BAT AGN Spectroscopic Survey -- XIX: Type 1 versus Type 2 AGN dichotomy from the point of view of ionized outflows

TL;DR

This study analyzes ionized outflows in approximately 650 AGN, revealing their occurrence rates and velocities across different types and luminosities, highlighting a higher incidence in less obscured AGN and a dependence on accretion rates.

Contribution

It provides the first detailed analysis of low-luminosity AGN outflows and their relation to AGN type and accretion properties using optical spectroscopy from the BAT survey.

Findings

Higher outflow occurrence in type 1.9 and type 1 AGN.

Outflows are predominantly blueshifted in type 1 and 1.9 AGN.

Outflow incidence correlates with high Eddington ratios.

Abstract

We present a detailed study of ionized outflows in a large sample of ~650 hard X-ray detected AGN. Using optical spectroscopy from the BAT AGN Spectroscopic Survey (BASS) we are able to reveal the faint wings of the [OIII] emission lines associated with outflows covering, for the first time, an unexplored range of low AGN bolometric luminosity at low redshift (z~0.05). We test if and how the incidence and velocity of ionized outflow is related to AGN physical parameters: black hole mass, gas column density, Eddington Ratio, [OIII], X-ray, and bolometric luminosities. We find a higher occurrence of ionized outflows in type 1.9 (55%) and type 1 AGN (46%) with respect to type 2 AGN (24%). While outflows in type 2 AGN are evenly balanced between blue and red velocity offsets with respect to the [OIII] narrow component, they are almost exclusively blueshifted in type 1 and type 1.9 AGN. We observe a significant dependence between the outflow occurrence and accretion rate, which becomes relevant at high Eddington ratios (> -1.7). We interpret such behaviour in the framework of covering factor-Eddington ratio dependence. We don't find strong trends of the outflow maximum velocity with AGN physical parameters, as an increase with bolometric luminosity can be only identified when including samples of AGN at high luminosity and high redshift taken from literature.