关于发光高红移类星体的辐射效率、爱丁顿比和占空比
On the radiative efficiencies, Eddington ratios, and duty cycles of luminous high-redshift quasars
摘要：
本文利用斯隆数字巡天（Sloan Digital Sky Survey）对活动星系核（AGN）在z=3-6的光度函数的测量，特别是最近对z =3-4.5的类星体成团的测量，研究了高红移活动星系核的特征辐射效率ε、爱丁顿比λ和占空比P_0。模型的自由参数为ε，λ，以及黑洞质量\mbh与晕维里速度V_vir之间关系的归一化、散射和红移演化。我们根据黑洞质量函数的隐含增长计算了光度函数，根据宿主晕的偏差计算了类星体的关联长度。我们测试我们所采用的公式的晕质量函数和晕偏置对测量的大型N体模拟开发的MICE合作。在z=3，特别是z=4时观察到的活动星系核的强烈聚集意味着大质量的黑洞存在于稀有的大质量暗物质晕中。再现观测到的光度函数需要高效率ε和/或低爱丁顿比λ，下限（基于与测量的z=4相关长度的2σ一致性）ε> 0.7λ/（1+0.7λ），这意味着当λ> 0.25时ε> 0.17。成功的模型预测了高占空比，在z=3.1，4.5和6时，分别为P_0~0.2，0.5和0.9，它们要求锁定在中心黑洞中的晕重子的分数远大于局部观测值。在z>7时，大质量和稀有的宿主晕的丰度迅速下降，这意味着发光类星体的数量密度也相应地迅速下降，这比简单地外推z=3-6的光度函数所预测的要强得多。（节略）
英文摘要：
We investigate the characteristic radiative efficiency ε, Eddington ratio λ, and duty cycle P_0 of high-redshift active galactic nuclei (AGN), drawing on measurements of the AGN luminosity function at z=3-6 and, especially, on recent measurements of quasar clustering at z=3-4.5 from the Sloan Digital Sky Survey. The free parameters of our models are ε, λ, and the normalization, scatter, and redshift evolution of the relation between black hole mass \mbh and halo virial velocity V_vir. We compute the luminosity function from the implied growth of the black hole mass function and the quasar correlation length from the bias of the host halos. We test our adopted formulae for the halo mass function and halo bias against measurements from the large N-body simulation developed by the MICE collaboration. The strong clustering of AGNs observed at z=3 and, especially, at z=4 implies that massive black holes reside in rare, massive dark matter halos. Reproducing the observed luminosity function then requires high efficiency εand/or low Eddington ratio λ, with a lower limit (based on 2σagreement with the measured z=4 correlation length) ε> 0.7λ/(1+0.7λ), implying ε> 0.17 for λ> 0.25. Successful models predict high duty cycles, P_0~0.2, 0.5, and 0.9 at z=3.1, 4.5 and 6, respectively, and they require that the fraction of halo baryons locked in the central black hole is much larger than the locally observed value. The rapid drop in the abundance of the massive and rare host halos at z>7 implies a proportionally rapid decline in the number density of luminous quasars, much stronger than simple extrapolations of the z=3-6 luminosity function would predict. (abridged)
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