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

TL;DR

This study investigates ionized gas outflows in 348 nearby AGNs, revealing that both X-ray and radio luminosities similarly influence outflow velocities, with high radiation pressure potentially reducing circumnuclear material coverage.

Contribution

It demonstrates that both AGN activity and small-scale jets contribute equally to driving high-velocity ionized outflows, and explores the role of Eddington ratio in outflow dynamics.

Findings

Outflow velocities correlate positively with X-ray and radio luminosities.

Radio and X-ray luminous AGNs exhibit higher outflow velocities than less luminous ones.

A turning point at log(λ_Edd) ≈ -1.3 indicates radiation pressure impacts outflow properties.

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 [OIII] $\lambda$5007$\overset{\circ}{A}$. emission line profiles. From the comparison of the correlation of non-parametric outflow velocities (i.e., the velocity width, the maximal velocity of outflow and line dispersion) with X-ray luminosity and radio luminosity, we find that outflow velocities have similarly positive {correlations} with both X-ray and radio luminosity. After correcting for the gravitational component, we find that the [OIII] velocity dispersion normalized by stellar mass also increases with both X-ray luminosity and radio luminosity. We also find that for a given X-ray (radio) luminosity, radio (X-ray) luminous AGNs have higher outflow velocities than non-radio (non-X-ray) luminous AGNs. Therefore, we find no clear preference between X-ray luminosity and radio luminosity in driving high-velocity ionized outflows and conclude that both AGN activity and small-scale jets contribute comparably. Moreover, there is no evidence that our obscured AGNs are preferentially associated with higher velocity outflows. Finally, we find a turning point around log$(\lambda_{Edd}) \simeq -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$(\lambda_{Edd}) \gtrsim -1.3$) in drastic reduction in the covering factor of the circumnuclear materials.