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arXiv 0708.3733astro-ph
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收音机大声AGN的亮度函数、尺寸和FR二分法

Luminosity function, sizes and FR dichotomy of radio-loud AGN

Christian R. Kaiser, Philip N. Best

摘要:

射电星系和射电噪类星体的射电光度函数(RLF)通常被建模为破幂律。破裂光度接近于这些物体的大尺度射电结构的两个Fanaroff-Riley(FR)形态类之间的分界线。我们使用一个分析模型的光度和大小演变的FRI型对象连同一个简单的处方FRI型源构建RLF。我们假设,所有的来源开始与FRII型形态。较弱的喷流随后在其宿主星系的准恒定密度核心内分裂,并发展出FRI型的湍流叶。用这个模型,我们恢复的斜率的幂律和RLF从观测确定的断裂光度。具有喷流功率为$Q$的活动星系核在宇宙中出现的速率与$Q^{-1.6}$成正比。该模型还粗略地预测了FRII型物体的射电瓣大小的分布,如果湍流射流的射电光度在中断点显着下降。我们表明,我们的模型是一致的,最近的想法,两个不同的吸积模式在喷流生产活动星系核,如果吸积过程的辐射效率与喷流功率。

英文摘要:

The radio luminosity function (RLF) of radio galaxies and radio-loud quasars is often modelled as a broken power-law. The break luminosity is close to the dividing line between the two Fanaroff-Riley (FR) morphological classes for the large-scale radio structure of these objects. We use an analytical model for the luminosity and size evolution of FRII-type objects together with a simple prescription for FRI-type sources to construct the RLF. We postulate that all sources start out with an FRII-type morphology. Weaker jets subsequently disrupt within the quasi-constant density cores of their host galaxies and develop turbulent lobes of type FRI. With this model we recover the slopes of the power laws and the break luminosity of the RLF determined from observations. The rate at which AGN with jets of jet power $Q$ appear in the universe is found to be proportional to $Q^{-1.6}$. The model also roughly predicts the distribution of the radio lobe sizes for FRII-type objects, if the radio luminosity of the turbulent jets drops significantly at the point of disruption. We show that our model is consistent with recent ideas of two distinct accretion modes in jet-producing AGN, if radiative efficiency of the accretion process is correlated with jet power.

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