Evidence of Gas Depletion in Quasars with Moderate Radio Emission

Abstract The energy released by active galactic nuclei (AGNs) is considered to have a profound impact on the cold gas properties of their host galaxies, potentially heating or removing the gas and further suppressing star formation. To understand the feedback from AGN radio activity, we investigate its impacts on the cold gas reservoirs in AGNs with different radio activity levels. We construct a quasar sample with a mean z ∼ 1.5 and a mean L bol ∼ 10 45.8 erg s −1 , all with Herschel detections to enable estimates of the total gas mass through the galactic dust continuum emission. The sample is then crossmatched with radio catalogs and divided into radio-loud quasars, radio-detected radio-quiet (RQ) quasars, and radio-undetected quasars based on their radio loudness. Through spectral energy distribution fitting, we find the radio-detected RQ quasars exhibit evidence of gas deficiency with host galaxies possessing ∼0.3 dex lower dust and gas masses compared to the other two groups, despite being matched in M BH , L bol , M *, and star formation rate. Furthermore, evidence from optical spectra shows that both the fraction and velocity of outflows are higher in the radio-detected RQ group, suggesting a connection between the ionized gas outflows and the moderate radio activity. These results suggest that the AGN feedback could be more efficient in AGNs with weak/moderate radio emission than in those without radio detection or those with strong radio emission. Further high-resolution observations are needed to understand the interaction between the interstellar medium and the weak/moderate AGN radio activity.