Rejuvenation in z ∼ 0.8 Quiescent Galaxies in LEGA-C
Rejuvenation in z ∼ 0.8 Quiescent Galaxies in LEGA-C
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DOI：
10.3847/1538-4357/ab164d
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发表时间：
2019-05
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通讯作者：
Priscilla Chauké;A. van der Wel;C. Pacifici;R. Bezanson;Po-Feng Wu;A. Gallazzi;C. Straatman;M. Franx;I. Barišić;E. Bell;J. van Houdt;M. Maseda;A. Muzzin;D. Sobral;J. Spilker
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作者：
Priscilla Chauké;A. van der Wel;C. Pacifici;R. Bezanson;Po-Feng Wu;A. Gallazzi;C. Straatman;M. Franx;I. Barišić;E. Bell;J. van Houdt;M. Maseda;A. Muzzin;D. Sobral;J. Spilker
我们使用重建的星星形成（SF）的历史，在z = 0.6-1的大型早期星系天体物理普查，以确定次级SF情节，经过最初的一段时间的静止，移动的星系回到恒星形成的主要序列（蓝色云）。在z <0.8的静止星群中，有16 ± 3%的星群在较早的时间达到静止后，在红移0.7 < z < 1.5的范围内经历了这样的返老还童事件。平均而言，这些星系在z = 1.2时开始静止，而那些恢复活力的星系在它们的第二次SF事件之前保持静止2.1 Gyr，持续了2.07 Gyr。再生的恒星质量平均为星系恒星质量的10%，很少有增加超过2倍的情况。总的来说，在z = 0.8的静止星系中，再生事件只贡献了恒星总质量的1.2%，我们得出结论，当考虑红色序列的增长时，再生不是一个重要的演化通道。然而，我们的研究结果复杂的解释星系人口在颜色空间：星系的复兴事件往往位于所谓的“绿色谷”，但他们的祖先是静止的z 102。
We use reconstructed star formation (SF) histories of quiescent galaxies at z = 0.6–1 in the Large Early Galaxy Astrophysics Census survey to identify secondary SF episodes that, after an initial period of quiescence, moved the galaxies back to the star-forming main sequence (blue cloud). 16 ± 3% of the z ∼ 0.8 quiescent population has experienced such rejuvenation events in the redshift range of 0.7 < z < 1.5 after reaching quiescence at some earlier time. On average, these galaxies first became quiescent at z = 1.2, and those that rejuvenated, remained quiescent for ∼1 Gyr before their secondary SF episode, which lasted ∼0.7 Gyr. The stellar mass attributed to rejuvenation is on average 10% of the galaxy stellar mass, with rare instances of an increase of more than a factor of 2. Overall, rejuvenation events only contribute ∼2% of the total stellar mass in z ∼ 0.8 quiescent galaxies and we conclude that rejuvenation is not an important evolutionary channel when considering the growth of the red sequence. However, our results complicate the interpretation of galaxy demographics in color space: the galaxies with rejuvenation events tend to lie in the so-called “green valley,” yet their progenitors were quiescent at z ∼ 2.