A census of ionized gas outflows in type 1 AGNs: gas outflows in AGNs. V

TL;DR

This study systematically analyzes ionized gas outflows in ~5000 Type 1 AGNs using [O III] emission line kinematics, revealing outflow signatures are more common at higher luminosities and Eddington ratios, driven mainly by radiation pressure.

Contribution

It provides the first large-scale, comparative analysis of gas outflows in Type 1 and Type 2 AGNs, highlighting the role of radiation pressure and orientation effects.

Findings

89% of Type 1 AGNs show double Gaussian [O III] profiles.

Blueshifted [O III] is 3.6 times more common than redshifted in Type 1 AGNs.

Outflow signatures increase with luminosity and Eddington ratio.

Abstract

We present a systematic study of ionized gas outflows based on the velocity shift and dispersion of the [O III] {\lambda}5007 $\AA$ emission line, using a sample of ~ 5000 Type 1 AGNs at z < 0.3 selected from Sloan Digital Sky Survey. This analysis is supplemented by the gas kinematics of Type 2 AGNs from Woo et al. (2016). For the majority of Type 1 AGNs (i.e., ~ 89%), the [O III] line profile is best represented by a double Gaussian model, presenting the kinematic signature of the non-virial motion. Blueshifted [O III] is more frequently detected than redshifted [O III] by a factor of 3.6 in Type 1 AGNs, while the ratio between blueshifted to redshifted [O III] is only 1.08 in Type 2 AGNs due to the projection and orientation effect. The fraction of AGNs with outflow signatures is found to increase steeply with [O III] luminosity and Eddington ratio, while Type 1 AGNs have larger velocity dispersion and more negative velocity shift than Type 2 AGNs. The [O III] velocity - velocity dispersion (VVD) diagram of Type 1 AGNs expands towards higher values with increasing luminosity and Eddington ratio, suggesting that the radiation pressure or wind is the main driver of gas outflows, as similarly found in Type 2 AGNs. In contrast, the kinematics of gas outflows is not directly linked to the radio activity of AGN.