论文标题
VLA-COSMOS 3 GHz大型项目：特定恒星形成率的演变至$ z \ sim5 $
The VLA-COSMOS 3 GHz Large Project: Evolution of specific star formation rates out to $z\sim5$
论文作者
论文摘要
我们提供了对数星形形成率（SFR） - 恒星质量（$ M _*$）关系的连贯，均匀的测量，称为星形星系（MS）的主要序列，用于星系为$ z \ sim5 $。我们使用3 GHz无线电连续图的平均堆栈测量MS，以$ \ sim $ \ sim $ \ sim的平均SFRS在Cosmos Field中以$ z> 0.3 $的形式得出平均sfrs。我们描述了采用新模型的MS关系，该模型结合了低恒星质量（log（$ m _*$/m $ $ _ \ odot $）$ <$ 10）的线性关系，并且在高恒星质量上的变平上变得更加突出，在低红移（$ z <1.5 $）上变得更加突出。我们发现SFR密度在$ 1.5 <z <2 $上达到峰值，并且在每个时期都有一个特征性的恒星质量（$ m_* = 1-4 \ times 10^{10} \ Mathrm {M} _ \ odot $），对整个SFR密度贡献最大。这种特征质量随红移而增加，至少为$ z \ sim2.5 $。我们没有发现在$ 0.3 <z <3 $ $ 0.3 <z <3 $的不同环境中，在不同环境中的MS关系变化的显着证据，也没有针对X射线组的星系$ z \ sim0.75 $。我们确认，以固定的恒星质量为$ z <1.2 $，大型凸出隆起的星系的SFR比磁盘为主导的星系低。结果，局部恒星形成人群中凸出主导的星系的增加导致高恒星质量下MS的变平。这表明“质量衡量”与固定恒星质量处星系的形态组成的变化有关。
We provide a coherent, uniform measurement of the evolution of the logarithmic star formation rate (SFR) - stellar mass ($M_*$) relation, called the main sequence of star-forming galaxies (MS), for galaxies out to $z\sim5$. We measure the MS using mean stacks of 3 GHz radio continuum images to derive average SFRs for $\sim$200,000 mass-selected galaxies at $z>0.3$ in the COSMOS field. We describe the MS relation adopting a new model that incorporates a linear relation at low stellar mass (log($M_*$/M$_\odot$)$<$10) and a flattening at high stellar mass that becomes more prominent at low redshift ($z<1.5$). We find that the SFR density peaks at $1.5<z<2$ and at each epoch there is a characteristic stellar mass ($M_* = 1 - 4 \times 10^{10}\mathrm{M}_\odot$) that contributes the most to the overall SFR density. This characteristic mass increases with redshift, at least to $z\sim2.5$. We find no significant evidence for variations in the MS relation for galaxies in different environments traced by the galaxy number density at $0.3<z<3$, nor for galaxies in X-ray groups at $z\sim0.75$. We confirm that massive bulge-dominated galaxies have lower SFRs than disk-dominated galaxies at a fixed stellar mass at $z<1.2$. As a consequence, the increase in bulge-dominated galaxies in the local star-forming population leads to a flattening of the MS at high stellar masses. This indicates that "mass-quenching" is linked with changes in the morphological composition of galaxies at a fixed stellar mass.
