Molecular gas budget of strongly magnified low-mass star-forming galaxies at cosmic noon

Abstract

This study aims to investigate the molecular gas content of strongly magnified low-mass star-forming galaxies around the cosmic noon period ($z\sim 2$) through observations of CO emission lines and dust continuum emission, both of which serve as tracers for molecular gas. We observed twelve strongly lensed galaxies with the Atacama Compact Array to detect CO mid-j rotational transitions and dust continuum. Thanks to the strong lensing, we were able to probe the low-mass regime, previously understudied. With a compiled set of observations, we recalibrate empirical relations between star formation rate density and the CO line ratios. Using SED fitting, we derived galaxy properties and performed galaxy stacking to combine the faint signals. In all cases, molecular gas masses were estimated using both tracers. We detected CO emission in three out of 12 galaxies and dust continuum emission in three of them. The obtained molecular gas masses indicate that most of these galaxies (${\mathrm{M}}_{\ast }<10^{10.7}$ ${\mathrm{M}}_{\odot }$) have lower molecular gas fractions and shorter depletion times compared to the expectations from established scaling relations at these redshifts. Several possible explanations for this gas deficit were explored, including uncertainties in mass estimates, effects of low metallicity environments, larger atomic gas reservoirs in low-mass systems, and the possibility that these represent low-mass analogs of "main sequence starburst" galaxies, which are undergoing sustained star formation due to gas compaction despite low overall gas fractions. We conclude that there is a molecular gas deficit at these mass and metallicity regimes. Our results suggest that this deficit is likely due to a significant amount of atomic gas, which our stacking indicates is about 91% of the total gas. However, this estimation might be an upper limit in the case of our galaxies containing CO-dark gas.

References in corpus (64)

