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arXiv 1202.0290astro-ph.CO
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z < 2时星暴和正常星系对红外光度函数的贡献

The contribution of starbursts and normal galaxies to infrared luminosity functions at z < 2

Mark T. Sargent, M. Béthermin, E. Daddi, D. Elbaz

摘要:

提出了一种无参数的方法来预测红移z < 2时红外(IR)光度函数(LF)的形状。它不需要调谐,只依赖于三个观测量:(1)恒星形成星系的恒星质量函数的红移演化,(2)主序星星系的比恒星形成率(sSFR)的演化,以及(3)固定恒星质量的sSFR分布的双高斯分解(假设红移和质量不变)来自主序星和星暴活动。这个自洽且简单的框架为预测宇宙学观测提供了一个强有力的工具:观测到的IR LF在所有z < 2处都成功匹配,这表明恒星爆发对恒星形成率密度的贡献是恒定的或只有微弱的红移依赖(8-14%)。我们分开的主要序列和星爆活动的全球IR LF在所有的红移的贡献。在0 < z < 2的范围内,星暴分量主导IR LF的光度阈值从log(LIR/Lsun)= 11.4上升到12.8,反映了我们假设的主序星中sSFR的(1+z)^2.8-演化。

英文摘要:

We present a parameter-less approach to predict the shape of the infrared (IR) luminosity function (LF) at redshifts z < 2. It requires no tuning and relies on only three observables: (1) the redshift evolution of the stellar mass function for star-forming galaxies, (2) the evolution of the specific star formation rate (sSFR) of main-sequence galaxies, and (3) the double-Gaussian decomposition of the sSFR-distribution at fixed stellar mass into a contribution (assumed redshift- and mass-invariant) from main-sequence and starburst activity. This self-consistent and simple framework provides a powerful tool for predicting cosmological observables: observed IR LFs are successfully matched at all z < 2, suggesting a constant or only weakly redshift-dependent contribution (8-14%) of starbursts to the star formation rate density. We separate the contributions of main-sequence and starburst activity to the global IR LF at all redshifts. The luminosity threshold above which the starburst component dominates the IR LF rises from log(LIR/Lsun) = 11.4 to 12.8 over 0 < z < 2, reflecting our assumed (1+z)^2.8-evolution of sSFR in main-sequence galaxies.

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