Exploring the Fundamental Mechanism in Driving Highest-Velocity Ionized Outflows in Radio AGNs

Abstract

We investigate the ionized gas kinematics relationship with X-ray, radio and accreting properties using a sample of 348 nearby (z<0.4) SDSS-FIRST-X-ray detected AGNs. X-ray properties of our sample are obtained from XMM-Newton, Swift and Chandra observations. We unveil the ionized gas outflows in our sample manifested by the non-gravitational broad component in [O III]lambda 5007 angstrom emission line profiles. From the comparison of the correlation of non-parametric outflow velocities (i.e., the velocity width, the maximal velocity of outflow and line dispersion) with X-ray luminosity and radio luminosity, we find that outflow velocities have similarly positive correlations with both X-ray and radio luminosity. After correcting for the gravitational component, we find that the [O III] velocity dispersion normalized by stellar mass also increases with both X-ray luminosity and radio luminosity. We also find that, for a given X-ray (radio) luminosity, radio (X-ray) luminous AGNs have higher outflow velocities than non-radio (non-X-ray) luminous AGNs. Therefore, we find no clear preference between X-ray luminosity and radio luminosity in driving high-velocity ionized outflows and conclude that both AGN activity and small-scale jets contribute comparably. Moreover, there is no evidence that our obscured AGNs are preferentially associated with higher velocity outflows. Finally, we find a turning point around log(lambda(Edd)) similar or equal to -1.3 when we explore the dependency of outflow velocity on Eddington ratio. It can be interpreted considering the role of high radiation pressure (log(lambda(Edd)) greater than or similar to -1.3) in causing drastic reduction in the covering factor of the circumnuclear materials.