恒星形成星系化学性质的环境依赖性
The environmental dependence of the chemical properties of star-forming galaxies
摘要：
我们使用斯隆数字巡天第四次数据发布的37866个恒星形成星系的0.040 < z < 0.085样本来研究气相化学性质对恒星质量和环境的依赖性。根据到第四和第五近邻的预计距离确定的当地密度被用作环境指标。考虑到从空隙，即，log Sigma <-0.8，到星系团的外围，即，log Sigma =~ 0.8，我们发现星系恒星质量和气相氧丰度之间的关系没有依赖性，以及其相关的散射，局部星系密度。然而，星系中的恒星形成气体在密度较高的环境中，在固定的恒星质量下，化学富集水平略有增加。与低密度环境中类似恒星质量的星系相比，对于大质量星系，它们会增强几个百分点，对于恒星质量< 10^{9.5}太阳质量的星系，它们会增强约20%。这些结果意味着恒星形成星系的演化主要是由它们的内在属性驱动的，并且在很大范围内的局部星系密度在很大程度上与它们的环境无关。
英文摘要：
We use a 0.040 < z < 0.085 sample of 37866 star-forming galaxies from the Fourth Data Release of the Sloan Digital Sky Survey to investigate the dependence of gas-phase chemical properties on stellar mass and environment. The local density, determined from the projected distances to the fourth and fifth nearest neighbours, is used as an environment indicator. Considering environments ranging from voids, i.e., log Sigma < -0.8, to the periphery of galaxy clusters, i.e., log Sigma =~ 0.8, we find no dependence of the relationship between galaxy stellar mass and gas-phase oxygen abundance, along with its associated scatter, on local galaxy density. However, the star-forming gas in galaxies shows a marginal increase in the chemical enrichment level at a fixed stellar mass in denser environments. Compared with galaxies of similar stellar mass in low density environments, they are enhanced by a few per cent for massive galaxies to about 20 per cent for galaxies with stellar masses < 10^{9.5} solar masses. These results imply that the evolution of star-forming galaxies is driven primarily by their intrinsic properties and is largely independent of their environment over a large range of local galaxy density.
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