THE PAN-STARRS1 MEDIUM-DEEP SURVEY: THE ROLE OF GALAXY GROUP ENVIRONMENT IN THE STAR FORMATION RATE VERSUS STELLAR MASS RELATION AND QUIESCENT FRACTION OUT TO z ∼ 0.8
THE PAN-STARRS1 MEDIUM-DEEP SURVEY: THE ROLE OF GALAXY GROUP ENVIRONMENT IN THE STAR FORMATION RATE VERSUS STELLAR MASS RELATION AND QUIESCENT FRACTION OUT TO z ∼ 0.8
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DOI：
10.1088/0004-637x/782/1/33
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发表时间：
2013-12
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通讯作者：
Lihwai Lin;H. Jian;S. Foucaud;S. Foucaud;P. Norberg;R. Bower;S. Cole;P. Arnalte-Mur;Chin-wei Chen
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作者：
Lihwai Lin;H. Jian;S. Foucaud;S. Foucaud;P. Norberg;R. Bower;S. Cole;P. Arnalte-Mur;Chin-wei Chen
使用从 Pan-STARRS1 中深巡天 (PS1/MDS) 中抽取的大量光学选择的场和星系群样本，我们对特定恒星形成率 (SSFR) 与恒星质量 (M*) 关系以及不同环境中的静止分数与 M* 关系进行了详细分析。虽然SSFR和静止分数都强烈依赖于恒星质量，但环境也起着重要作用。使用这个大型星系样本，我们确认静止星系的比例强烈依赖于固定恒星质量下的环境，但恒星形成序列的幅度和斜率在场和星系群之间是相似的：换句话说，固定恒星质量下的SSFR-密度关系主要是由不同环境之间的恒星形成和静止比例的变化驱动的，而不是恒星形成群体的恒星形成速率的全局抑制。然而，当我们将样本限制在星团规模环境（M > 1014 M☉）时，我们发现在 4σ 置信度下，恒星形成序列的 SSFR 整体降低了 17%，而与现场对应的情况相反。在消除了场星系中静止部分的恒星质量依赖性后，发现由于群和星团中的环境猝灭而导致的静止部分的过量随着恒星质量的增加而增加，尽管需要来自完整 PS1/MDS 的更深入和更大的数据才能得出明确的结论。我们认为这些结果有利于星系合并成为星系群中运行的主要环境淬灭机制，而绞杀能够重现在星团中观察到的环境淬灭效率和恒星质量关系的观察到的趋势。我们的结果还表明，质量猝灭和环境猝灭之间的相对重要性取决于恒星质量——质量猝灭在较大质量星系产生静止星系的过程中起主导作用，而质量较小的星系主要通过环境效应猝灭，在群/星团环境中，过渡质量约为 1–2 × 1010 M☉。
Using a large optically selected sample of field and group galaxies drawn from the Pan-STARRS1 Medium-Deep Survey (PS1/MDS), we present a detailed analysis of the specific star formation rate (SSFR)—stellar mass (M*) relation, as well as the quiescent fraction versus M* relation in different environments. While both the SSFR and the quiescent fraction depend strongly on stellar mass, the environment also plays an important role. Using this large galaxy sample, we confirm that the fraction of quiescent galaxies is strongly dependent on environment at a fixed stellar mass, but that the amplitude and the slope of the star-forming sequence is similar between the field and groups: in other words, the SSFR–density relation at a fixed stellar mass is primarily driven by the change in the star-forming and quiescent fractions between different environments rather than a global suppression in the star formation rate for the star-forming population. However, when we restrict our sample to the cluster-scale environments (M > 1014 M☉), we find a global reduction in the SSFR of the star-forming sequence of 17% at 4σ confidence as opposed to its field counterpart. After removing the stellar mass dependence of the quiescent fraction seen in field galaxies, the excess in the quiescent fraction due to the environment quenching in groups and clusters is found to increase with stellar mass, although deeper and larger data from the full PS1/MDS will be required to draw firm conclusions. We argue that these results are in favor of galaxy mergers to be the primary environment quenching mechanism operating in galaxy groups whereas strangulation is able to reproduce the observed trend in the environment quenching efficiency and stellar mass relation seen in clusters. Our results also suggest that the relative importance between mass quenching and environment quenching depends on stellar mass—the mass quenching plays a dominant role in producing quiescent galaxies for more massive galaxies, while less massive galaxies are quenched mostly through the environmental effect, with the transition mass around 1–2 × 1010 M☉ in the group/cluster environment.