A Glimpse of the Stellar Populations and Elemental Abundances of Gravitationally Lensed, Quiescent Galaxies at z ≳ 1 with Keck Deep Spectroscopy
A Glimpse of the Stellar Populations and Elemental Abundances of Gravitationally Lensed, Quiescent Galaxies at z ≳ 1 with Keck Deep Spectroscopy
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DOI：
10.3847/1538-4357/acc79b
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发表时间：
2022-12
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通讯作者：
Z. Zhuang;N. Leethochawalit;E. Kirby;J. Nightingale;C. Steidel;K. Glazebrook;T. Barone;Hannah Skobe;S. Sweet;T. Nanayakkara;R. Allen;Keerthi Vasan G. C.;T. Jones;G. Kacprzak;K. Tran;C. Jacobs
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作者：
Z. Zhuang;N. Leethochawalit;E. Kirby;J. Nightingale;C. Steidel;K. Glazebrook;T. Barone;Hannah Skobe;S. Sweet;T. Nanayakkara;R. Allen;Keerthi Vasan G. C.;T. Jones;G. Kacprzak;K. Tran;C. Jacobs
引力透镜可以放大遥远的星系，使我们能够发现和描述本质上微弱的恒星群，静止的星系，否则很难从地面望远镜直接观察到高红移。在这里，我们提出了光谱分析的两个透镜，静止星系在z 1发现的ASTRO三维星系演化与透镜调查：AGEL 1323（M *<$1011.1 M <$，z = 1.016，μ <$14.6）和AGEL 0014（M *<$1011.5 M <$，z = 1.374，μ <$4.3）。我们用凯克一号望远镜获得的深静止坐标系光谱（S/N = 40 <$−1）测量了这两个透镜星系的年龄、[Fe/H]和[Mg/Fe]。AGEL 1323和AGEL 0014的年龄分别为5.6−0.8+0.8 Gyr和3.1−0.3+0.8 Gyr，表明星系中的大多数恒星在大爆炸后不到2 Gyr形成。与附近质量相似的静止星系相比，透镜星系具有较低的[Fe/H]和[Mg/H]。令人惊讶的是，这两个星系的[Mg/Fe]与红移较低的类似质量星系相当，尽管它们的年龄很大。使用一个简单的分析化学演化模型连接瞬间回收的元素镁的质量负载因子的流出平均在整个星星形成的历史，我们发现，透镜星系可能经历了增强的流出在其星星形成相比，较低的红移星系，这可能解释了为什么他们淬火早。
Gravitational lenses can magnify distant galaxies, allowing us to discover and characterize the stellar populations of intrinsically faint, quiescent galaxies that are otherwise extremely difficult to directly observe at high redshift from ground-based telescopes. Here, we present the spectral analysis of two lensed, quiescent galaxies at z ≳ 1 discovered by the ASTRO 3D Galaxy Evolution with Lenses survey: AGEL1323 (M * ∼ 1011.1 M ⊙, z = 1.016, μ ∼ 14.6) and AGEL0014 (M * ∼ 1011.5 M ⊙, z = 1.374, μ ∼ 4.3). We measured the age, [Fe/H], and [Mg/Fe] of the two lensed galaxies using deep, rest-frame-optical spectra (S/N ≳40 Å−1) obtained on the Keck I telescope. The ages of AGEL1323 and AGEL0014 are 5.6−0.8+0.8 Gyr and 3.1−0.3+0.8 Gyr, respectively, indicating that most of the stars in the galaxies were formed less than 2 Gyr after the Big Bang. Compared to nearby quiescent galaxies of similar masses, the lensed galaxies have lower [Fe/H] and [Mg/H]. Surprisingly, the two galaxies have comparable [Mg/Fe] to similar-mass galaxies at lower redshifts, despite their old ages. Using a simple analytic chemical evolution model connecting the instantaneously recycled element Mg with the mass-loading factors of outflows averaged over the entire star formation history, we found that the lensed galaxies may have experienced enhanced outflows during their star formation compared to lower-redshift galaxies, which may explain why they quenched early.