Dust, gas, and metal content in star-forming galaxies at $z\sim3.3$ revealed with ALMA and Near-IR spectroscopy

Suzuki, Tomoko L. and Onodera, Masato and Kodama, Tadayuki and Daddi, Emanuele and Hayashi, Masao and Koyama, Yusei and Shimakawa, Rhythm and Smail, Ian and Sobral, David and Tacchella, Sandro and Tanaka, Ichi (2021) Dust, gas, and metal content in star-forming galaxies at $z\sim3.3$ revealed with ALMA and Near-IR spectroscopy. The Astrophysical Journal, 908 (1): 15. ISSN 0004-637X

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Abstract

We conducted sub-millimeter observations with the Atacama Large Millimeter/sub-millimeter Array (ALMA) of star-forming galaxies at $z\sim3.3$, whose gas-phase metallicities have been previously measured. We investigate the dust and gas contents of the galaxies at $z\sim3.3$ and study how galaxies are interacting with their circumgalactic/intergalactic medium at this epoch by probing their gas mass fractions and gas-phase metallicities. Single-band dust continuum emission tracing dust mass and the relation between the gas-phase metallicity and gas-to-dust mass ratio are used to estimate the gas masses. The estimated gas mass fractions and depletion timescales are $f_{\rm gas}=$ 0.20-0.75 and $t_{\rm dep}=$ 0.09-1.55 Gyr, respectively. Although the galaxies appear to tightly distribute around the star-forming main sequence at $z\sim3.3$, both quantities show a wider spread at a fixed stellar mass than expected from the scaling relation, suggesting a large diversity of fundamental gas properties among star-forming galaxies apparently on the main sequence. Comparing gas mass fraction and gas-phase metallicity between the star-forming galaxies at $z\sim3.3$ and at lower redshifts, star-forming galaxies at $z\sim3.3$ appear to be more metal-poor than local galaxies with similar gas mass fractions. Using the gas regulator model to interpret this offset, we find that it can be explained by a higher mass-loading factor, suggesting that the mass-loading factor in outflows increases at earlier cosmic times.