The cosmic evolution of radio-AGN feedback to z=1
The cosmic evolution of radio-AGN feedback to z=1
复制标题
DOI：
10.1093/mnras/stu1776
复制
发表时间：
2014-11-21
影响因子：
4.8
通讯作者：
Sabater, J.
中科院分区：
文献类型：
--
作者：
Best, P. N.;Ker, L. M.;Sabater, J.
本文首次测量了z = 1时“喷流模式”（辐射效率低下）射电活动星系核的射电光度函数，以研究射电活动星系核反馈的宇宙演化。8个射电源样品组合产生了211个0.5 < z < 1.0的射电响活动星系核目录，这些活动星系核在光谱上分为喷流型和辐射型（辐射有效）活动星系核。通过与斯隆数字巡天的大样本射电活动星系核的比较，独立地导出了射电活动星系核的射电光度函数的宇宙演化。辐射模式的无线电活动星系核显示出一个数量级的空间密度增加到z 1在所有的光度，符合这些活动星系核的燃料由冷气体。相反，喷流模式射电活动星系核的空间密度在低射电光度（L-14（GHz）小于或接近10（24）W Hz（-1））时随着红移的增加而减小，但在较高的射电光度时增加。简单的模型来解释所观察到的演变。在最佳拟合模型中，喷流模式活动星系核的特征空间密度随着红移而下降，这与大质量静止星系的空间密度下降一致，这些星系通过冷却热晕中的气体来为它们提供燃料。在星星形成的猝灭和喷流型射电活动星系核活动的开始之间可能存在1.5-2 Gyr的时间延迟。在更高的射电光度下的行为可以通过增加喷流模式射电活动星系核活动的特征光度来解释（大约为（1 + z）（3）），或者如果喷流模式射电活动星系核的人口也包括一些贡献的冷气燃料源时，看到他们的吸积率低。更高的红移测量将区分这些可能性。
This paper presents the first measurement of the radio luminosity function of `jet-mode' (radiatively inefficient) radio-AGN out to z = 1, in order to investigate the cosmic evolution of radio-AGN feedback. Eight radio source samples are combined to produce a catalogue of 211 radio-loud AGN with 0.5 < z < 1.0, which are spectroscopically classified into jet-mode and radiative-mode (radiatively efficient) AGN classes. Comparing with large samples of local radio-AGN from the Sloan Digital Sky Survey, the cosmic evolution of the radio luminosity function of each radio-AGN class is independently derived. Radiative-mode radio-AGN show an order of magnitude increase in space density out to z 1 at all luminosities, consistent with these AGN being fuelled by cold gas. In contrast, the space density of jet-mode radio-AGN decreases with increasing redshift at low radio luminosities (L-14 (GHz) less than or similar to 10(24) W Hz(-1)) but increases at higher radio luminosities. Simple models are developed to explain the observed evolution. In the best-fitting models, the characteristic space density of jet-mode AGN declines with redshift in accordance with the declining space density of massive quiescent galaxies, which fuel them via cooling of gas in their hot haloes. A time delay of 1.5-2 Gyr may be present between the quenching of star formation and the onset of jet-mode radio-AGN activity. The behaviour at higher radio luminosities can be explained either by an increasing characteristic luminosity of jet-mode radio-AGN activity with redshift (roughly as (1 + z)(3)) or if the jetmode radio-AGN population also includes some contribution of cold-gas-fuelled sources seen at a time when their accretion rate was low. Higher redshifts measurements would distinguish between these possibilities.