Evolution of the clustering of photometrically selected SDSS galaxies
Evolution of the clustering of photometrically selected SDSS galaxies
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光度选择的 SDSS 星系簇的演化
DOI：
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发表时间：
2010
期刊：
影响因子：
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通讯作者：
R. Brunner
中科院分区：
文献类型：
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作者：
A. Ross;W. Percival;R. Brunner
我们测量了斯隆数字巡天（SDSS）星系的角自相关函数ω（θ），这些星系的光度红移为0.1 < z < 0.4，r波段绝对星等Mr < −21.2。为了研究SDSS星系的演化，我们将这些星系分成5个宽度为0.1的重叠红移壳层，并测量每个子样本中的ω（θ）。我们发现，随着红移的增加，偏置大大增加，这比人们对被动演化样本的预期要多得多。我们使用晕圈模型分析来确定每个子样本的最佳拟合晕圈占据分布（HOD），最佳拟合模型使我们能够从物理上解释偏倚的变化。为了正确解释我们的最佳拟合HOD，我们将每个晕质量转换为z= 0的被动演化偏置（bo），从而能够直接比较不同红移下的最佳拟合HOD。我们发现，当红移减小时，容纳星系所需的最小晕bo也减小，这表明在我们的红移范围内，Mr <-21.2的星系在HOD的低质量端形成晕。我们使用最佳拟合的HOD来确定占据数的变化除以晕质量的变化，并保持恒定的bo，ΔN/ΔM（bo），我们发现在bo = 0.9处有一个尖锐的峰值，对应于平均晕质量为1012 h−1 M。因此，我们提出了以下的假设：随着宇宙的演化，Mr < −21.2的星系的偏差会减小，因为这些星系形成质量为的晕（与红移无关），这些晕的偏差会随着宇宙的演化而自然减小。
We measure the angular auto-correlation functions, ω(θ), of Sloan Digital Sky Survey (SDSS) galaxies selected to have photometric redshifts 0.1 < z < 0.4 and absolute r-band magnitudes Mr < −21.2. We split these galaxies into five overlapping redshift shells of width 0.1 and measure ω(θ) in each subsample in order to investigate the evolution of SDSS galaxies. We find that the bias increases substantially with redshift – much more so than one would expect for a passively evolving sample. We use halo-model analysis to determine the best-fitting halo-occupation-distribution (HOD) for each subsample, and the best-fitting models allow us to interpret the change in bias physically. In order to properly interpret our best-fitting HODs, we convert each halo mass to its z= 0 passively evolved bias (bo), enabling a direct comparison of the best-fitting HODs at different redshifts. We find that the minimum halo bo required to host a galaxy decreases as the redshift decreases, suggesting that galaxies with Mr < −21.2 are forming in haloes at the low-mass end of the HODs over our redshift range. We use the best-fitting HODs to determine the change in occupation number divided by the change in mass of haloes with constant bo, ΔN/ΔM (bo), and we find a sharp peak at bo∼ 0.9– corresponding to an average halo mass of ∼1012 h−1 M⊙. We thus present the following scenario: the bias of galaxies with Mr < −21.2 decreases as the Universe evolves because these galaxies form in haloes of mass ∼1012 h−1 M⊙ (independent of redshift), and the bias of these haloes naturally decreases as the Universe evolves.