The Limited Impact of Outflows: Integral-Field Spectroscopy of 20 Local AGNs

Abstract

To investigate AGN outflows as a tracer of AGN feedback on star-formation, we perform integral-field spectroscopy of 20 type 2 AGNs at z<0.1, which are luminous AGNs with the [O III] luminosity >10$^{41.5}$ erg/s, and exhibit strong outflow signatures in the [O III] kinematics. By decomposing the emission-line profile, we obtain the maps of the narrow and broad components of [O III] and H$\alpha$ lines, respectively. The broad components in both [O III] and H$\alpha$ represent the non-gravitational kinematics, i.e., gas outflows, while the narrow components, especially in H$\alpha$, represent the gravitational kinematics, i.e., rotational disk. By using the integrated spectra within the flux-weighted size of the narrow-line region, we estimate the energetics of the gas outflows. The ionized gas mass is 1.0-38.5$\times 10^5$ $M_{\odot}$, and the mean mass outflow rate is 4.6$\pm$4.3 $M_{\odot}$/yr, which is a factor of ~260 higher than the mean mass accretion rate 0.02$\pm$0.01 $M_{\odot}$/yr. The mean energy injection rate of the sample is 0.8$\pm$0.6% of the AGN bolometric luminosity, while the momentum flux is (5.4$\pm$3.6)$\times$ $L_{bol}$/c on average, except for two most kinematically energetic AGNs with low $L_{bol}$, which are possibly due to the dynamical timescale of the outflows. The estimated outflow energetics are consistent with the theoretical expectations for energy-conserving outflows from AGNs, yet we find no supporting evidence of instantaneous quenching of star formation due to the outflows.