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arXiv 1706.04775astro-ph.GAastro-ph.CO
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SZ团簇样品中高红移AGN反馈的研究

A Study of High-redshift AGN Feedback in SZ Cluster Samples

L. Bîrzan, D. A. Rafferty, M. Brüggen, H. T. Intema

摘要:

利用从南极望远镜和阿塔卡马宇宙学望远镜巡天中选取的星系团样本,研究了在高红移($0.3<z<1.2$)下活动星系核的反馈。在附近的系统的研究相比,我们没有发现冷却流集群和非冷却流集群之间的分离的基础上的中央射电源的射电光度。这种缺乏可能是由于在较高的红移,触发AGN活动的星系星系合并的发生率增加。为了支持这种情况,我们发现了中央射电源的射电光度函数演化的证据:虽然低光度源没有太多的演化,但高光度源在更高的红移处出现的频率强烈增加。我们解释这一演变为在$z>0.6$大质量星系团中的高激发射电星系(HERG)的增加,这意味着从HERG模式吸积过渡到低功率低激发射电星系(LERG)模式吸积在中等红移。此外,我们使用本地无线电到喷气功率缩放关系来估计反馈功率,并发现在我们的样本中,一半的冷却流系统可能有足够的热量来平衡冷却。然而,我们假设,当地的关系可能不太适合预测反馈功率在高光度的HERG,因为它们是来自主要由低光度LERG的样本。

英文摘要:

We present a study of AGN feedback at higher redshifts ($0.3<z<1.2$) using Sunyaev-Zel'dovich (SZ) selected samples of clusters from the South-Pole Telescope and Atacama Cosmology Telescope surveys. In contrast to studies of nearby systems, we do not find a separation between cooling flow clusters and non-cooling flow clusters based on the radio luminosity of the central radio source. This lack may be due to the increased incidence of galaxy-galaxy mergers at higher redshift that triggers AGN activity. In support of this scenario, we find evidence for evolution in the radio luminosity function of the central radio source: while the lower-luminosity sources do not evolve much, the higher-luminosity sources show a strong increase in the frequency of their occurrence at higher redshifts. We interpret this evolution as an increase in high-excitation radio galaxies (HERGs) in massive clusters at $z>0.6$, implying a transition from HERG-mode accretion to lower-power low-excitation radio galaxy (LERG)-mode accretion at intermediate redshifts. Additionally, we use local radio-to-jet power scaling relations to estimate feedback power and find that half of the cooling flow systems in our sample probably have enough heating to balance cooling. However, we postulate that the local relations are likely not well suited to predict feedback power in high-luminosity HERGs, as they are derived from samples composed mainly of lower-luminosity LERGs.

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