Galaxy evolution from strong‐lensing statistics: the differential evolution of the velocity dispersion function in concord with the Λ cold dark matter paradigm
Galaxy evolution from strong‐lensing statistics: the differential evolution of the velocity dispersion function in concord with the Λ cold dark matter paradigm
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DOI：
10.1111/j.1365-2966.2009.16073.x
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发表时间：
2008-11
影响因子：
4.8
通讯作者：
K. Chae
中科院分区：
文献类型：
--
作者：
K. Chae
基于测量和蒙特卡罗实现的星系局部速度色散函数(VDF)以及来自宇宙透镜全天巡天、PMN-σ河外透镜巡天和哈勃太空望远镜快照观测的30个强透镜源的修正统计性质，我们研究了σ≳为95 km的S-1星系从z=1到0的演化。我们假设一个星系的总(亮+暗)质量分布在0<；z≤1的光学区是等温的，正如透镜星系的质量模型所表明的那样。这项研究是第一次研究VDF形状以及整体数密度的演变。除早期VDF外，还首次研究了全型VDF和晚型VDF的演化。对于VDF的演化行为，我们发现：(1)σ≳为200 km的大质量(主要是早型)星系的数密度随速度色散越大而演化越差；(2)中低质量早型星系(95 Km S-1≲σ≲200 Km S-1)的数密度几乎不变；(3)由蒙特卡罗实现的圆速度函数转化而成的晚期VDF与其形状不演化或积分数密度一致，与星系观测结果一致。VDF的这些演化行为与N体模拟得到的暗晕质量函数(DMF)和最近的星系形成半解析模型预测的恒星质量函数(SMF)惊人地相似。有趣的是，VDF演化似乎与许多星系调查所获得的“恒星质量缩小”演化有本质上的不同。本文根据最新的理论和观测结果，对DMF、VDF和SMF的共同演化进行了详细的定量研究。我们考虑了透镜分析中几种可能的系统误差，发现它们不太可能改变结论。
We study galaxy evolution from z = 1 to 0 as a function of velocity dispersion σ for galaxies with σ ≳ 95 km s -1 based on the measured and Monte Carlo realized local velocity dispersion functions (VDFs) of galaxies and the revised statistical properties of 30 strongly lensed sources from the Cosmic Lens All-Sky Survey, the PMN-NVSS Extragalactic Lens Survey and the Hubble Space Telescope Snapshot survey. We assume that the total (luminous plus dark) mass profile of a galaxy is isothermal in the optical region for 0 < z ≤ 1 as suggested by mass modelling of lensing galaxies. This study is the first to investigate the evolution of the VDF shape as well as the overall number density. It is also the first to study the evolution of the total and the late-type VDFs in addition to the early-type VDF. For the evolutionary behaviours of the VDFs, we find that: (1) the number density of massive (mostly early-type) galaxies with σ ≳ 200 km s -1 evolves differentially in the way that the number density evolution is greater at a higher velocity dispersion; (2) the number density of intermediate- and low-mass early-type galaxies (95 km s -1 ≲ σ ≲ 200 km s -1 ) is nearly constant and (3) the late-type VDF transformed from the Monte Carlo realized circular velocity function is consistent with no evolution in its shape or integrated number density consistent with galaxy survey results. These evolutionary behaviours of the VDFs are strikingly similar to those of the dark halo mass function (DMF) from N-body simulations and the stellar mass function (SMF) predicted by recent semi-analytic models of galaxy formation under the current A cold dark matter hierarchical structure formation paradigm. Interestingly, the VDF evolutions appear to be qualitatively different from 'stellar-mass-downsizing' evolutions obtained by many galaxy surveys. The co-evolution of the DMF, the VDF and the SMF is investigated in quantitative detail based on up-to-date theoretical and observational results in a following paper. We consider several possible systematic errors for the lensing analysis and find that they are not likely to alter the conclusions.