Gas expulsion by quasar-driven winds as a solution to the overcooling problem in galaxy groups and clusters
Gas expulsion by quasar-driven winds as a solution to the overcooling problem in galaxy groups and clusters
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DOI：
10.1111/j.1365-2966.2010.18033.x
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发表时间：
2010-08
影响因子：
4.8
通讯作者：
I. McCarthy;J. Schaye;R. Bower;T. Ponman;C. Booth;C. D. Vecchia;V. Springel
中科院分区：
文献类型：
--
作者：
I. McCarthy;J. Schaye;R. Bower;T. Ponman;C. Booth;C. D. Vecchia;V. Springel
星系群不是大质量星系团的缩小版本-星系群中的热气体（称为群内介质，简称IGRM）平均来说比星系团内介质密度小，这意味着一个或多个非引力过程（例如，辐射冷却、星星形成和/或反馈）对群体具有相对较大的影响。在本研究中，我们比较了一些宇宙学流体动力学模拟，这些模拟构成了超大模拟项目的一部分，以隔离和量化超新星（SNe）和活动星系核（AGN）对气体的冷却和反馈的影响。这是通过比较拉格朗日热历史的气体在不同的运行，这都是从相同的初始条件。虽然辐射冷却，星星形成和SN反馈都是必要的成分，只有运行，也包括AGN反馈能够成功地再现集团和低质量集群的光学和X射线特性。我们分离如何，何时，以及究竟是什么气体被AGN加热。有趣的是，我们发现构成今天IGRM的气体是没有被活动星系核强烈加热的气体。相反，现今星系群中气体的低中位密度/高中位熵是通过从高红移的低质量祖星系（主要是2 . z . 4）。这对应于超大质量黑洞吸积大部分质量的时代，通常以接近爱丁顿极限的速度（即，当黑洞处于“类星体模式”时）。
Galaxy groups are not scaled down versions of massive galaxy clusters - the hot gas in groups (known as the intragroup medium, IGrM for short) is, on average, less dense than the intracluster medium, implying that one or more non-gravitational processes (e.g., radiative cooling, star formation, and/or feedback) has had a relatively larger effect on groups. In the present study, we compare a number of cosmological hydrodynamic simulations that form part of the OverWhelmingly Large Simulations project to isolate and quantify the effects of cooling and feedback from supernovae (SNe) and active galactic nuclei (AGN) on the gas. This is achieved by comparing Lagrangian thermal histories of the gas in the different runs, which were all started from identical initial conditions. While radiative cooling, star formation, and SN feedback are all necessary ingredients, only runs that also include AGN feedback are able to successfully reproduce the optical and X-ray properties of groups and low-mass clusters. We isolate how, when, and exactly what gas is heated by AGN. Interestingly, we find that the gas that constitutes the present-day IGrM is that which was not strongly heated by AGN. Instead, the low median density/high median entropy of the gas in present-day groups is achieved by the ejection of lower entropy gas from low-mass progenitor galaxies at high redshift (primarily 2 . z . 4). This corresponds to the epoch when supermassive black holes accreted most of their mass, typically at a rate that is close to the Eddington limit (i.e., when the black holes are in a ‘quasar mode’).