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arXiv · 2010.07302

Constraints on the [CII] luminosity of a proto-globular cluster at z~6 obtained with ALMA

F. Calura·E. Vanzella·S. Carniani·R. Gilli·P. Rosati·M. Meneghetti·R. Paladino·R. Decarli·M. Brusa·A. Lupi·Q. D'Amato·P. Bergamini·. G. B. Caminha·-
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Abstract

We report on ALMA observations of D1, a system at z~6.15 with stellar mass M_* ~ 10^7 M_sun containing globular cluster (GC) precursors, strongly magnified by the galaxy cluster MACS J0416.1-2403. Since the discovery of GC progenitors at high redshift, ours is the first attempt to probe directly the physical properties of their neutral gas through infrared observations. A careful analysis of our dataset, performed with a suitable procedure designed to identify faint narrow lines and which can test various possible values for the unknown linewidth value, allowed us to identify a 4-sigma tentative detection of [CII] emission with intrinsic luminosity L_CII=(2.9 +/- 1.4) 10^6 L_sun, one of the lowest values ever detected at high redshift. This study offers a first insight on previously uncharted regions of the L_CII-SFR relation. Despite large uncertainties affecting our measure of the star formation rate, if taken at face value our estimate lies more than 1 dex below the values observed in local and high redshift systems. Our weak detection indicates a deficiency of [CII] emission, possibly ascribed to various explanations, such as a low-density gas and/or a strong radiation field caused by intense stellar feedback, and a low metal content. From the non-detection in the continuum we derive constraints on the dust mass, with 3-sigma upper limit values as low as a few 10^4 M_sun, consistent with the values measured in local metal-poor galaxies.

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F. Calura, E. Vanzella, S. Carniani, R. Gilli, P. Rosati, M. Meneghetti, R. Paladino, R. Decarli, M. Brusa, A. Lupi, Q. D'Amato, P. Bergamini, . G. B. Caminha, -. 2020-10-14. Constraints on the [CII] luminosity of a proto-globular cluster at z~6 obtained with ALMA. https://doi.org/10.1093/mnras/staa3185

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