2025/09/29 by Prajapati, Prachi, Riechers, Dominik, Cox, Pierre +20
#Astrophysics of Galaxies (astro-ph.GA) #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences
paper · doi:10.48550/arxiv.2509.25167
We present the first results of Vz-GAL, a high-redshift CO(J=1-0) large survey with the Karl G. Jansky Very Large Array, targeting 92 Herschel-selected, infrared-luminous, dusty star-forming galaxies (DSFGs) at redshifts 1 to 6. These sources are selected based on having redshifts and mid/high-J CO transitions from the NOrthern Extended Millimeter Array z-GAL survey. We successfully detect CO(J=1-0) emission in 90/92 galaxies at the expected positions and redshifts, including 9 tentative detections at 2σ- 3σ significance, and CO(J=2-1) emission in 10 of these galaxies. The CO(J=1-0) luminosities suggest apparent gas masses in the range μM\rm H2 = (2-20) × 1011~(αCO/4.0)~\mathrmM\odot, which implies gas depletion times of (50-600) Myr. These timescales show similar spread as local ULIRGs, suggesting a self-regulatory mechanism that maintains a consistent SFR per unit gas mass in starbursts across redshifts. To quantify the contribution of "excitation correction" factors to gas mass estimates, we calculate median CO line brightness temperature ratios of r21=0.88±0.25, r31=0.61±0.22, r41=0.49±0.15, r51=0.47±0.13, and r61=0.28±0.13. Accounting for these corrections results in a reduced scatter in 'gas mass-star formation rate' relations. We also find a median log(L′[CI](3P1 - 3P0)/L′CO(J=1-0))=-0.71±0.12 for a subsample of 23 sources, consistent with the ratios derived for local star-forming galaxies. Together, our findings are in agreement with common conditions in the cold gas reservoirs among star-forming galaxies over a broad range in star formation modes, efficiencies, and scales.