The impact of dust in host galaxies on quasar luminosity functions
The impact of dust in host galaxies on quasar luminosity functions
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宿主星系中的尘埃对类星体光度函数的影响
DOI：
10.1093/mnrasl/slv035
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发表时间：
2015
影响因子：
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通讯作者：
Ryu Makiya
中科院分区：
文献类型：
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作者：
Hikari Shirakata;Takashi Okamoto;Motohiro Enoki;Masahiro Nagashima;Masakazu A. R. Kobayashi;Tomoaki Ishiyama;Ryu Makiya
我们利用半解析星系形成模型结合大宇宙学N体模拟研究了尘埃衰减对类星体atz α 2光度函数的影响。我们估计的尘埃衰减类星体的自洽与星系通过考虑他们的主机隆起的尘埃。我们发现亮类星体的亮度由于尘埃的衰减而强烈地变暗，在B波段的亮度为102等。假设Marconi等人对活动星系核的经验辐射热改正，我们发现这种尘埃衰减太强，不能同时解释B波段和X射线类星体的光度函数。我们考虑两种可能的机制，削弱尘埃衰减。作为这样一种机制，我们引入了AGN活动的时间延迟，也就是说，气体燃料的中央黑洞开始后的某个时候，由一个主要的合并引起的星爆开始。另一个是尘埃分布的各向异性。我们发现，为了使类星体的尘埃衰减可以忽略不计，要么气体吸积到黑洞的动力学时间尺度的至少三倍，其主机隆起或尘埃覆盖因子是小到0.1。
We have investigated effects of dust attenuation on quasar luminosity functions atz∼ 2 using a semi-analytic galaxy formation model combined with a large cosmologicalN-body simulation. We estimate the dust attenuation of quasars self-consistently with that of galaxies by considering the dust in their host bulges. We find that the luminosity of the bright quasars is strongly dimmed by the dust attenuation, ∼2 mag in theB-band. Assuming the empirical bolometric corrections for active galactic nuclei (AGNs) by Marconi et al., we find that this dust attenuation is too strong to explain theB-band and X-ray quasar luminosity functions simultaneously. We consider two possible mechanisms that weaken the dust attenuation. As such a mechanism, we introduce a time delay for AGN activity, that is, gas fuelling to a central black hole starts sometime after the beginning of the starburst induced by a major merger. The other is the anisotropy in the dust distribution. We find that in order to make the dust attenuation of the quasars negligible, either the gas accretion into the black holes has to be delayed at least three times the dynamical time-scale of their host bulges or the dust covering factor is as small as ∼0.1.