Evidence for depleted gas reservoirs in the most luminous unobscured quasars at cosmic noon

Over the last decade, ALMA observations have constrained the molecular gas content of diverse samples of AGN host galaxies in the high-z Universe. Despite this, it has been difficult to get a clear consensus as to whether AGN hosts at high-z have lower molecular gas content as a result of strong feedback and large statistical samples are still missing in the literature. However, in our recent study of 41 of the most luminous, unobscured quasars at z ∼ 2 we find universally low gas fractions in the entire sample relative to both obscured/red quasars and SFGs of similar luminosity at the same redshift. I will present evidence for a correlation between the gas fractions and obscuration that would be consistent with an evolutionary sequence from a gas-rich, dusty quasar to a gas-poor, unobscured quasar. I will also present tentative trends linking the gas fractions and the broad-line region (BLR) properties, with quasars showing stronger BLR winds having higher gas fractions.