Evolution of the specific star formation rate function at z< 1.4 Dissecting the mass-SFR plane in COSMOS and GOODS
Evolution of the specific star formation rate function at z< 1.4 Dissecting the mass-SFR plane in COSMOS and GOODS
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DOI：
10.1051/0004-6361/201425176
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发表时间：
2014-10
影响因子：
6.5
通讯作者：
O. Ilbert;S. Arnouts;E. Floc’h;H. Aussel;H. Bethermin;P. Capak;B. Hsieh;M. Kajisawa;A. Karim-A.-Ka
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文献类型：
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作者：
O. Ilbert;S. Arnouts;E. Floc’h;H. Aussel;H. Bethermin;P. Capak;B. Hsieh;M. Kajisawa;A. Karim-A.-Ka
恒星质量（M）与星星形成速率（SFR）之间的关系表征了星星的瞬时形成是如何由星系过去的星星形成历史和暗物质结构的生长决定的。我们通过测量z = 0.2到z = 1.4的几个恒星质量仓中的特定SFR函数来解构M-SFR平面（特定SFR = SFR/M，记为sSFR）。我们的分析主要是基于一个24 μm的选择目录结合COSMOS和GOODS调查。我们估计的SFR相结合的中红外和远红外数据为20500星系。sSFR函数是在9.5 < log（M/M）< 11.5范围内的四个恒星质量仓中导出的。首先，我们证明了在研究M-SFR关系时考虑选择效应的重要性。其次，我们发现中位sSFR随红移的质量依赖性演化为sSFR和M之间。在低质量下，这种演化与宇宙学吸积速率和半解析模型（SAM）的预测一致。这一协议打破了更大的星系显示需要更全面的描述星星形成的历史，在大规模的星系。第三，我们得到sSFR函数的形状在z< 1.4时随时间不变，但取决于质量。我们观察到sSFR函数的加宽，范围从M ε = 10^（9.75）M ε时的0.28 dex到M ε = 10^（11.1）M ε时的0.46 dex。这种增加的内禀散射的M-SFR关系表明，增加多样性的恒星形成历史（SFHS）的恒星质量的增加。最后，我们发现sSFR随恒星质量的增加而逐渐下降，log _（10）（sSFR）= 0.17M <$.我们讨论了许多物理过程，如热气体晕中的气体耗尽或长期演化，这些过程可以逐渐降低sSFR并增加SFH多样性。
The relation between the stellar mass (M⋆) and the star formation rate (SFR) characterizes how the instantaneous star formation is determined by the galaxy past star formation history and by the growth of the dark matter structures. We deconstruct the M⋆-SFR plane by measuring the specific SFR functions in several stellar mass bins from z = 0.2 out to z = 1.4 (specific SFR = SFR/M⋆, noted sSFR). Our analysis is primary based on a 24 μm selected catalogue combining the COSMOS and GOODS surveys. We estimate the SFR by combining mid- and far-infrared data for 20500 galaxies. The sSFR functions are derived in four stellar mass bins within the range 9.5 < log (M⋆ /M⊙) < 11.5. First, we demonstrate the importance of taking into account selection effects when studying the M⋆-SFR relation. Secondly, we find a mass-dependent evolution of the median sSFR with redshift varying as sSFR ∝ (1 + z)^b, with b increasing from b = 2.88^(±0.12) to b = 3.78^(± 0.60) between M⋆ = 10^(9.75) M⊙ and M⋆ = 10^(11.1) M⊙, respectively. At low masses, this evolution is consistent with the cosmological accretion rate and predictions from semi-analytical models (SAM). This agreement breaks down for more massive galaxies showing the need for a more comprehensive description of the star formation history in massive galaxies. Third, we obtain that the shape of the sSFR function is invariant with time at z< 1.4 but depends on the mass. We observe a broadening of the sSFR function ranging from 0.28 dex at M⋆ = 10^(9.75) M⊙ to 0.46 dex at M⋆ = 10^(11.1) M⊙. Such increase in the intrinsic scatter of the M⋆-SFR relation suggests an increasing diversity ofstar formation histories (SFHs) as the stellar mass increases. Finally, we find a gradual decline of the sSFR with stellar mass as log _(10)(sSFR) ∝ −0.17M⋆. We discuss the numerous physical processes, as gas exhaustion in hot gas halos or secular evolution, which can gradually reduce the sSFR and increase the SFH diversity.