Stacked phase-space density of galaxies around massive clusters: comparison of dynamical and lensing masses
Stacked phase-space density of galaxies around massive clusters: comparison of dynamical and lensing masses
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DOI：
10.1093/mnras/stab1961
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发表时间：
2021-01
影响因子：
4.8
通讯作者：
M. Shirasaki;E. Egami;N. Okabe;S. Miyazaki
中科院分区：
文献类型：
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作者：
M. Shirasaki;E. Egami;N. Okabe;S. Miyazaki
我们提出的测量平均直方图的视线速度对星系和星系团。由于直方图可以在不同的星系团间隔处测量，因此这种可观察到的结果通常被称为堆叠相空间密度。我们基于晕圈模型的方法来建立叠加相空间密度，使该模型可以应用于真实的星系和星系团样本。我们通过使用具有已知弱透镜质量的大质量星系团的实际样本和星系团周围星系的光谱观测来检验我们的模型。用我们的模型进行似然分析使我们能够推断出在大质量星系团中观测到的星系的球对称速度色散。我们发现，在68%的置信水平下，透镜质量为$1.1\乘以10^{15}\，h^{-1}\,{\rm M}_{\odot}$的星系团周围的星系的速度色散为$1180^{+83}_{-70}\,\math {km\,s^{-1}}$。我们的约束证实了我们样本中星系速度色散与宿主星团质量之间的关系与广义相对论下仅暗物质n体模拟的预测一致。假设星系团中的泊松方程可以被一个有效的重力常数Geff改变，我们对速度色散的测量可以在大约2.5亿年前的几个Mpc的长度尺度上给出一个严格的约束：$0.88 \lt G_\ mathm {eff}/G_\ mathm {N} \lt 1.29\, (68{{\ \rm \ %}})$，其中GN是牛顿常数。
We present a measurement of average histograms of line-of-sight velocities over pairs of galaxies and galaxy clusters. Since the histogram can be measured at different galaxy-cluster separations, this observable is commonly referred to as the stacked phase-space density. We formulate the stacked phase-space density based on a halo-model approach so that the model can be applied to real samples of galaxies and clusters. We examine our model by using an actual sample of massive clusters with known weak-lensing masses and spectroscopic observations of galaxies around the clusters. A likelihood analysis with our model enables us to infer the spherical-symmetric velocity dispersion of observed galaxies in massive clusters. We find the velocity dispersion of galaxies surrounding clusters with their lensing masses of $1.1\times 10^{15}\, h^{-1}\,{\rm M}_{\odot }$ to be $1180^{+83}_{-70}\, \mathrm{km\,s^{-1}}$ at the 68 per cent confidence level. Our constraint confirms that the relation between the galaxy velocity dispersion and the host cluster mass in our sample is consistent with the prediction in dark-matter-only N-body simulations under General Relativity. Assuming that the Poisson equation in clusters can be altered by an effective gravitational constant of Geff, our measurement of the velocity dispersion can place a tight constraint of $0.88 \lt G_\mathrm{eff}/G_\mathrm{N} \lt 1.29\, (68{{\ \rm per\ cent}})$ at length-scales of a few Mpc about 2.5 Giga years ago, where GN is the Newton’s constant.