Quasi-stars: accreting black holes inside massive envelopes
Quasi-stars: accreting black holes inside massive envelopes
复制标题
准恒星：在巨大的包层内吸积黑洞
DOI：
--
复制
发表时间：
2007
期刊：
影响因子：
--
通讯作者：
P. Armitage
中科院分区：
文献类型：
--
作者：
M. Begelman;E. Rossi;P. Armitage
我们研究的结构和演化的“准恒星”，吸积黑洞嵌入在大量的流体静力学气体信封。这些配置可以模拟超大质量黑洞种子的早期生长。黑洞的吸积速率会调整，使得对流包层携带的光度等于总质量的爱丁顿极限，M*+MBH <$M*。这大大超过了爱丁顿对黑洞质量的限制，导致黑洞的快速增长。我们使用解析模型和恒星结构的数值计算来研究类星的结构和演化。我们证明了包层的光球温度是Tph M−2/5 BHM 7/20*，当黑洞质量增加时，光球温度随时间减小。一旦Tph < 104 K，光球层的不透明度急剧下降，Tph达到一个极限值，类似于红巨星和原恒星的Hayashi轨迹，低于这个极限值，对流包层就不存在流体静力学解。对于无金属（第三族）的不透明体，该极限温度约为4000 K。当准星达到这个极限温度后，它会被辐射压力迅速驱散。我们发现，质量在103到104兆质量之间的黑洞种子可以通过这种机制在不到几百万年的时间内形成。
We study the structure and evolution of ‘quasi-stars’, accreting black holes embedded within massive hydrostatic gaseous envelopes. These configurations may model the early growth of supermassive black hole seeds. The accretion rate on to the black hole adjusts so that the luminosity carried by the convective envelope equals the Eddington limit for the total mass, M*+MBH≈M*. This greatly exceeds the Eddington limit for the black hole mass alone, leading to rapid growth of the black hole. We use analytic models and numerical stellar structure calculations to study the structure and evolution of quasi-stars. We show that the photospheric temperature of the envelope scales as Tph∝M−2/5BHM7/20*, and decreases with time while the black hole mass increases. Once Tph < 104 K, the photospheric opacity drops precipitously and Tph hits a limiting value, analogous to the Hayashi track for red giants and protostars, below which no hydrostatic solution for the convective envelope exists. For metal-free (Population III) opacities, this limiting temperature is approximately 4000 K. After a quasi-star reaches this limiting temperature, it is rapidly dispersed by radiation pressure. We find that black hole seeds with masses between 103 and 104 M⊙ could form via this mechanism in less than a few Myr.