The Origin of Star Formation Gradients in Rich Galaxy Clusters
The Origin of Star Formation Gradients in Rich Galaxy Clusters
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DOI：
10.1086/309323
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发表时间：
2000-04
期刊：
影响因子：
--
通讯作者：
M. Balogh;J. Navarro;S. Morris
中科院分区：
文献类型：
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作者：
M. Balogh;J. Navarro;S. Morris
我们在一个简单模型的背景下研究了富星系团中星系的恒星形成率和颜色的以星系团为中心的梯度的起源，在该模型中，星系团是通过不断吸积场星系而形成的。该模型假设，在星系进入星系团后，它们的恒星形成率会在几十亿年的时间尺度上下降，这是场中盘状星系典型的气体消耗时间尺度。如果潮汐力和冲压剥离了通常在哈勃时间内为螺旋星系中的恒星形成提供燃料的气态包层，那么这种行为是可以预期的。将这些时间尺度与从ΛCDM宇宙中星系团形成的N体模拟得出的质量吸积历史相结合，我们重现了在星系团和场星系的颜色分布中观察到的系统性差异，以及星系团中恒星形成的强烈抑制及其对以星系团为中心的半径的依赖性。模拟还表明，在星系团的维里半径之外的很大一部分星系可能在过去处于星系团的主体内，这一结果自然地解释了为什么星系团外围（远至2倍维里半径）的恒星形成相对于场是系统性地受到抑制。如果我们假设剥离发生在较低质量的系统内，在星系被吸积到星系团主体之前，那么与星系团维里半径之外的数据的一致性也会得到改善。我们得出结论，星系团中星系的恒星形成率主要取决于它们被吸积到巨大的维里化系统后所经过的时间，并且恒星形成的停止可能是在几十亿年的时间内逐渐发生的。
We examine the origin of clustercentric gradients in the star formation rates and colors of rich cluster galaxies within the context of a simple model where clusters are built through the ongoing accretion of field galaxies. The model assumes that after galaxies enter the cluster their star formation rates decline on a timescale of a few gigayears, the typical gas consumption timescale of disk galaxies in the field. Such behavior might be expected if tides and ram pressure strip off the gaseous envelopes that normally fuel star formation in spirals over a Hubble time. Combining these timescales with mass accretion histories derived from N-body simulations of cluster formation in a ΛCDM universe, we reproduce the systematic differences observed in the color distribution of cluster and field galaxies, as well as the strong suppression of star formation in cluster galaxies and its dependence on clustercentric radius. The simulations also indicate that a significant fraction of galaxies beyond the virial radius of the cluster may have been within the main body of the cluster in the past, a result that explains naturally why star formation in the outskirts of clusters (and as far out as 2 virial radii) is systematically suppressed relative to the field. The agreement with the data beyond the cluster virial radius is also improved if we assume that stripping happens within lower mass systems, before the galaxy is accreted into the main body of the cluster. We conclude that the star formation rates of cluster galaxies depend primarily on the time elapsed since their accretion onto massive virialized systems and that the cessation of star formation may have taken place gradually over a few gigayears.