.在X射线瞬变和低质量X射线双星的X射线谱中都有两个分量。这两个组成部分之一是共同的X射线源，是很好的拟合模型谱预计从吸积盘。这两个来源的时间变异性是非常低的。这些证据表明，在黑洞和中子星周围都存在具有相似性质的吸积盘.另一个分量在X射线瞬态中由低功率谱拟合，而在LMXB中由黑体谱拟合。这个成分可能是从黑洞和中子星附近的区域发射出来的。两个源中的第二分量都表现出与盘分量无关的大的时变。这一证据表明，除了普通的吸积盘（光学厚而几何薄的吸积盘）外，中心星星上还存在另一条质量吸积通道，我们认为，光学厚而几何薄的吸积盘夹在光学薄而几何厚的吸积盘中，从而产生了强烈的时间变化。

We have studied the mass accretion onto a black hole, comparing the X-ray transients(black hole candidates) with the low mass X-ray binaries(LMXB). The main results obtained in this study are summarized as follows.1. There are two components in the X-ray spectra of both X-ray transients and low mass X-ray binaries. One of the two components is common in both X-ray sources and is well fitted by the model spectrum expected from the accretion disk. The time variability of this components is very low in both sources. These evidence indicates that the accretion disks with similar properties exist around both black holes and neutron stars.2. another component is fitted by a power low spectrum in X-ray transients, while by a blackbody spectrum in LMXBs. This component may be emitted from the region close to the black hole and the neutron star.3. The second component in both sources exhibits a large time variation independentry of the disk component. This evidence indicates that there exist another channel for mass accretion onto the central star besides the ordinary accretion disk(optically thick and geometriaclly thin disk).We propose that the optically thick and geometrically thin disk is sandwiched in the optically thin and geometrically thick disk, which givers rise to the intense time variation.