Mapping Obscuration to Reionization with ALMA (MORA): 2 mm Efficiently Selects the Highest-redshift Obscured Galaxies
Mapping Obscuration to Reionization with ALMA (MORA): 2 mm Efficiently Selects the Highest-redshift Obscured Galaxies
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DOI：
10.3847/1538-4357/ac2eb4
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发表时间：
2021-10
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通讯作者：
C. Casey;J. Zavala;S. Manning;M. Aravena;M. Béthermin;K. Caputi;J. Champagne;D. Clements;P. Drew;S. Finkelstein;S. Fujimoto;C. Hayward;A. Koekemoer;V. Kokorev;Claudia del P. Lagos;A. Long;G. Magdis;A. Man;I. Mitsuhashi;G. Popping;J. Spilker;J. Staguhn;M. Talia;S. Toft;E. Treister;J. Weaver;M. Yun
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作者：
C. Casey;J. Zavala;S. Manning;M. Aravena;M. Béthermin;K. Caputi;J. Champagne;D. Clements;P. Drew;S. Finkelstein;S. Fujimoto;C. Hayward;A. Koekemoer;V. Kokorev;Claudia del P. Lagos;A. Long;G. Magdis;A. Man;I. Mitsuhashi;G. Popping;J. Spilker;J. Staguhn;M. Talia;S. Toft;E. Treister;J. Weaver;M. Yun
我们介绍了迄今为止进行的最大的阿塔卡马大型毫米/亚毫米阵列 (ALMA) 空白场连续勘测中选定的 2 毫米源的特征，即 ALMA 测绘遮蔽到再电离 (MORA) 勘测，覆盖 2 毫米处的 184 arcmin2。 13 个高于 5σ 的探测中有 12 个归因于星系的发射，其中 11 个主要是冷尘埃发射。这些源的中值红移为 <z2mm>=3.6−0.3+0.4，主要基于光学/近红外光度红移和一些光谱红移，其中 77% ± 11% 的源位于 z > 3，38% ± 12% 的源位于 z > 4。这意味着 2 mm 选择是识别红移最高的尘埃恒星形成星系的有效方法（DSFG）。较低红移的 DSFG (z 3 但很可能在 2 mm 处消失。MORA 表明，恒星形成率超过 300 M ⊙ yr−1 且相对稀有度为 ∼10−5 Mpc−3 的 DSFG 对 3 2 处的综合恒星形成率密度贡献了 ∼30%。MORA 源光谱能量分布的分析表明，经验测量的尘埃发射率指数比典型文献研究中报道的更陡峭， 〈β〉=2.2−0.4+0.5 MORA 巡天代表了对宇宙最初几十亿年的模糊恒星形成进行普查的重要一步，但需要更大面积的 2 毫米巡天来更全面地描述这一稀有星系的特征，并推动宇宙中第一批尘埃星系的探测。
We present the characteristics of 2 mm selected sources from the largest Atacama Large Millimeter/submillimeter Array (ALMA) blank-field contiguous survey conducted to date, the Mapping Obscuration to Reionization with ALMA (MORA) survey covering 184 arcmin2 at 2 mm. Twelve of 13 detections above 5σ are attributed to emission from galaxies, 11 of which are dominated by cold dust emission. These sources have a median redshift of 〈z2mm〉=3.6−0.3+0.4 primarily based on optical/near-infrared photometric redshifts with some spectroscopic redshifts, with 77% ± 11% of sources at z > 3 and 38% ± 12% of sources at z > 4. This implies that 2 mm selection is an efficient method for identifying the highest-redshift dusty star-forming galaxies (DSFGs). Lower-redshift DSFGs (z 3 yet are likely to drop out at 2 mm. MORA shows that DSFGs with star formation rates in excess of 300 M ⊙ yr−1 and a relative rarity of ∼10−5 Mpc−3 contribute ∼30% to the integrated star formation rate density at 3 2. Analysis of MORA sources’ spectral energy distributions hint at steeper empirically measured dust emissivity indices than reported in typical literature studies, with 〈β〉=2.2−0.4+0.5 . The MORA survey represents an important step in taking census of obscured star formation in the universe’s first few billion years, but larger area 2 mm surveys are needed to more fully characterize this rare population and push to the detection of the universe’s first dusty galaxies.