Environment and Gas Fraction in Type 2 AGN versus Non-AGN Galaxies

Abstract We investigate the environmental parameters and gas fraction ( f gas ) properties of type 2 active galactic nuclei (AGN) and non-AGN galaxies, utilizing a large sample of galaxies from the Sloan Digital Sky Survey DR7 with z ≤ 0.3. We find that the environment affects type 2 AGN and non-AGN galaxies in similar ways and does not impact the strength of AGN-driven outflows. The f gas of type 2 AGN and non-AGN host galaxies show no variation between group and isolated environments, suggesting that host galaxy gas content is largely independent of large-scale environment. We find that type 2 AGN host galaxies possess systematically lower f gas than their non-AGN counterparts when matched in stellar mass and star formation rate (SFR). This suggests that AGN activity plays a significant role in regulating the molecular gas reservoir and, consequently, the star formation processes within galaxies. We find that type 2 AGNs exhibiting strong outflows are associated with higher gas fractions, higher SFRs, and younger stellar populations than those with weak or no outflows. This may indicate either concurrent star formation in gas-rich systems hosting powerful outflows, or a time delay between AGN activity and its effect on star formation consistent with a delayed AGN feedback scenario.