The cold molecular gas regulates the activity of active galactic nuclei in massive galaxies

TL;DR

This study finds that molecular gas mass in massive galaxies is most strongly correlated with AGN activity indicators like radio and extit{O}III luminosity, suggesting it plays a key regulatory role.

Contribution

It demonstrates that molecular gas mass is the primary physical property linked to AGN activity, surpassing black hole, stellar, or bulge mass in correlation strength.

Findings

Radio and extit{O}III luminosities correlate strongly with molecular gas mass.

Controlling for molecular gas weakens correlations with other parameters.

Molecular gas mass may be the main driver of AGN activity.

Abstract

The physical quantities that directly regulate AGN feedback in massive galaxies remain poorly understood. Observations of molecular gas surrounding AGNs suggest that this gas serves as a fuel source for AGN activity. Accordingly, we study the relationship between AGN activity and molecular gas properties. In this study, we analyze a large sample of nearby AGNs with available measurements of molecular gas mass, radio luminosity, and \oiii~luminosity. Our results show that radio luminosity and \oiii~luminosity exhibit stronger correlations with molecular gas mass than with other physical parameters such as black hole mass, stellar mass, and bulge mass. Moreover, when controlling for the correlations between radio luminosity, \oiii~luminosity, and molecular gas mass, the relationships between these luminosities and other key physical parameters become significantly weaker or disappear entirely. This suggests that, of all the properties we have considered, it is the molecular gas mass that is most tightly correlated with radio and \oiii~luminosity, and may thus be the most important driver of nuclear activity.