CO spectra of the ISM in the Host Galaxies of the Most Luminous WISE-Selected AGNs

TL;DR

This study investigates the molecular gas properties in the host galaxies of the most luminous WISE-selected AGNs, revealing turbulence, outflows, and merger signatures through CO emission line observations, highlighting AGN feedback effects.

Contribution

First detailed mid-J CO line observations of Hot DOGs showing turbulence, outflows, and merger evidence, advancing understanding of molecular gas in luminous obscured AGNs.

Findings

Broad CO lines indicate turbulent molecular ISM.

Molecular outflows extend up to 5 kpc.

High CO(4-3) to CO(1-0) luminosity ratios suggest underluminous low-excitation CO.

Abstract

We present observations of mid-J J=4-3 or J=5-4 carbon monoxide (CO) emission lines and continuum emission from a sample of ten of the most luminous log(L/L_solar)~14 Hot Dust-Obscured Galaxies (Hot DOGs) discovered by the Wide-field Infrared Survey Explorer (WISE) with redshifts up to 4.6. We uncover broad spectral lines (FWHM~400 km/s) in these objects, suggesting a turbulent molecular interstellar medium (ISM) may be ubiquitous in Hot DOGs. A halo of molecular gas, extending out to a radius of 5 kpc is observed in W2305-0039, likely supplied by 940 km/s molecular outflows. W0831+0140 is plausibly the host of a merger between at least two galaxies, consistent with observations made using ionized gas. These CO(4-3) observations contrast with previous CO(1-0) studies of the same sources: the CO(4-3) to CO(1-0) luminosity ratios exceed 300 in each source, suggesting that the lowest excited states of CO are underluminous. These findings show that the molecular gas in Hot DOGs is consistently turbulent, plausibly a consequence of AGN feedback, triggered by galactic mergers.