The dependence of galaxy properties on the large-scale tidal environment
The dependence of galaxy properties on the large-scale tidal environment
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DOI：
10.1093/mnras/stt141
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发表时间：
2013-04
影响因子：
4.8
通讯作者：
H. Yan;Z. Fan;S. White
中科院分区：
文献类型：
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作者：
H. Yan;Z. Fan;S. White
利用Sloan数字巡天数据第7版（SDSS DR 7）中的有限体积样本，测量了星系的潮汐环境，用平滑后的星系空间数密度1+ δ和由此导出的位场椭圆率e来表征，研究了星系的颜色、Dn 4000、浓度和大小除了依赖于1+ δ外，是否与e相关.我们发现，存在一个过渡平滑尺度，在该尺度上，与e的相关性/反相关性反转。这种跃迁尺度可以用一个体积有限的样本中星系到第三近邻星系的距离来表示，样本中的Mr <− 20，其分布峰值在1.22 h− 1 Mpc。我们进一步证明，这个尺度对应于星系颜色与环境密度1+ δ之间的相关性最强的地方。对于这种最佳平滑R 0没有额外的相关性与e观察。在其他平滑尺度Rs上，潮汐椭圆率e的明显依赖性可视为几何效应，它是由（1+ δ o）和e（Rs）之间的互相关引起的。我们进行了相同的分析数值模拟与半分析模型（SAM）的星系形成。星系性质的e依赖性表现出类似的行为，在SDSS，虽然颜色密度相关性显着更强的SAM。SAM中的“最佳自适应平滑尺度”也与星系第三近邻的距离密切相关，其特征值与SDSS一致，尽管略小于SDSS。
Using volume-limited samples drawn from the Sloan Digital Sky Survey Data Release 7 (SDSS DR7), we measure the tidal environment of galaxies, which we characterize by the smoothed spatial number density 1+ δ of galaxies and the ellipticity e of the potential field derived from it. We investigate whether galaxy colour, D n 4000, concentration and size correlate with e, in addition to depending on 1+ δ. We find that there exists a transition smoothing scale at which correlations/anti-correlations with e reverse. This transition scale is well represented by the distance to the third nearest neighbour of a galaxy in a volume-limited sample with M r<− 20, which has a distribution peaked at∼ 2 h− 1 Mpc. We further demonstrate that this scale corresponds to that where the correlation between the colour of galaxies and environmental density 1+ δ is the strongest. For this optimal smoothing R 0 no additional correlations with e are observed. The apparent dependence on tidal ellipticity e at other smoothing scales R s can be viewed as a geometric effect, arising from the cross-correlation between (1+ δ o) and e (R s). We perform the same analysis on numerical simulations with semi-analytical modelling (SAM) of galaxy formation. The e dependence of the galaxy properties shows similar behaviour to that in the SDSS, although the colour–density correlation is significantly stronger in the SAM. The ‘optimal adaptive smoothing scale’in the SAM is also closely related to the distance to the third nearest neighbour of a galaxy, and its characteristic value is consistent with, albeit slightly smaller than for SDSS.