论文标题
星系星形成历史的柔性模型既偏移又有光学颜色-M/L关系
Flexible Models for Galaxy Star Formation Histories Both Shift and Scramble the Optical Color-M/L Relationship
论文作者
论文摘要
星系光学色与恒星质量与光比（$ M _*/l $）之间的密切紧密关系被广泛用于有效的出色质量估计。但是，尚不清楚这种低散射是否来自银河系中的自然顺序，还是它是由用于描述它们的模型中的简单关系所驱动的。在这项工作中，我们通过将来自简单的4参数SED模型的派生关系与更复杂的14维探矿者$ $α$模型（包括非参数星形形成历史（SFHS））进行了对比，研究了关系的起源。我们以$ 0.5 <z <3 $的价格将这些型号应用于63,430个星系，并适合层级贝叶斯型号（HBM），以$（g-r）$ - $ \ log（m/l_g）$ plane的人口分布。我们发现，探矿者$α$在系统上更高的$ m _*/l $ by 0.12 dex，这是非参数sfhs产生较老的年龄的结果，并且由于源自源发射的贡献，因此系统地生产了较老的年龄较大的sfhs dex。令人惊讶的是，与0.12 DEX的简单模型相比，$ m _*/l $和$（G-R）$ offset的综合效果对这两种模型产生了相似的平均关系，尽管勘探者$α$的散布较高0.28 dex。同样，与简单的模型不同，由于出色的衰老，探矿者$α$关系显示出很大的红移进化。这些预期和可测试的效果会产生整体较旧的和红色的星系，尽管颜色-M _*/L $关系仅计量为$ 0.5 <z <3 $。最后，我们证明了HBM在微弱星系的个体后代中产生大量的收缩，这是迈向使用观察到的星系种群直接告知SED拟合先验的重要第一步。
The remarkably tight relationship between galaxy optical color and stellar mass-to-light ratio ($M_*/L$) is widely used for efficient stellar mass estimates. However, it remains unclear whether this low scatter comes from a natural order in the galaxy population, or whether it is driven by simple relationships in the models used to describe them. In this work we investigate the origins of the relationship by contrasting the derived relationship from a simple 4-parameter SED model with a more sophisticated 14-dimensional Prospector-$α$ model including nonparametric star formation histories (SFHs). We apply these models to 63,430 galaxies at $0.5<z<3$ and fit a hierarchical Bayesian model (HBM) to the population distribution in the $(g-r)$--$\log(M/L_g)$ plane. We find that Prospector-$α$ infers systematically higher $M_*/L$ by 0.12 dex, a result of nonparametric SFHs producing older ages, and also systematically redder rest-frame $(g-r)$ by 0.06 mag owing to the contribution from nebular emission. Surprisingly, the combined effects of the $M_*/L$ and $(g-r)$ offsets produce a similar average relationship for the two models, though Prospector-$α$ produces a higher scatter of 0.28 dex compared to the simple model of 0.12 dex. Also, unlike the simple model, the Prospector-$α$ relationship shows substantial redshift evolution due to stellar aging. These expected and testable effects produce overall older and redder galaxies, though the color--$M_*/L$ relationship is measured only at $0.5<z<3$. Finally, we demonstrate that the HBM produces substantial shrinkage in the individual posteriors of faint galaxies, an important first step toward using the observed galaxy population directly to inform the SED fitting priors.
