Deciphering the imprint of AGN feedback in Seyfert galaxies: Nuclear-scale molecular gas deficits

Abstract

We use a sample of 64 nearby (D=7-45 Mpc) disk galaxies including 45 AGN and 19 non-AGN, that have high spatial resolution multiline CO observations obtained with the ALMA and/or PdBI arrays to study the distribution of cold molecular gas in their circumunuclear disks (CND). We analyze whether the concentration of cold molecular gas changes as a function of the X-ray luminosity in the 2-10 keV range ($L_{\mathrm{X}}$). We also study the concentration of the hot molecular gas using NIR data obtained for the H2 1-0S(1) line. We find a turnover in the distribution of the cold molecular gas concentration as a function of $L_{\mathrm{X}}$ with a breakpoint which divides the sample into two branches: the AGN build-up branch ($L_{\mathrm{X}}\le 10^{41.5\pm 0.3}$erg/s) and the AGN feedback branch ($L_{\mathrm{X}}\ge 10^{41.5\pm 0.3}$erg/s) . Lower luminosity AGN and non-AGN of the AGN build-up branch show high cold molecular gas concentrations and centrally peaked radial profiles on nuclear ($r\le 50$~pc) scales. Higher luminosity AGN of the AGN feedback branch, show a sharp decrease in the concentration of molecular gas and flat or inverted radial profiles. The cold molecular gas concentration index ($CCI$), defined as the ratio of surface densities at $r\le 50$~pc and $r\le 200$~pc , namely $CCI\equiv$~log${}_{10}(\hat{I}{\pounds }_{50}^{\mathrm{gas}}/\hat{I}{\pounds }_{200}^{\mathrm{gas}}$), spans a factor ~4-5 between the galaxies lying at the high end of the AGN build-up branch and the galaxies of the AGN feedback branch. The concentration and radial distributions of the hot molecular gas in our sample follow less extreme trends as a function of the X-ray luminosity. These observations confirm, on a three times larger sample, previous evidence found by the GATOS survey that the imprint of AGN feedback on the CND-scale distribution of molecular gas is more extreme in higher luminosity Seyfert galaxies of the local universe.

Accepted by Astronomy & Astrophysics (A&A) (14/06/2024), 26 pages, 16 figures