We report on ALMA observations of D1, a system at z ∼ 6.15 with stellar mass M∗ ∼ 107M 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 4σ tentative detection of [CII] emission with intrinsic luminosity L[CII] = (2.9 ± 1.4) 106L, one of the lowest values ever detected at high redshift. This study offers a first insight on previously uncharted regions of the L[CII] − SF R 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 − σ upper limit values as low as ∼ a few 104 M, consistent with the values measured in local metal-poor galaxies.
|Titolo:||Constraints on the [CII] luminosity of a proto-globular cluster at z ∼ 6 obtained with ALMA|
|Data di pubblicazione:||2021|
|Settore Scientifico Disciplinare:||Settore FIS/05 - Astronomia e Astrofisica|
|Parole Chiave:||galaxies: high-redshift - galaxies: ISM - submillimetre: ISM - gravitational lensing: strong|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1093/mnras/staa3185|
|Appare nelle tipologie:||1.1 Articolo in rivista|