Physical Characterization of an Unlensed, Dusty Star-forming Galaxy at z = 5.85-猫眼课题宝

DOI：

10.3847/1538-4357/ab52ff

发表时间：

2019-10

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：

C. Casey;J. Zavala;M. Aravena;M. Béthermin;K. Caputi;J. Champagne;D. Clements;E. D. Cunha;P. Drew;S. Finkelstein;C. Hayward;J. Kartaltepe;K. Knudsen;A. Koekemoer;G. Magdis;A. Man;S. Manning;N. Scoville;K. Sheth;J. Spilker;J. Staguhn;M. Talia;Y. Taniguchi;S. Toft;E. Treister;M. Yun

我们提供了MM J100026.36+021527.9（又名：曼波9（Mambo-9），一个尘埃恒星形成星系（DSFG），z = 5.850 ± 0.001。这是迄今为止发现的最高红移的无透镜DSFG（和第四个最遥远的整体），也是COSMOS领域新的2 mm空白场地图中确定的第一个来源。虽然在850 μm到1.2 mm的DSFG的先前样本中识别出了未知的红移，但在2 mm处的检测促使进一步的随访，因为它表明源可能位于z > 4的概率要高得多。本文介绍的阿塔卡马大型毫米波和亚毫米波阵列（阿尔马）的深层观测通过对12 CO（J = 6→5）和p-H_2 O（21，1 → 20，2）的安全探测证实了红移。曼波9由一对相距6千秒差距的星系组成，对应的星星形成速率分别为590 M yr−1和220 M yr−1，氢气分子总质量为（1.7 ± 0.4）× 1011 M，尘埃质量为（1.3 ± 0.3）× 109 M，恒星质量为（）× 109 M。晕的总质量为（3.3 ± 0.8）× 1012 M，预计在z = 0时超过1015 M。该系统正在经历一个合并驱动的星暴，在τdepl = 40−80 Myr时，该系统的恒星质量将增加10倍，将其巨大的分子气体库（气体部分）转化为恒星。Mambo-9在过去的十年里一直没有得到可靠的光谱鉴定，这是因为它遵循了一些最高红移的DSFG的模式。然而，系统地鉴定像Mambo-9这样的无透镜DSFG是测量模糊星星形成对z = 4处星星形成率密度的全球贡献的关键，z = 4是第一个大质量星系的形成，以及早期星际尘埃的形成（1991年）。

We present a physical characterization of MM J100026.36+021527.9 (a.k.a. “Mambo-9”), a dusty star-forming galaxy (DSFG) at z = 5.850 ± 0.001. This is the highest-redshift unlensed DSFG (and fourth most distant overall) found to date and is the first source identified in a new 2 mm blank-field map in the COSMOS field. Though identified in prior samples of DSFGs at 850 μm to 1.2 mm with unknown redshift, the detection at 2 mm prompted further follow-up as it indicated a much higher probability that the source was likely to sit at z > 4. Deep observations from the Atacama Large Millimeter and submillimeter Array (ALMA) presented here confirm the redshift through the secure detection of 12CO(J = 6→5) and p-H2O (21,1 → 20,2). Mambo-9 is composed of a pair of galaxies separated by 6 kpc with corresponding star formation rates of 590 M⊙ yr−1 and 220 M⊙ yr−1, total molecular hydrogen gas mass of (1.7 ± 0.4) × 1011M⊙, dust mass of (1.3 ± 0.3) × 109M⊙, and stellar mass of ( ) × 109M⊙. The total halo mass, (3.3 ± 0.8) × 1012M⊙, is predicted to exceed 1015M⊙ by z = 0. The system is undergoing a merger-driven starburst that will increase the stellar mass of the system tenfold in τdepl = 40−80 Myr, converting its large molecular gas reservoir (gas fraction of ) into stars. Mambo-9 evaded firm spectroscopic identification for a decade, following a pattern that has emerged for some of the highest-redshift DSFGs found. And yet, the systematic identification of unlensed DSFGs like Mambo-9 is key to measuring the global contribution of obscured star formation to the star formation rate density at z ≳ 4, the formation of the first massive galaxies, and the formation of interstellar dust at early times (≲1 Gyr).

Physical Characterization of an Unlensed, Dusty Star-forming Galaxy at z = 5.85

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