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arXiv 2101.04700astro-ph.GA
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静止星系的星际介质及其随时间的演化

The Interstellar Medium of Quiescent Galaxies and its Evolution With Time

Georgios E. Magdis, R. Gobat, F. Valentino, E. Daddi, A. Zanella, V. Kokorev, S. Toft, S. Jin, K. Whitaker

摘要:

我们研究了大质量静止星系(<log(M*/Msun)> ~ 11.0)的远红外(FIR)基本性质和气体质量分数,并探讨了它们从z = 2.0到现在的演化过程。我们使用稳健的多波长(中到远红外和亚毫米到无线电)堆叠集合,这些堆叠集合是均匀选择的,并且是log(M*/Msun)> 10.8 QG的质量完整样本。我们发现,尘埃与恒星的质量比(Md/M*)作为红移的函数急剧上升到z~1.0,然后保持平坦,至少到z = 2.0。使用Md作为气体质量(Mgas)的代理,我们发现气体质量分数(fgas)的演化具有类似的趋势,其中z > 1.0 QG具有fgas ~ 7.0%(对于太阳金属丰度)。这个fgas比正常的恒星形成星系(SFG)的相应红移低3 - 10倍,但比z = 0.5和本地QG大3和10倍。此外,推断的气体耗尽的时间尺度是可比的本地SFG和系统长于主序星星系在其相应的红移。我们的分析还表明,大质量QG的平均尘埃温度(Td)< Td >至少在z ~ 2.0时保持大致恒定(= 21.0 \pm 2.0 K),并且与z &gt; 0的SFG相比,温度要低得多(~ 10 K)。这促使我们构建并发布了一个红移不变的模板IR SED,我们用它来预测ALMA观测,并探索大质量高z QG的Mgas估计中的系统效应。最后,我们讨论了一个考虑祖先偏差的简单模型如何有效地再现所观察到的Md/M* 和fgas的演变。我们的研究结果表明,普遍的初始星际介质条件淬火星系和大程度的均匀性,在其内部的过程在整个宇宙时间。

英文摘要:

We characterise the basic far-IR (FIR) properties and the gas mass fraction of massive (<log(M*/Msun)> ~ 11.0) quiescent galaxies (QGs) and explore how these evolve from z = 2.0 to the present day. We use robust, multi-wavelength (mid- to far-IR and sub-millimetre to radio) stacking ensembles of homogeneously selected and mass complete samples of log(M*/Msun) > 10.8 QGs. We find that the dust to stellar mass ratio (Md/M*) rises steeply as a function of redshift up to z~1.0 and then remains flat at least out to z = 2.0. Using Md as a proxy of gas mass (Mgas), we find a similar trend for the evolution of the gas mass fraction (fgas) with z > 1.0 QGs having fgas ~ 7.0% (for solar metallicity). This fgas is 3 - 10 times lower than that of normal star forming galaxies (SFGs) at their corresponding redshift but ~3 and ~10 times larger compared to that of z = 0.5 and local QGs. Furthermore, the inferred gas depletion time scales are comparable to that of local SFGs and systematically longer than that of main sequence galaxies at their corresponding redshifts. Our analysis also reveals that the average dust temperature (Td) of massive QGs remains roughly constant (< Td > = 21.0 \pm 2.0K) at least out to z ~ 2.0 and is substantially colder (~ 10K) compared to that of z > 0 SFGs. This motivated us to construct and release a redshift-invariant template IR SED, that we use to make predictions for ALMA observations and to explore systematic effects in the Mgas estimates of massive, high-z QGs. Finally, we discuss how a simple model that considers progenitor-bias can effectively reproduce the observed evolution of Md/M* and fgas. Our results indicate universal initial interstellar medium conditions for quenched galaxies and a large degree of uniformity in their internal processes across cosmic time.

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