arXiv 1910.032162019-10-08astro-ph.GA

星系的重子质量函数到z=3的演化

The evolution of baryonic mass function of galaxies to z=3

Zhizheng Pan, Yingjie Peng, Xianzhong Zheng, Jing Wang, Xu Kong

备注：: 7 pages, 3 figures, accepted by ApJL
DOI：: 10.3847/2041-8213/ab4bcf

摘要：

结合已发表的恒星质量函数和气体标度关系，探讨了星系的重子（恒星加冷气体）质量函数对$z=3$红移的影响。我们发现的证据表明，在日志$(M_{\rm baryon}/M_{\bigodot})>11.3$，BMF演变很少，因为$z\sim 2.2$。在BMF和SMF演化的基础上，研究了log（$M_{\rm star}/M_{\bigodot}$）>10的星系布居数的重子净吸积率（$\dotρ_{\rm baryon}$）和恒星质量增长率（$\dotρ_{\rm star}$）。这两个量之间的比值$\dotρ_{\rm baryon}$ / $\dotρ_{\rm star}$从$z\sim 2.5$的$\dotρ_{\rm baryon}$ / $\dotρ_{\rm star}\sim$ 2减小到$z\sim 0.5$的$\dotρ_{\rm baryon}$ / $\dotρ_{\rm star}<$ 0.5，表明大质量星系从高$-z$到低$-z$正从“吸积主导”阶段转变为“耗减主导”阶段。这两个相的转变发生在$z\sim1.5$处，这与宇宙星形成率密度下降的起始红移相一致。这为支持$z\sim1.5$以来宇宙恒星形成率密度的下降主要是由于星系中重子净吸积率的下降和恒星形成猝灭的观点提供了证据。

英文摘要：

We combine the published stellar mass function (SMF) and gas scaling relations to explore the baryonic (stellar plus cold gas) mass function (BMF) of galaxies to redshift $z=3$. We find evidence that at log$(M_{\rm baryon}/M_{\bigodot})>11.3$, the BMF evolves little since $z\sim 2.2$. With the evolution of BMF and SMF, we investigate the baryon net accretion rate ($\dotρ_{\rm baryon}$) and stellar mass growth rate ($\dotρ_{\rm star}$) for the galaxy population of log($M_{\rm star}/M_{\bigodot}$)>10. The ratio between these two quanties, $\dotρ_{\rm baryon}$/$\dotρ_{\rm star}$, decreases from $\dotρ_{\rm baryon}$/$\dotρ_{\rm star}\sim$2 at $z\sim 2.5$ to $\dotρ_{\rm baryon}$/$\dotρ_{\rm star}<$0.5 at $z\sim 0.5$, suggesting that massive galaxies are transforming from the "accretion dominated" phase to the "depletion dominated" phase from high$-z$ to low$-z$. The transition of these two phases occurs at $z\sim1.5$, which is consistent with the onset redshift of the decline of cosmic star formation rate density. This provides evidence to support the idea that the decline of cosmic star formation rate density since $z\sim1.5$ is mainly resulted from the decline of baryon net accretion rate and star formation quenching in galaxies.

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