Halpha3：HI从ALFALFA中选出的星系的Halpha成像巡天。II。室女星系团及其周围星系的恒星形成性质
Halpha3: an Halpha imaging survey of HI selected galaxies from ALFALFA. II. The star formation properties of galaxies in the Virgo cluster and surroundings
摘要：
我们对Halph 3进行了分析，Halph 3是对本超星系团中HI Arecibo ALFALFA巡天中选出的409个星系进行的Halph成像巡天，其中包括室女星系团。我们探讨恒星质量，HI质量和当前，大规模的SFR附近的星系在室女星系团之间的关系，我们比较它们与孤立的星系在本地超星系团，解开环境中塑造的恒星形成属性的星系在本宇宙学时代的作用。我们调查原子中性气体和新形成的恒星在不同的环境中，在许多形态类型之间的关系，并在广泛的恒星质量采用更新的校准HI不足参数。研究了本超星系团中晚型星系的平均性质，发现在本超星系团密度增加（或与M87的投影角距减小）的情况下，星系的HI含量和平均比恒星形成率显著降低，同时它们的恒星星族逐渐变红。恒星形成的逐渐淬火发生在由外向内，与冲压压力模型的预测一致。一旦作为一个整体来考虑，室女星系团在从星系中移除中性氢方面是有效的，这种扰动足以明显地减少其整个星系群的SFR。假设HI消融的时间尺度为200 - 300 Myr，根据现有的HI富集的晚型系统的数量，估计室女星系团目前的坍缩速率为每Gyr 300 - 400个星系。如果下落过程一直以恒定速率作用，这将意味着室女星系团大约在2 Gyr前形成，这与室女星系团处于动力学演化的年轻状态的想法一致。
英文摘要：
We present the analysis of Halpha3, an Halpha imaging survey of 409 galaxies selected from the HI Arecibo ALFALFA Survey in the Local Supercluster, including the Virgo cluster. We explore the relations between the stellar mass, the HI mass and the current, massive SFR of nearby galaxies in the Virgo cluster and we compare them with those of isolated galaxies in the Local Supercluster, disentangling the role of the environment in shaping the star formation properties of galaxies at the present cosmological epoch. We investigate the relationships between atomic neutral gas and newly formed stars in different environments, across many morphological types, and over a wide range of stellar masses adopting an updated calibration of the HI deficiency parameter. Studying the mean properties of late-type galaxies in the Local Supercluster, we find that galaxies in increasing local galaxy density conditions (or decreasing projected angular separation from M87) show a significant decrease in the HI content and in the mean specific star formation rate, along with a progressive reddening of their stellar populations. The gradual quenching of the star formation occurs outside-in, consistently with the predictions of the ram pressure model. Once considered as a whole, the Virgo cluster is effective in removing neutral hydrogen from galaxies, and this perturbation is strong enough to appreciably reduce the SFR of its entire galaxy population. An estimate of the present infall rate of 300-400 galaxies per Gyr in the Virgo cluster is obtained from the number of existing HI-rich late-type systems, assuming 200-300 Myr as the time scale for HI ablation. If the infall process has been acting at constant rate this would imply that the Virgo cluster has formed approximately 2 Gyr ago, consistently with the idea that Virgo is in a young state of dynamical evolution.
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