在群体和集群中FRII的寿命：对无线电模式反馈的影响
The Lifetime of FRIIs in Groups and Clusters: Implications for Radio-Mode Feedback
摘要：
利用Berlind SDSS星表与VLA FIRST巡天的互相关，计算了26个中央星系团中52个FRII射电源的最大寿命t_max。FRII源的模拟目录，以匹配的选择标准的FIRST和我们的母样本的红移分布，而分析模型被用来计算源的大小和光度。FRII源的最大寿命，然后确定通过比较观察到的和模型预测的长度分布。我们估计FRII的平均寿命为1.5x10^7年，占空比约为8x10^8年。t_max和模型参数之间的简并：射流功率分布，轴比，能量注入指数和环境密度在我们的寿命估计中最多引入两个不确定性的因子。此外，我们还计算了几个星系团和宿主星系的性质的函数的中央星系团的射电活动星系核（AGN）的分数。这里记录的射电源的寿命与类星体的寿命是一致的，即使这些FRII有大量的次爱丁顿吸积。这些结果为活动星系核能量注入的反馈模型提供了一个基准时间框架。如果给定扩展射电源的形态由大尺度环境决定，而寿命由吸积物理学的细节决定，则FRII寿命与所有扩展射电源都相关。
英文摘要：
We determine the maximum lifetime t_max of 52 FRII radio sources found in 26 central group galaxies from cross correlation of the Berlind SDSS group catalog with the VLA FIRST survey. Mock catalogs of FRII sources were produced to match the selection criteria of FIRST and the redshift distribution of our parent sample, while an analytical model was used to calculate source sizes and luminosities. The maximum lifetime of FRII sources was then determined via a comparison of the observed and model projected length distributions. We estimate the average FRII lifetime is 1.5x10^7 years and the duty cycle is ~8x10^8 years. Degeneracies between t_max and the model parameters: jet power distribution, axial ratio, energy injection index, and ambient density introduce at most a factor of two uncertainty in our lifetime estimate. In addition, we calculate the radio active galactic nuclei (AGN) fraction in central group galaxies as a function of several group and host galaxy properties. The lifetime of radio sources recorded here is consistent with the quasar lifetime, even though these FRIIs have substantially sub-Eddington accretion. These results suggest a fiducial time frame for energy injection from AGN in feedback models. If the morphology of a given extended radio source is set by large-scale environment, while the lifetime is determined by the details of the accretion physics, this FRII lifetime is relevant for all extended radio sources.
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