Red quasars blow out molecular gas from galaxies during the peak of cosmic star formation

TL;DR

This study provides direct observational evidence linking dust-reddening and molecular outflows in high-redshift quasars, demonstrating that quasar radiation pressure can expel gas and influence galaxy evolution during peak star formation.

Contribution

It presents the first direct link between dust-reddening and molecular outflows in $z\,\sim2.5$ quasars, confirming radiative feedback's role in ejecting gas from galaxy nuclei.

Findings

Detected molecular outflows with velocities 500--1000 km/s.

Outflows occur only when quasar radiation pressure is sufficient.

Molecules survive in outflows from luminous quasars.

Abstract

Recent studies have suggested that red quasars are a phase in quasar evolution when feedback from black hole accretion evacuates obscuring gas from the nucleus of the host galaxy. Here, we report a direct link between dust-reddening and molecular outflows in quasars at $z\sim2.5$. By examining the dynamics of warm molecular gas in the inner region of galaxies, we detect outflows with velocities 500--1000 km s$^{-1}$ and infer timescales of $\approx0.1$ Myr that are due to ongoing quasar energy output. We observe outflows only in systems where quasar radiation pressure on dust in the vicinity of the black hole is sufficiently large to expel their obscuring gas column densities. This result is in agreement with theoretical models that predict radiative feedback regulates gas in the nuclear regions of galaxies and is a major driving mechanism of galactic-scale outflows of cold gas. Our findings suggest that radiative quasar feedback ejects star-forming gas from within nascent stellar bulges at velocities comparable to those seen on larger scales, and that molecules survive in outflows even from the most luminous quasars.