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arXiv 0910.1379astro-ph.CO
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核星暴驱动的高红移（z>6）类星体的形成

Formation of High-redshift (z>6) Quasars Driven by Nuclear Starbursts

Nozomu Kawakatu, Keiichi Wada

备注：
12 pages, 10 pages, accepted by ApJ
发表信息：
Astrophys.J.706:676-686,2009
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摘要：

基于Kawakatu & Wada（2008）提出的在环核盘（CND）中通过气体吸积生长超大质量黑洞（SMBH）的物理模型，我们描述了高$z$（$z > 6$）类星体（QSO）的形成，其BH质量为M_{BH} > 10^{9} M_{\odot} .我们导出了仅通过气体吸积形成z > 6的类星体的必要条件：（i）宿主星系向CND提供M_{sup} > 10^{10} M_{\odot}的大质量，因为最终BH质量仅占宿主星系提供的总质量的1-10%. (ii)高的恒星形成效率，有利于BH的快速生长。我们还发现，如果黑洞的生长受到爱丁顿吸积的限制，最终的黑洞质量被大大抑制。因此，类星体的形成需要超爱丁顿生长。类星体光度的演化依赖于红移z_{i}，在此红移处吸积到种子黑洞上开始。换句话说，z >6时较亮的类星体有利于SMBH的后期生长（即，z_{i} =10）而不是早期生长（即，z_{i} =30）。此外，我们还预测了z >6时类星体的可观测性质和演化。在类星体阶段，应该存在一个富含恒星的大质量CND，其气体质量约为0.1-1 kpc内动力学质量的10%。另一方面，在BH生长的阶段（即，原类星体阶段），原类星体有一个富含气体的大质量CND，其气体质量与动力学质量相当（删节）。

英文摘要：

Based on the physical model of a supermassive black hole (SMBH) growth via gas accretion in a circumnuclear disk (CND) proposed by Kawakatu & Wada (2008), we describe the formation of high-$z$ ($z > 6$) quasars (QSOs) whose BH masses are M_{BH}> 10^{9} M_{\odot}. We derive the necessary conditions to form QSOs at z > 6 by only gas accretion: (i) A large mass supply with M_{sup} > 10^{10}M_{\odot} from host galaxies to CNDs, because the final BH mass is only 1-10% of the total supplied mass from QSO hosts. (ii) High star formation efficiency for a rapid BH growth. We also find that if the BH growth is limited by the Eddington accretion, the final BH mass is greatly suppressed. Thus, the super-Eddington growth is required for the QSO formation. The evolution of the QSO luminosity depends on the redshift z_{i} at which accretion onto a seed BH is initiated. In other words, the brighter QSOs at z >6 favor the late growth of SMBHs (i.e., z_{i}=10) rather than early growth (i.e., z_{i}=30). Moreover, we predict the observable properties and the evolution of QSOs at z >6. In a QSO phase, there should exist a stellar rich massive CND, whose gas mass is about 10% of the dynamical mass inside 0.1-1 kpc}. On the other hand, in a phase where the BH grows (i.e., a proto-QSO phase), the proto-QSO has a gas rich massive CNDs whose gas mass is comparable to the dynamical mass (abridged).

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