arXiv 1001.30182010-01-18astro-ph.CO

具有AGN反馈的模拟中的星团内恒星

Intracluster stars in simulations with AGN feedback

Ewald Puchwein, Volker Springel, Debora Sijacki, Klaus Dolag

备注：: 17 pages, 16 figures, submitted to MNRAS
DOI：: 10.1111/j.1365-2966.2010.16786.x

摘要：

我们使用一组高分辨率的流体动力学模拟的星系团，研究建立的团内光（ICL），一个有趣的和可能的重要组成部分，他们的总恒星质量。我们的集团和集群的样本包括AGN反馈，是足够高的分辨率，以准确地解决星系人口下降到最小的星系，预计将显着贡献的恒星质量预算。我们描述和测试四种不同的方法来识别模拟中的ICL，从而使我们能够评估测量的可靠性。对于所有的方法，我们始终发现一个非常显着的ICL恒星分数（~45%），超过了通常从观测推断的值。然而，我们表明，这一结果是强大的数值分辨率和积分精度，显着不敏感的恒星形成模型的变化，几乎独立的晕质量。它也几乎是不变的，当包括黑洞的增长，即使AGN反馈成功地防止过度冷却的集群，并导致一个显着改善协议的模拟集群星系人口与观测。特别是，当包含活动星系核时，中心星系的光度和它们的恒星星族年龄更加真实。根据这些发现，似乎很难构建一个模拟模型，同时匹配的集群星系的人口，并在同一时间产生一个低ICL组件。我们发现，在星系团最密集的区域，星系团内的恒星优先从z>1处落入星系团的大质量星系中剥离。令人惊讶的是，一些团内恒星也形成于冷气体云内的团内介质中，这些气体云是从下落的星系中剥离出来的。

英文摘要：

We use a set of high-resolution hydrodynamical simulations of clusters of galaxies to study the build-up of the intracluster light (ICL), an interesting and likely significant component of their total stellar mass. Our sample of groups and clusters includes AGN feedback and is of high enough resolution to accurately resolve galaxy populations down to the smallest galaxies that are expected to significantly contribute to the stellar mass budget. We describe and test four different methods to identify the ICL in simulations, thereby allowing us to assess the reliability of the measurements. For all of the methods, we consistently find a very significant ICL stellar fraction (~45%) which exceeds the values typically inferred from observations. However, we show that this result is robust with respect to numerical resolution and integration accuracy, remarkably insensitive to changes in the star formation model, and almost independent of halo mass. It is also almost invariant when black hole growth is included, even though AGN feedback successfully prevents excessive overcooling in clusters and leads to a drastically improved agreement of the simulated cluster galaxy population with observations. In particular, the luminosities of central galaxies and the ages of their stellar populations are much more realistic when including AGN. In the light of these findings, it appears challenging to construct a simulation model that simultaneously matches the cluster galaxy population and at the same time produces a low ICL component. We find that intracluster stars are preferentially stripped in a cluster's densest region from massive galaxies that fall into the cluster at z>1. Surprisingly, some of the intracluster stars also form in the intracluster medium inside cold gas clouds that are stripped out of infalling galaxies.

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