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arXiv 1102.1437astro-ph.CO
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黑洞的晕占据分布:对质量的依赖

The Halo Occupation Distribution of Black Holes: Dependence on Mass

Colin DeGraf, Matthew Oborski, Tiziana Di Matteo, Suchetana Chatterjee, Daisuke Nagai, Zheng Zheng, Jonathan Richardson

摘要:

我们研究了直接跟随黑洞生长的流体动力学宇宙学模拟中黑洞的晕占据分布(HOD)。类似于星系/暗晕的HOD,我们发现黑洞占据数可以用与1+(M_Host)^alpha成比例的形式N_BH来描述,其中alpha随着红移温和地演化,表明在低红移下的给定质量晕(M_Host)倾向于比在高红移下拥有更少的黑洞(正如星系和黑洞合并的结果所预期的那样)。我们进一步划分的占领数的贡献,从黑洞居住在中央和卫星星系内的晕。晕内的M_BH的分布倾向于由单个大质量BH(分布在与M_Host强相关的峰值质量附近)和相对低质量的次级BH的集合组成,与M_Host的相关性较弱。我们还研究了其主机晕内的BH的空间分布,并发现它们通常遵循幂律径向分布(即更集中的比subhalo分布)。最后,我们表征的主机质量BH的增长是反馈为主(如恒星形成淬火)。我们发现,M_Host > 3 * 10^12 M_sun的晕具有由z~3控制的反馈的初级BH,低质量的晕在较低的红移处变得越来越受影响。

英文摘要:

We investigate the halo occupation distribution (HOD) of black holes within a hydrodynamic cosmological simulation that directly follows black hole growth. Similar to the HOD of galaxies/subhalos, we find that the black hole occupation number can be described by the form N_BH proportional to 1+ (M_Host)^alpha where alpha evolves mildly with redshift indicating that a given mass halo (M_Host) at low redshift tends to host fewer BHs than at high redshift (as expected as a result of galaxy and BH mergers). We further divide the occupation number into contributions from black holes residing in central and satellite galaxies within a halo. The distribution of M_BH within halos tends to consist of a single massive BH (distributed about a peak mass strongly correlated with M_Host), and a collection of relatively low-mass secondary BHs, with weaker correlation with M_Host. We also examine the spatial distribution of BHs within their host halos, and find they typically follow a power-law radial distribution (i.e. much more centrally concentrated than the subhalo distribution). Finally, we characterize the host mass for which BH growth is feedback dominated (e.g. star formation quenched). We show that halos with M_Host > 3 * 10^12 M_sun have primary BHs that are feedback dominated by z~3 with lower mass halos becoming increasingly more affected at lower redshift.

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