Clustering dark energy and halo abundances
Clustering dark energy and halo abundances
复制标题
聚集暗能量和光环丰度
DOI：
10.1088/1475-7516/2017/11/048
复制
发表时间：
2017
影响因子：
6.4
通讯作者：
V. Marra
中科院分区：
文献类型：
--
作者：
R. C. Batista;V. Marra
在标准范式中，暗能量被视为推动宇宙加速膨胀的均质流体，与星系和星系团等坍塌物体的质量无关。星系团的丰度--通过各种渠道测量--已被广泛用于限制功率谱的正常化：这是一个重要的探测器，因为它允许我们测试标准的Λ清洁发展机制模型是否真的能准确地描述数十亿年来结构的演变。因此，相当重要的是，普朗克卫星通过Sunyaev-Zel‘dovich效应探测到的星团比预期的要少，根据主要的CMB各向异性。最简单的概括之一就是考虑允许暗能量聚集的模型，也就是允许暗能量的声速变化。然而，在这种情况下，计算星系团丰度的标准方法需要调整，以考虑暗能量的贡献。特别是，我们研究了暗能量聚集的情况-一种可以忽略音速的暗能量流体-与红移相关的状态方程。我们仔细研究了在这种情况下如何修改晕质量函数，突出了以前在文献中没有考虑到的修正。我们讨论了增长函数、崩塌阈值、病毒化密度的修改以及崩塌和质量函数归一化的共同尺度的变化。我们的结果表明，星系团暗能量可以在10%-30%的水平上影响晕丰度，这取决于晕质量，并且星系团的计数在单位红移时被修正了约30%。
Within the standard paradigm, dark energy is taken as a homogeneous fluid that drives the accelerated expansion of the universe and does not contribute to the mass of collapsed objects such as galaxies and galaxy clusters. The abundance of galaxy clusters—measured through a variety of channels—has been extensively used to constrain the normalization of the power spectrum: it is an important probe as it allows us to test if the standard ΛCDM model can indeed accurately describe the evolution of structures across billions of years. It is then quite significant that the Planck satellite has detected, via the Sunyaev-Zel'dovich effect, less clusters than expected according to the primary CMB anisotropies. One of the simplest generalizations that could reconcile these observations is to consider models in which dark energy is allowed to cluster, i.e., allowing its sound speed to vary. In this case, however, the standard methods to compute the abundance of galaxy clusters need to be adapted to account for the contributions of dark energy. In particular, we examine the case of clustering dark energy—a dark energy fluid with negligible sound speed—with a redshift-dependent equation of state. We carefully study how the halo mass function is modified in this scenario, highlighting corrections that have not been considered before in the literature. We address modifications in the growth function, collapse threshold, virialization densities and also changes in the comoving scale of collapse and mass function normalization. Our results show that clustering dark energy can impact halo abundances at the level of 10%–30%, depending on the halo mass, and that cluster counts are modified by about 30% at a redshift of unity.