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arXiv 1005.0844astro-ph.COastro-ph.GAastro-ph.HE
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对超大质量黑洞标度关系演化的理解

Towards an understanding of the evolution of the scaling relations for supermassive black holes

C. M. Booth, Joop Schaye

摘要:

位于大多数星系中心的超大质量黑洞(BH)的生长与驱动星系本身形成的物理过程交织在一起。因此,黑洞的质量(m_BH)与其宿主性质之间关系的演化代表了星系形成过程的关键方面。我们使用的宇宙学模拟,以及分析模型,调查如何以及为什么BH的标度关系随宇宙时间的演变。我们发现,模拟再现了观测到的m_BH与其宿主星系性质之间的红移零关系,以及群内介质的热力学分布,也再现了观测到的大质量星系的m_BH/m_s比值的演化,尽管m_BH/sigma关系的演化与观测明显矛盾。模拟结果表明,星系及其暗物质晕的结合能与m_BH之间的关系不随红移而变化,而m_BH/m_halo的比值随红移而增大. Booth & Schaye(2010)的简单解析模型,其中黑洞的质量由其宿主晕的引力结合能控制,定量地再现了后两个结果。最后,对于低红移(z<1)的大质量星系(m_s~10^11 M_sun),如果这些星系主要通过干合并而生长,我们可以解释它们的m_BH与其宿主星系的恒星成分的质量和结合能之间关系的演化。

英文摘要:

The growth of the supermassive black holes (BHs) that reside at the centres of most galaxies is intertwined with the physical processes that drive the formation of the galaxies themselves. The evolution of the relations between the mass of the BH, m_BH, and the properties of its host therefore represent crucial aspects of the galaxy formation process. We use a cosmological simulation, as well as an analytical model, to investigate how and why the scaling relations for BHs evolve with cosmic time. We find that a simulation that reproduces the observed redshift zero relations between m_BH and the properties of its host galaxy, as well as the thermodynamic profiles of the intragroup medium, also reproduces the observed evolution in the ratio m_BH/m_s for massive galaxies, although the evolution of the m_BH/sigma relation is in apparent conflict with observations. The simulation predicts that the relations between m_BH and the binding energies of both the galaxy and its dark matter halo do not evolve, while the ratio m_BH/m_halo increases with redshift. The simple, analytic model of Booth & Schaye (2010), in which the mass of the BH is controlled by the gravitational binding energy of its host halo, quantitatively reproduces the latter two results. Finally, we can explain the evolution in the relations between m_BH and the mass and binding energy of the stellar component of its host galaxy for massive galaxies (m_s~10^11 M_sun) at low redshift (z<1) if these galaxies grow primarily through dry mergers.

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