• Stellar population synthesis at the resolution of 2003
• Galactic Stellar and Substellar Initial Mass Function
• Starburst99: Synthesis Models for Galaxies with Active Star Formation
• Cosmic Star Formation History
• A Simple Model for the Absorption of Starlight by Dust in Galaxies
• A Highly Consistent Framework for the Evolution of the Star-Forming "Main Sequence" from z~0-6
• CIGALE: a python Code Investigating GALaxy Emission
• Cool Gas in High Redshift Galaxies
• CASA, the Common Astronomy Software Applications for Radio Astronomy
• Dust Masses, PAH Abundances, and Starlight Intensities in the SINGS Galaxy Sample
• Gas-to-Dust mass ratios in local galaxies over a 2 dex metallicity range
• PHIBSS: Unified Scaling Relations of Gas Depletion Time and Molecular Gas Fractions
• Combined CO & Dust Scaling Relations of Depletion Time and Molecular Gas Fractions with Cosmic Time, Specific Star Formation Rate and Stellar Mass
• A Dust-Obscured Massive Maximum-Starburst Galaxy at a Redshift of 6.34
• The CO-to-H2 Conversion Factor From Infrared Dust Emission Across the Local Group
• xCOLD GASS: the complete IRAM-30m legacy survey of molecular gas for galaxy evolution studies
• ISM masses and the star formation law at Z = 1 to 6 // ALMA observations of dust continuum in 145 galaxies in the COSMOS survey field
• The Evolution of the Star-forming Interstellar Medium across Cosmic Time
• A Two-Parameter Model for the Infrared/Submillimeter/Radio Spectral Energy Distributions of Galaxies and AGN
• The metallicity dependence of the CO {\rightarrow} H_2 conversion factor in z>1 star forming galaxies
• CO excitation of normal star forming galaxies out to z=1.5 as regulated by the properties of their interstellar medium
• The Evolution of ISM Mass Probed by Dust Emission -- ALMA Observations at z = 0.3 to 2
• The MOSDEF Survey: The Evolution of the Mass-Metallicity Relation from $z=0$ to $z\sim 3.3$
• Validation of the equilibrium model for galaxy evolution to z~3 through molecular gas and dust observations of lensed star-forming galaxies
• Low CO Luminosities in Dwarf Galaxies
• The [C II] emission as a molecular gas mass tracer in galaxies at low and high redshift
• The molecular gas in Luminous Infrared Galaxies I: CO lines, extreme physical conditions, and their drivers
• Multi-scale cluster lens mass mapping I. Strong Lensing modelling
• The cold interstellar medium of galaxies in the Local Universe
• Evolution of the atomic and molecular gas content of galaxies
• Tracing the total molecular gas in galaxies: [CII] and the CO-dark gas
• GOODS-Herschel~: Gas-to-dust mass ratios and CO-to-H_2 conversion factors in normal and starbursting galaxies at high-z
• Constraining the metallicities, ages, star formation histories, and ionizing continua of extragalactic massive star populations
• A Theory for the Excitation of CO in Star Forming Galaxies
• Zooming on the internal structure of $z\simeq 6$ galaxies
• A New Survey for Giant Arcs
• Subaru Weak Lensing Measurements of Four Strong Lensing Clusters: Are Lensing Clusters Over-Concentrated?
• The Sunburst Arc: Direct Lyman α escape observed in the brightest known lensed galaxy
• The Physical Conditions, Metallicity and Metal Abundance Ratios In a Highly Magnified Galaxy at z = 3.6252
• Molecular gas content in strongly-lensed z~1.5-3 star-forming galaxies with low IR luminosities
• Physical Characterization of an Unlensed Dusty Star-Forming Galaxy at $z=5.85$
• The ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: Evolution of the molecular gas in CO-selected galaxies
• Strong Lens Models for 37 Clusters of Galaxies from the SDSS Giant Arcs Survey
• Spatial variations in aromatic hydrocarbon emission in a dust-rich galaxy
• The Magellan Evolution of Galaxies Spectroscopic and Ultraviolet Reference Atlas (MEGaSaURA) I: The Sample and the Spectra
• The Sloan Bright Arcs Survey: Four Strongly Lensed Galaxies with Redshift >2
• Two Lensed z~3 Lyman Break Galaxies Discovered in the SDSS Giant Arcs Survey
• GOODS-ALMA 2.0: Starbursts in the main sequence reveal compact star formation regulating galaxy evolution prequenching
• Direct measurement of the [CI] luminosity to molecular gas mass conversion factor in high-redshift star-forming galaxies
• VALES: II. The physical conditions of interstellar gas in normal star-forming galaxies up to z=0.2 revealed by ALMA
• CO Emission, Molecular Gas, and Metallicity in Main-Sequence Star-Forming Galaxies at $z\sim 2.3$
• The Cosmic Telescope that Lenses the Sunburst Arc, PSZ1 G311.65-18.48: Strong Gravitational Lensing model and Source Plane Analysis
• VLA Legacy Survey of Molecular Gas in Massive Star-forming Galaxies at High Redshift
• On the lack of correlation between Mg II 2796, 2803 Angstrom and Lyman alpha emission in lensed star-forming galaxies
• Neutral carbon and highly excited CO in a massive star-forming main sequence galaxy at z=2.2
• Discovery of a Very Bright and Intrinsically Very Luminous, Strongly Lensed Lyα Emitting Galaxy at z = 2.82 in the BOSS Emission-Line Lens Survey
• Spatially Resolved Outflows in a Seyfert Galaxy at z = 2.39
• What Controls the Star Formation in Luminous Starburst Mergers ?
• The `Cosmic Seagull': a highly magnified disk-like galaxy at z~2.8 behind the Bullet Cluster
• Molecular gas properties of Q1700-MD94: a massive, main-sequence galaxy at $z\approx 2$
• Molecular gas budget and characterization of intermediate-mass star-forming galaxies at $z\approx 2-3$
• Molecular Gas Properties in the Host Galaxy of GRB080207
• Jansky Very Large Array detections of CO(1-0) emission in HI-absorption-selected galaxies at $z\gtrsim 2$
• CO Excitation in High-z Main Sequence Analogues: Resolved CO(4-3)/CO(3-2) Line Ratios in DYNAMO Galaxies

Cited by in corpus (1)

• The [C II] line emission as an interstellar medium probe in the MARIGOLD galaxies