Quiescent Galaxies 1.5 Billion Years after the Big Bang and Their Progenitors-猫眼课题宝

DOI：

10.3847/1538-4357/ab64dc

发表时间：

2019-09

期刊：

The Astrophysical Journal

影响因子：

通讯作者：

中科院分区：

其他

文献类型：

作者：

F. Valentino;Masayuki Tanaka;I. Davidzon;S. Toft;C. Gómez-Guijarro;M. Stockmann;M. Onodera;G. Brammer;D. Ceverino;A. Faisst;A. Gallazzi;C. Hayward;O. Ilbert;M. Kubo;G. Magdis;J. Selsing;R. Shimakawa;M. Sparre;C. Steinhardt;K. Yabe;J. Zabl

我们报告了通过Keck/MOSFIRE和超大望远镜/X-Shooter的K波段观测对大质量静止星系的两个安全（）和一个初步（z ≈ 3.767）光谱确认。恒星的连续辐射，没有强的星云发射线，也没有显著的远红外探测，证实了这些天体的被动性质，不利于低红移尘埃恒星形成的闯入者的替代解决方案。我们推导出log（M/M）<$11的恒星质量和正在进行的星星形成率，将这些星系放置在它们的红移低于主序星的<$1 -2 dex。所采用的星星形成历史的参数化表明，这些源经历了一个强烈的（M yr−1）和短暂的（1.5亿年）的星星形成爆发，在观测时间之前达到1.5亿~ 5亿年的峰值，所有的特性都让人想起z > 4的亚毫米星系（SMG）的特征。我们通过比较这两个种群的同动数密度和性质来研究这种联系。我们发现一个公平的协议，只有最深的亚毫米级调查不仅检测到最极端的星爆，但也更正常的星系。我们通过进一步探索Illustris TNG宇宙学模拟来支持这些发现，检索了z = 3-4的完全猝灭大质量星系和z = 4 - 5的SMG的种群，其数量密度和性质与z = 3的观测结果一致，但在更高的红移处增加了张力。然而，正如观测结果所表明的那样，并非所有处于这些红移的静止星系的祖先在它们的过去都像明亮的SMG一样发光，同样地，并非所有明亮的SMG都在z = 3时熄灭，这两个分数取决于假设定义SMG本身的阈值。

We report two secure ( ) and one tentative (z ≈ 3.767) spectroscopic confirmations of massive and quiescent galaxies through K-band observations with Keck/MOSFIRE and Very Large Telescope/X-Shooter. The stellar continuum emission, absence of strong nebular emission lines, and lack of significant far-infrared detections confirm the passive nature of these objects, disfavoring the alternative solution of low-redshift dusty star-forming interlopers. We derive stellar masses of log(M⋆/M⊙) ∼ 11 and ongoing star formation rates placing these galaxies ≳1–2 dex below the main sequence at their redshifts. The adopted parameterization of the star formation history suggests that these sources experienced a strong ( M⊙ yr−1) and short (∼50 Myr) burst of star formation, peaking ∼150–500 Myr before the time of observation, all properties reminiscent of the characteristics of submillimeter galaxies (SMGs) at z > 4. We investigate this connection by comparing the comoving number densities and the properties of these two populations. We find a fair agreement only with the deepest submillimeter surveys detecting not only the most extreme starbursts but also more normal galaxies. We support these findings by further exploring the Illustris TNG cosmological simulation, retrieving populations of both fully quenched massive galaxies at z ∼ 3–4 and SMGs at z ∼ 4−5, with number densities and properties in agreement with the observations at z ∼ 3 but in increasing tension at higher redshift. Nevertheless, as suggested by the observations, not all of the progenitors of quiescent galaxies at these redshifts shine as bright SMGs in their past, and, similarly, not all bright SMGs quench by z ∼ 3, both fractions depending on the threshold assumed to define the SMGs themselves.

Quiescent Galaxies 1.5 Billion Years after the Big Bang and Their Progenitors

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