Elemental Abundances and Ages of z ∼ 0.7 Quiescent Galaxies on the Mass–Size Plane: Implication for Chemical Enrichment and Star Formation Quenching
Elemental Abundances and Ages of z ∼ 0.7 Quiescent Galaxies on the Mass–Size Plane: Implication for Chemical Enrichment and Star Formation Quenching
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DOI：
10.3847/2041-8213/ac12cd
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发表时间：
2021-05
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通讯作者：
Aliza G. Beverage;M. Kriek;C. Conroy;R. Bezanson;M. Franx;A. van der Wel
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作者：
Aliza G. Beverage;M. Kriek;C. Conroy;R. Bezanson;M. Franx;A. van der Wel
本文给出了LEGA-C巡天中65个0.59 ≤ z ≤ 0.75的大质量静止星系的元素丰度和恒星年龄。从全光谱模型中得出的丰度模式和年龄，作为恒星质量（M *）和大小（即，半光半径，Re）。我们发现[Mg/H]和[Fe/H]都不随恒星质量而变化，但对于M * > 1010.5 M <$的静止星系，它们与M */Re相关。因此，在固定质量下，致密的静止星系平均来说更富含金属。这一结果强化了超新星反馈和引力势调节化学富集的观点。[Mg/Fe]不随M * 或M */Re而变化，但年龄与质量之间存在边际正相关。我们的研究结果支持了低红移的发现，即更大质量的星系在更早的时间形成它们的恒星。然而，与低红移的研究相反，星星形成的时间尺度似乎并不依赖于质量或大小。我们还比较了z = 0时静止星系堆的质量-[Fe/H]和质量-[Mg/H]关系，发现这两种关系在过去的7 Gyr中都增加了10.2 dex。此外，在z = 0.7，我们发现一个明显的趋势，随着年龄的增长，这样的老静止星系有较低的金属丰度。这两个结果都可以用化学演化模型来解释，在这个模型中，星系通过气体的去除而淬灭。未来的工作，特别是与詹姆斯韦伯太空望远镜/NIRSpec，将这种分析扩展到更高的红移，使我们能够充分利用丰度模式来研究静止星系的形成历史。
We present elemental abundances and stellar population ages for 65 massive quiescent galaxies at 0.59 ≤ z ≤ 0.75 from the LEGA-C survey. The abundance patterns and ages, derived from full-spectrum modeling, are examined as a function of stellar mass (M *) and size (i.e., half-light radius, R e ). We find that both [Mg/H] and [Fe/H] do not vary with stellar mass but are correlated with M */R e for quiescent galaxies with M * > 1010.5 M ⊙. Thus, at fixed mass, compact quiescent galaxies are on average more metal-rich. This result reinforces the picture that supernova feedback and gravitational potential regulate chemical enrichment. [Mg/Fe] does not vary with M * or M */R e , but there is a marginal positive relation between age and mass. Our results support low-redshift findings that more massive galaxies form their stars at earlier times. However, in contrast to low-redshift studies, star formation timescale does not appear to depend on mass or size. We also compare the mass–[Fe/H] and mass–[Mg/H] relations to stacks of quiescent galaxies at z ∼ 0 and find that both relations increase by ∼0.2 dex over the past 7 Gyr. Furthermore, at z ∼ 0.7 we find a clear trend with age, such that older quiescent galaxies have lower metallicities. Both results can be explained by a chemical evolution model in which galaxies quench via gas removal. Future work, in particular with James Webb Space Telescope/NIRSpec, will extend this analysis to higher redshifts, allowing us to fully exploit abundance patterns to study the formation histories of quiescent galaxies.