Quasar Evolution Driven by Galaxy Encounters in Hierarchical Structures
Quasar Evolution Driven by Galaxy Encounters in Hierarchical Structures
复制标题
星系在层次结构中相遇所驱动的类星体演化
DOI：
10.1086/375337
复制
发表时间：
2003
期刊：
影响因子：
--
通讯作者：
V. Vittorini
中科院分区：
文献类型：
--
作者：
N. Menci;A. Cavaliere;A. Fontana;E. Giallongo;F. Poli;V. Vittorini
我们链接的星系的演化在等级聚类的情况下，不断变化的吸积率的冷气体到中央的大质量黑洞的权力类星体。我们专注于星系的相互作用作为吸积的主要触发器，相关的标度律是从Cavaliere & Vittorini和嫁接到星系形成的半解析代码。结果，在高z时，原星系通过等级合并迅速增长;同时，大量新鲜气体被输入，也不稳定，所以黑洞以其最大的爱丁顿速率被填充。在z值较低的地方，星系动力学事件主要是在等级不断增长的星系群中相遇;现在，随着残余气体耗尽，不稳定的相遇减少，燃料补给逐渐消失。因此，除了恒星观测所需的参数调整外，我们的模型唯一地产生了从z = 6到2.5的上升，而对于z < 2.5，明亮的类星体数量的下降与观察到的一样陡峭。此外，我们的结果与观测到的类星体的光度函数、它们在z = 5 ~ 0的不同星等的空间密度以及局域mBH-σ关系都很好地拟合。
We link the evolution of the galaxies in the hierarchical clustering scenario with the changing accretion rates of cold gas onto the central massive black holes that power the quasars. We focus on galaxy interactions as main triggers of accretion; the related scaling laws are taken from Cavaliere & Vittorini and grafted to a semianalytic code for galaxy formation. As a result, at high z the protogalaxies grow rapidly by hierarchical merging; meanwhile, much fresh gas is imported and also destabilized, so the holes are fueled at their full Eddington rates. At lower z the galactic dynamical events are mostly encounters in hierarchically growing groups; now the refueling peters out, as the residual gas is exhausted while the destabilizing encounters dwindle. So, with no parameter tuning other than that needed for stellar observables, our model uniquely produces a rise from z ≈ 6 to 2.5, and for z < 2.5 a decline of the bright quasar population as steep as observed. In addition, our results closely fit the observed luminosity functions of quasars, their space density at different magnitudes from z ≈ 5 to 0, and the local mBH-σ relation.