Quasar clustering in a galaxy and quasar formation model based on ultra high-resolution N-body simulations
Quasar clustering in a galaxy and quasar formation model based on ultra high-resolution N-body simulations
复制标题
基于超高分辨率 N 体模拟的星系中的类星体聚类和类星体形成模型
DOI：
10.1093/mnrasl/slv169
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发表时间：
2016
影响因子：
4.8
通讯作者：
Masahiro Nagashima
中科院分区：
文献类型：
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作者：
Taira Oogi;Motohiro Enoki;Tomoaki Ishiyama;Masakazu A. R. Kobayashi;Ryu Makiya;Masahiro Nagashima
我们使用一种新版本的星系和类星体形成的半解析模型和最先进的N体宇宙学模拟来研究类星体的成团性质。在这项研究中，我们假设星系的重大合并触发了超大质量黑洞和类星体活动中的冷气吸积。我们的模型可以再现类星体演化的缩小趋势。我们发现类星体宿主暗物质晕的质量中值随宇宙时间从z=0.4(几个1011m⊙)到z=1(几个1012M⊙)增加了一个数量级，并且只与类星体的光度有微弱的依赖关系。通过模型中的类星体-星系互相关函数来推导类星体的偏差，我们发现类星体的偏差并不依赖于类星体的光度，这与观测到的趋势相似。这一结果反映了这样一个事实，即具有固定光度的类星体具有不同的爱丁顿比，因此具有不同的宿主晕质量，这主要决定了类星体的偏差。我们还发现类星体的偏差随着红移的增加而增加，这与观测结果定性地一致。我们的偏差值低于高红移时的观测值，这意味着我们需要一些机制来使类星体在低质量晕中不活跃，和/或使它们在高质量晕中更活跃。
We investigate clustering properties of quasars using a new version of our semi-analytic model of galaxy and quasar formation with state-of-the-art cosmologicalN-body simulations. In this study, we assume that a major merger of galaxies triggers cold gas accretion on to a supermassive black hole and quasar activity. Our model can reproduce the downsizing trend of the evolution of quasars. We find that the median mass of quasar host dark matter haloes increases with cosmic time by an order of magnitude fromz= 4 (a few 1011M⊙) toz= 1 (a few 1012M⊙), and depends only weakly on the quasar luminosity. Deriving the quasar bias through the quasar–galaxy cross-correlation function in the model, we find that the quasar bias does not depend on the quasar luminosity, similar to observed trends. This result reflects the fact that quasars with a fixed luminosity have various Eddington ratios and thus have various host halo masses that primarily determine the quasar bias. We also show that the quasar bias increases with redshift, which is in qualitative agreement with observations. Our bias value is lower than the observed values at high redshifts, implying that we need some mechanisms that make quasars inactive in low-mass haloes and/or that make them more active in high-mass haloes.