关于Hickson紧群中的分子气含量和SFR：增强还是缺乏？
On the molecular gas content and SFR in Hickson Compact Groups: enhanced or deficient?
摘要：
本文研究了希克森致密星系群（HCGs）极端环境对星系气体分子质量\mhtwo和恒星形成率（SFR）的影响，并将其作为星系群氢原子含量和演化阶段的函数。我们选择了一个红移有限（D $<$ 100 Mpc）的88个星系的样本在20个HCG可用的原子氢（HI）VLA地图，涵盖了广泛的HI缺陷和演化阶段的群体，并包含至少一个旋涡星系。我们从IRAS数据中推导出远红外（FIR）光度（\lfir），并将其用作SFR的示踪剂。我们计算了HI质量、\lfir和\mhtwo缺陷。旋涡星系的\lfir和\mhtwo的平均亏损接近于0，表明它们的平均SFR和分子气体含量与孤立星系相似。然而，有迹象表明，在螺旋星系的\mhtwo \（$\sim$ 50%）在HCG可以被解释为一个增强的分子气体含量或作为一个更高的浓度\mhtwo向中心相比，在较低密度的环境中的星系。相比之下，在HCG的螺旋星系的平均\mhi是只有12%的预期值。对于\mhtwo \或\mhi \亏损较大的星系，比恒星形成率（sSFR= SFR/恒星质量）往往较低。对于恒星形成效率（SFE=SFR/ \mhtwo），没有看到这种趋势。我们发现了初步迹象的增强\mhtwo \在螺旋星系的HCG在早期的演化阶段和减少在后期阶段。我们认为，这可能是由于增强的转换从原子到分子气体由于正在进行的潮汐相互作用在早期的进化阶段，随后由HI剥离和减少的分子气体含量，因为缺乏补充。
英文摘要：
We study the effect of the extreme environment in Hickson Compact groups (HCGs) on the molecular gas mass, \mhtwo, and the star formation rate (SFR) of galaxies as a function of atomic hydrogen (HI) content and evolutionary phase of the group. We have selected a redshift limited (D$<$100 Mpc) sample of 88 galaxies in 20 HCGs with available atomic hydrogen (HI) VLA maps, covering a wide range of HI deficiencies and evolutionary phases of the groups, and containing at least one spiral galaxy. We derived the far-infrared (FIR) luminosity (\lfir) from IRAS data and used it as a tracer of the SFR. We calculated the HI mass, \lfir and \mhtwo deficiencies. The mean deficiencies of \lfir and \mhtwo of spiral galaxies in HCGs are close to 0, indicating that their average SFR and molecular gas content are similar to those of isolated galaxies. However, there are indications of an excess in \mhtwo\($\sim$ 50%) in spiral galaxies in HCGs which can be interpreted as either an enhanced molecular gas content or as a higher concentration of \mhtwo towards the center in comparison to galaxies in lower density environments. In contrast, the mean \mhi of spiral galaxies in HCGs is only 12% of the expected value. The specific star formation rate (sSFR= SFR/stellar mass) tends to be lower for galaxies with a higher \mhtwo\ or \mhi\ deficiency. This trend is not seen for the star formation efficiency (SFE=SFR/\mhtwo). We found tentative indications for an enhancement of \mhtwo\ in spiral galaxies in HCGs in an early evolutionary phase and a decrease in later phases. We suggest that this might be due to an enhancement of the conversion from atomic to molecular gas due to on-going tidal interactions in an early evolutionary phase, followed by HI stripping and a decrease of the molecular gas content because of lack of replenishment.
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