Recent Star Formation in a Massive Slowly Quenched Lensed Quiescent Galaxy at z = 1.88
Recent Star Formation in a Massive Slowly Quenched Lensed Quiescent Galaxy at z = 1.88
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DOI：
10.3847/2041-8213/abd416
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发表时间：
2020-12
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通讯作者：
Mohammad Akhshik;K. Whitaker;J. Leja;G. Mahler;K. Sharon;G. Brammer;S. Toft;R. Bezanson;A. Man;E. Nelson;C. Pacifici;S. Wellons;C. Williams
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作者：
Mohammad Akhshik;K. Whitaker;J. Leja;G. Mahler;K. Sharon;G. Brammer;S. Toft;R. Bezanson;A. Man;E. Nelson;C. Pacifici;S. Wellons;C. Williams
在这封信中，我们重建了 MRG-S0851 的形成路径，这是一个巨大的 logM*/M⊙=11.02±0.04 强透镜状红色星系，z = 1.883 ± 0.001。虽然 MRG-S0851 的全局光度测量和空间分辨的外围意味着早期形成场景，恒星形成历史缓慢减少或恒定，但二维棱镜光谱和光度测量的联合拟合揭示了一个更复杂的场景：MRG-S0851 很可能在最后 ∼100 Myr 的演化中在内部 ∼1 kpc 中经历集中的再生。我们估计总恒星质量的 0.5 ± 0.1% 是在这个阶段形成的。对于 z ∼ 2 的大质量星系来说，再生事件被认为是罕见的，但正如我们的分析表明的那样，更多复杂恒星形成历史的例子可能隐藏在现有数据中。通过在标准 U-V/V-J 诊断中添加 FUV 颜色标准，从而提高我们对近期恒星形成的敏感性，我们表明我们可以选择与 MRG-S0851 具有相似光谱能量分布的星系群，但请注意，深入的后续光谱观测和/或空间分辨分析对于稳健地确认这些候选星系的复兴是必要的。使用我们的标准，以 MRG-S0851 作为原型，我们估计大约 1% 1 < z < 2 的大质量静止星系有可能恢复活力。
In this Letter, we reconstruct the formation pathway of MRG-S0851, a massive, logM*/M⊙=11.02±0.04 , strongly lensed, red galaxy at z = 1.883 ± 0.001. While the global photometry and spatially resolved outskirts of MRG-S0851 imply an early formation scenario with a slowly decreasing or constant star formation history, a joint fit of 2D grism spectroscopy and photometry reveals a more complex scenario: MRG-S0851 is likely to be experiencing a centrally concentrated rejuvenation in the inner ∼1 kpc in the last ∼100 Myr of evolution. We estimate 0.5 ± 0.1% of the total stellar mass is formed in this phase. Rejuvenation episodes are suggested to be infrequent for massive galaxies at z ∼ 2, but as our analyses indicate, more examples of complex star formation histories may yet be hidden within existing data. By adding an FUV color criterion to the standard U–V/V–J diagnostic—thereby heightening our sensitivity to recent star formation—we show that we can select populations of galaxies with similar spectral energy distributions to that of MRG-S0851, but note that deep follow-up spectroscopic observations and/or spatially resolved analyses are necessary to robustly confirm the rejuvenation of these candidates. Using our criteria with MRG-S0851 as a prototype, we estimate that ∼1% of massive quiescent galaxies at 1 < z < 2 are potentially rejuvenating.