The Cluster Mgas-TX Relation: Evidence for a High Level of Preheating
The Cluster Mgas-TX Relation: Evidence for a High Level of Preheating
复制标题
簇 Mgas-TX 关系：高水平预热的证据
DOI：
10.1086/340663
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发表时间：
2002
期刊：
影响因子：
--
通讯作者：
M. Balogh
中科院分区：
文献类型：
--
作者：
I. McCarthy;A. Babul;M. Balogh
最近的X射线观测已经被用来证明，团簇气体的质量-温度关系比从数值模拟中得出的理论自相似预测更陡峭，该数值模拟考虑了团簇气体单独通过重力和冲击加热的影响的演化。一个可能的解释是，气体质量分数在不同温度的星系团中并不恒定，这是通常假设的。然而，在观测上，没有令人信服的证据表明气体质量分数的变化，特别是在热星团的情况下。寻求另一种物理解释所观察到的趋势，我们调查的作用，在集群气体的质量-温度关系的预热的集群内介质的一些任意源的集群与发射加权平均温度的TX <$3千电子伏。利用身体动机，分析模型开发的2002年由Bethesda和同事，我们发现，预热确实会导致一个陡峭的关系。这与以往的理论研究是一致的。然而，在这些研究明显的冲突，我们认为，一个“高”水平的熵注入需要匹配的意见。特别是，需要300 keV cm 2的熵底。我们还提出了一种新的检验方法，即在不同的固定半径范围内研究这种关系。这使得人们可以间接探测团簇的密度分布，因为它对不同温度的团簇的维里半径的不同部分进行采样。该测试还证实，需要高水平的预热来匹配观察结果。
Recent X-ray observations have been used to demonstrate that the cluster gas mass-temperature relation is steeper than theoretical self-similar predictions drawn from numerical simulations that consider the evolution of the cluster gas through the effects of gravity and shock heating alone. One possible explanation for this is that the gas mass fraction is not constant across clusters of different temperature, as is usually assumed. Observationally, however, there is no compelling evidence for gas mass fraction variation, especially in the case of hot clusters. Seeking an alternative physical explanation for the observed trends, we investigate the role in the cluster gas mass-temperature relation of the preheating of the intracluster medium by some arbitrary source for clusters with emission-weighted mean temperatures of TX ≳ 3 keV. Making use of the physically motivated, analytic model developed in 2002 by Babul and coworkers, we find that preheating does, indeed, lead to a steeper relation. This is in agreement with previous theoretical studies on the relation. However, in apparent conflict with these studies, we argue that a "high" level of entropy injection is required to match observations. In particular, an entropy floor of ≳300 keV cm2 is required. We also present a new test, namely, the study of the relation within different fixed radii. This allows one to indirectly probe the density profiles of clusters, since it samples different fractions of the virial radius for clusters of different temperature. This test also confirms that a high level of preheating is required to match observations.