论文标题
低质量组环境对卷乳媒介物金属性没有实质性影响
Low Mass Group Environments have no Substantial Impact on the Circumgalactic Medium Metallicity
论文作者
论文摘要
我们探讨了环境如何使用13个低质量星系组（2-5个星系）在$ \ langle z_ {abs} \ rangle = 0.25 $的情况下，如何影响环境培养基（CGM）的金属性（CGM）。使用来自HST/COS的Quasar光谱以及Keck/Hires或VLT/Uves的Quasar光谱，我们测量了CGM吸收系的柱密度或确定限制的柱。我们使用Markov链蒙特卡洛（Monte Carlo）方法，用云朵的方法来估计凉爽的金属（$ t \ sim10^4 $ k）CGM气体内部的CGM气体，并将它们与47个孤立星系的CGM金属性进行比较。组和孤立的CGM金属均范围很广（$ -2 <$ [Si/h] $ <0 $），其中平均组（$ -0.54 \ pm0.22 $）和隔离（$ -0.77 \ pm0.14 $）CGM金属相似。组和孤立的环境具有{\ hi}列密度作为影响参数的函数的相似分布。但是，与孤立的星系相反，我们没有发现{\ hi}柱密度与最近的组星系冲击参数之间的抗相关性。我们还将这些组除以成员的发光比（即星系 - 半纳克斯和星系 - 划线组）。尽管它们的平均金属性没有显着差异，但与星系 - 半差异组相比，样本量适中的增加应该使人们可以从统计学上识别Galaxy-Dwarf组的CGM金属性更高。我们得出的结论是，在此阶段，这两种环境影响在CGM的金属性中都没有发挥重要作用，并且期望这可能只有在星系强烈相互作用或合并时发生，或者某些孤立的星系由于过去相互作用而具有较高的CGM金属性。因此，环境似乎不是CGM金属双峰性的原因。
We explore how environment affects the metallicity of the circumgalactic medium (CGM) using 13 low mass galaxy groups (2-5 galaxies) at $\langle z_{abs}\rangle=0.25$ identified near background quasars. Using quasar spectra from HST/COS and from Keck/HIRES or VLT/UVES we measure column densities of, or determine limits on, CGM absorption lines. We use a Markov chain Monte Carlo approach with Cloudy to estimate metallicities of cool ($T\sim10^4$K) CGM gas within groups and compare them to CGM metallicities of 47 isolated galaxies. Both group and isolated CGM metallicities span a wide range ($-2<$[Si/H]$<0$), where the mean group ($-0.54\pm0.22$) and isolated ($-0.77\pm0.14$) CGM metallicities are similar. Group and isolated environments have similar distributions of {\HI} column densities as a function of impact parameter. However, contrary to isolated galaxies, we do not find an anti-correlation between {\HI} column density and the nearest group galaxy impact parameter. We additionally divided the groups by member luminosity ratios (i.e., galaxy-galaxy and galaxy-dwarf groups). While there was no significant difference in their mean metallicities, a modest increase in sample size should allow one to statistically identify a higher CGM metallicity in galaxy-dwarf groups compared to galaxy-galaxy groups. We conclude that either environmental effects have not played an important role in the metallicity of the CGM at this stage and expect that this may only occur when galaxies are strongly interacting or merging, or that some isolated galaxies have higher CGM metallicities due to past interactions. Thus, environment does not seem to be the cause of the CGM metallicity bimodality.
