COLDz: A High Space Density of Massive Dusty Starburst Galaxies ∼1 Billion Years after the Big Bang
COLDz: A High Space Density of Massive Dusty Starburst Galaxies ∼1 Billion Years after the Big Bang
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DOI：
10.3847/1538-4357/ab8c48
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发表时间：
2020-04
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通讯作者：
D. Riechers;J. Hodge;R. Pavesi;E. Daddi;R. Decarli;R. Ivison;C. Sharon;I. Smail;F. Walter;M. Aravena;P. Capak;C. Carilli;P. Cox;E. D. Cunha;H. Dannerbauer;M. Dickinson;R. Neri;J. Wagg
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作者：
D. Riechers;J. Hodge;R. Pavesi;E. Daddi;R. Decarli;R. Ivison;C. Sharon;I. Smail;F. Walter;M. Aravena;P. Capak;C. Carilli;P. Cox;E. D. Cunha;H. Dannerbauer;M. Dickinson;R. Neri;J. Wagg
我们报告了通过NSF的Karl G.分子线扫描检测到z > 5的三个大质量尘埃星暴星系的CO（J = 2 → 1）发射。Jansky甚大阵列（VLA）CO高红移光度密度（COLDz）巡天。其中两个源HDF 850.1（z = 5.183）和阿兹特克-3（z = 5.298）的红移是以前已知的。我们修正了先前对第三个源GN 10（z = 5.303）的红移估计，我们已经通过使用VLA和北方扩展毫米波阵列对CO J = 1 → 0，5 → 4，6 → 5和[C ii] 158 μm发射的独立探测证实了这一估计。我们发现，目前独立确认的COLDz中的CO源是“光学暗”的，其中三个是z > 5的尘埃遮蔽星系。考虑到我们的调查区域为1060弧分2，我们的结果似乎意味着在大爆炸后的第一个十亿年内，这种遥远的尘埃系统的空间密度比以前认为的要高106 -55倍。这些z > 5的星系中至少有两个显示出与所谓的“最大”星爆一致的星星形成率表面密度，但我们发现它们之间的CO激发有显着差异。这一结果可能表明，不同部分的大规模的气体水库位于密集的，恒星形成的核区域一致的更广泛的尺寸的[C二]发射相比，尘埃连续和更高的[C二]-远红外光度比在那些星系与较低的气体激发。因此，我们发现z > 5的尘埃星爆之间星星形成的条件有很大的变化，由于它们增强的星星形成活动，这些星爆的尘埃温度通常比z = 2-3的星爆高出57% ± 25%。
We report the detection of CO(J = 2 → 1) emission from three massive dusty starburst galaxies at z > 5 through molecular line scans in the NSF’s Karl G. Jansky Very Large Array (VLA) CO Luminosity Density at High Redshift (COLDz) survey. Redshifts for two of the sources, HDF 850.1 (z = 5.183) and AzTEC-3 (z = 5.298), were previously known. We revise a previous redshift estimate for the third source GN10 (z = 5.303), which we have independently confirmed through detections of CO J = 1 → 0, 5 → 4, 6 → 5, and [C ii] 158 μm emission with the VLA and the NOrthern Extended Milllimeter Array. We find that two currently independently confirmed CO sources in COLDz are “optically dark”, and that three of them are dust-obscured galaxies at z > 5. Given our survey area of ∼60 arcmin2, our results appear to imply a ∼6–55 times higher space density of such distant dusty systems within the first billion years after the Big Bang than previously thought. At least two of these z > 5 galaxies show star formation rate surface densities consistent with so-called “maximum” starbursts, but we find significant differences in CO excitation between them. This result may suggest that different fractions of the massive gas reservoirs are located in the dense, star-forming nuclear regions—consistent with the more extended sizes of the [C ii] emission compared to the dust continuum and higher [C ii]-to-far-infrared luminosity ratios in those galaxies with lower gas excitation. We thus find substantial variations in the conditions for star formation between z > 5 dusty starbursts, which typically have dust temperatures that are ∼57% ± 25% warmer than starbursts at z = 2–3 due to their enhanced star formation activity.