An XMM-Newton study of the environments, particle content and impact of low-power radio galaxies
An XMM-Newton study of the environments, particle content and impact of low-power radio galaxies
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DOI：
10.1111/j.1365-2966.2008.13162.x
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发表时间：
2008-02
影响因子：
4.8
通讯作者：
J. Croston;M. Hardcastle;M. Birkinshaw;D. Worrall;R. Laing
中科院分区：
文献类型：
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作者：
J. Croston;M. Hardcastle;M. Birkinshaw;D. Worrall;R. Laing
我们基于xmm -牛顿的新观测和档案资料，对9个低功率（Fanaroff & Riley I型）射电星系样本的环境进行了详细研究。我们报告了在三个射电星系，3C 296， NGC 1044和3C 76.1周围的群体尺度环境的新探测。与先前的研究一样，我们发现FR- I射电星系居住在辐射x射线光度近两个数量级的群体环境中；然而，我们没有发现大尺度x射线环境与射电源特性（如尺寸、射电亮度和轴比）之间存在密切关系的证据。这使我们得出结论，射电源的演化不能完全由热气体的整体特性决定。我们证实了先前的工作，表明等分内部压力通常低于作用在无线电叶上的外部压力，因此必须存在额外的非辐射粒子，或者叶必须是磁性主导的。我们提出了第一个直接观测证据，证明夹带可以提供这种缺失的压力，其形式是射源结构与表观压力不平衡之间的关系。最后，我们的研究提供了进一步的支持，与整个群体相比，在无线电大声群体中存在明显的温度过剩。对于八种温度过剩中的五种，使射电望远镜膨胀所需的能量与通过加热群气体产生这种过剩所需的能量相当；然而，在三种情况下，当前的无线电源似乎太弱，无法产生温度过剩。目前尚不清楚温度过高是否与AGN活动的当前阶段直接相关，或者它是否只是以前AGN活动的标志，或者仅仅是一组最有利于fr - 1射电星系生长的特定群体特性的指标。
We present a detailed study of the environments of a sample of nine low-power (Fanaroff & Riley type I) radio galaxies, based on new and archival XMM-Newtonobservations. We report new detections of group-scale environments around three radio galaxies, 3C 296, NGC 1044 and 3C 76.1. As with previous studies, we find that FR- I radio galaxies inhabit group environments ranging over nearly two orders of magnitude in bolometric X-ray luminosity; however, we find no evidence for a tight relationship between large-scale X-ray environment and radio-source properties such as size, radio luminosity, and axial ratio. This leads us to conclude that radio-source evolution cannot be determined entirely by the global properties of the hot gas. We confirm earlier work showing that equ ipartition internal pressures are typically lower than the external pressures acting on the ra dio lobes, so that additional nonradiating particles must be present or the lobes must be magnetically dominated. We present the first direct observational evidence that entrainment ma y provide this missing pressure, in the form of a relationship between radio-source structure and apparent pressure imbalance. Finally, our study provides further support for the presenc e of an apparent temperature excess in radio-loud groups compared to the group population as a whole. For five of eight temperature excesses, the energy required to inflate the radio l obes is comparable to the energy required to produce this excess by heating of the group gas; however, in three cases the current radio source appears too weak to produce the temperature excess. It remains unclear whether the temperature excess can be directly associated with the current phase of AGN activity, or whether it is instead either a signature of previous AGN activity or simply an indicator of the particular set of group properties most conducive to the growth of an FR-I radio galaxy.