Spectroscopic study of the broad component of [O III]{\lambda}5007 profile in type 1 AGNs

TL;DR

This study analyzes the properties of broad [O III] emission lines in type 1 AGNs to understand their relation to black hole mass and accretion activity, revealing correlations and potential outflow signatures.

Contribution

It provides a systematic analysis of broad [O III] components in a large AGN sample, exploring their connection to black hole properties and outflow indicators.

Findings

Strong correlation between blue emission and black hole mass when using line width as a surrogate.

Correlation weakens when using virial black hole mass estimates.

Velocity shifts between broad and core components weakly correlate with Eddington ratio.

Abstract

The spectra of type 1 active galactic nuclei (AGNs) often exhibit broad component in [O III]$\lambda$5007, which are typically blue-shifted and associated with strong outflows. We systematically analyze the [O III] emission-line properties of type 1 AGNs with broad components to investigate how these kinematic features relate to the physical properties of the central engine. From a parent sample of 11,557 QSOs at $z<0.3$ in Data Release 16 of the Sloan Digital Sky Survey, we select 2,290 type 1 AGNs exhibiting broad components in [O III]. Previous studies have reported a strong correlation between the blue emission, defined as the full extent of the broad component on the blue side, and black hole mass when the latter is estimated from the $M_{\rm BH}$--$\sigma_{\ast}$ relation using the line width $\sigma$ of the [O III] core component as a surrogate for $\sigma_{\ast}$. By the same way, the black hole mass also shows a strong correlation with the blue emission parameter in our sample. However, this correlation becomes negligible when virial black hole masses are adopted. Besides, the velocity shifts between the broad and core components of [O III] show a weak correlation with the Eddington ratio. This is consistent with the expectation that higher accretion rates enhance radiative pressure, thereby driving faster or more prominent outflows. In future work, we will compare [O III] broad component properties between typical type 1 AGNs and those with double-peaked [O III] to probe differences in narrow-line region kinematics and the impact of outflows or dual AGNs.