Quasi‐stars and the cosmic evolution of massive black holes
Quasi‐stars and the cosmic evolution of massive black holes
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准恒星和大质量黑洞的宇宙演化
DOI：
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发表时间：
2010
期刊：
影响因子：
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通讯作者：
M. Begelman
中科院分区：
文献类型：
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作者：
M. Volonteri;M. Begelman
我们探索了在类星体(QSS)中形成的大质量黑洞(MBH)种子的宇宙演化，QSS是嵌入在大质量流体静力气态包层中的黑洞。如果流入晕中心的气体超过约1M⊙yr−1，就可能形成这些结构。坍塌的气体捕获了自己的辐射，形成了一颗辐射压力支持的超大质量恒星。当这颗超大质量恒星的核心坍塌时，由此产生的系统就变成了一个类星体。我们使用合并树方法来估计超大质量恒星可能形成的速率作为红移的函数，以及由此产生的QS和种子黑洞种群的统计特性。我们将失控坠落的触发与富含气体的星系的主要合并联系起来，与全球引力不稳定性的阈值联系起来，我们将其与宿主的角动量联系起来。这是我们模型的主要参数。一旦坠落被触发，其速率由晕势决定；由此产生的超大质量恒星、QS和种子黑洞的性质取决于这个速率。在QSS时代之后，我们在合并驱动的增长情景中模拟了MBH在其宿主内的增长。我们比较了在类星体内生长的MBH种子和由第一批无金属恒星的残余物衍生的种子模型，并研究了MBH形成的两个通道同时运行的情况。我们发现，存在有限范围的超大质量恒星/QS/MBH形成效率，这使得人们能够重现观测约束。我们的模型与z=6类星体的密度、MBH的累积质量密度(根据苏伊坦的论点)和当前MBH的质量密度相匹配。计算了MQS≃10 6M⊙的质量函数，并计算了JWST2−10�m带的计数。我们发现，JWST在z≃5−10时，每个场可以检测到多个QSS。
We explore the cosmic evolution of massive black hole (MBH) seeds forming within ‘quasistars’ (QSs), accreting black holes embedded within massive hydrostatic gaseous envelopes. These structures could form if the infall of gas into the center of a halo exceeds about 1 M⊙ yr −1 . The collapsing gas traps its own radiation and forms a radiation pressure-supported supermassive star. When the core of the supermassive star collapses, the resulting system becomes a quasistar. We use a merger-tree approach to estimate the rate at which supermassive stars might form as a function of redshift, and the statistical properties of the resulting QS and seed black hole populations. We relate the triggering of runaway infall to major mergers of gas-rich galaxies, and to a threshold for global gravitational instability, which we link to the angular momentum of the host. This is the main parameter of our models. Once infall is triggered, its rate is determined by the halo potential; the properties of the resulting supermassive star, QS and seed black hole depend on this rate. After the epoch of QSs, we model the growth of MBHs within their hosts in a merger-driven accretion scenario. We compare MBH seeds grown inside quasistars to a seed model that derives from the remnants of the first metal-free stars, and also study the case inwhich both channels of MBH formation operate simultaneously. We find that a limited range of supermassive star/QS/MBH formation efficiencies exists that allows one to reproduce observational constraints. Our models match the density of z = 6 quasars, the cumulative mass density accreted onto MBHs (according to So ltan’s argument), and the current mass density of MBHs. The mass function of QSs peaks at MQS ≃ 10 6 M⊙, and we calculate the number counts for the JWST 2 − 10 �m band. We find that JWST could detect up to several QSs per field at z ≃ 5 − 10.
影响因子：
8.7
作者：
Komatsu, E.;Smith, K. M.;Wright, E. L.
通讯作者：
Wright, E. L.