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arXiv 1104.3858astro-ph.COastro-ph.GAastro-ph.HE
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第一个大质量黑洞的种子和它们的起源

The First Massive Black Hole Seeds and Their Hosts

Jillian Bellovary, Marta Volonteri, Fabio Governato, Sijing Shen, Thomas Quinn, James Wadsley

摘要:

我们研究了高红移星系中第一个大质量黑洞的形成,目的是提供关于哪些星系有或没有大质量黑洞的见解。在SPH+ N体宇宙学模拟中,我们采用了一种新的方法在星系晕中形成种子黑洞。大质量黑洞种子的形成直接取决于局部气体密度、温度和金属丰度,并受大质量黑洞形成的物理模型的激励。我们探讨种子黑洞人口作为晕质量和红移的函数,并研究如何改变大规模黑洞种子形成的效率影响黑洞和它们的主机之间的关系。种子黑洞倾向于形成质量在10^7 ~ 10^9 Msun之间的晕,由于金属在星系际介质中的扩散,在z = 5附近的形成速率受到抑制。我们发现大质量黑洞的形成时间和黑洞的占有率是宿主晕质量的函数。当z = 5时,质量M_halo > 3 x 10^9 Msun的晕拥有大质量黑洞,而与种子形成效率无关,而较小晕的占据分数随着黑洞形成效率的增加而增加。我们的模拟解释了为什么大质量黑洞会出现在一些无球星系和矮星系中,但我们也预测它们在低质量系统中的出现会越来越罕见。

英文摘要:

We investigate the formation of the first massive black holes in high redshift galaxies, with the goal of providing insights to which galaxies do or do not host massive black holes. We adopt a novel approach to forming seed black holes in galaxy halos in cosmological SPH+N-body simulations. The formation of massive black hole seeds is dictated directly by the local gas density, temperature, and metallicity, and motivated by physical models of massive black hole formation. We explore seed black hole populations as a function of halo mass and redshift, and examine how varying the efficiency of massive black hole seed formation affects the relationship between black holes and their hosts. Seed black holes tend to form in halos with mass between 10^7 and 10^9 Msun, and the formation rate is suppressed around z = 5 due to the diffusion of metals throughout the intergalactic medium. We find that the time of massive black hole formation and the occupation fraction of black holes are a function of the host halo mass. By z = 5, halos with mass M_halo > 3 x 10^9 Msun host massive black holes regardless of the efficiency of seed formation, while the occupation fraction for smaller halos increases with black hole formation efficiency. Our simulations explain why massive black holes are found in some bulgeless and dwarf galaxies, but we also predict that their occurrence becomes rarer and rarer in low-mass systems.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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