Outflow and metallicity in the broad-line region of low-redshift active galactic nuclei

TL;DR

This study analyzes UV spectra of low-redshift AGNs to explore the relationship between outflow strength, metallicity, and accretion activity, revealing similarities with high-redshift quasars and implications for galaxy evolution.

Contribution

It provides new insights into the connection between BLR outflows, metallicity, and accretion rates in low-redshift AGNs, extending previous high-redshift findings.

Findings

Outflow strength depends on Eddington ratio.

BLR metallicity correlates with outflow activity.

Results suggest a link between outflows, star formation, and SMBH growth.

Abstract

Outflows in active galactic nuclei (AGNs) are crucial to understand in investigating the co-evolution of supermassive black holes (SMBHs) and their host galaxies since outflows may play an important role as an AGN feedback mechanism. Based on the archival UV spectra obtained with HST and IUE, we investigate outflows in the broad-line region (BLR) in low-redshift AGNs (z < 0.4) through the detailed analysis of the velocity profile of the CIV emission line. We find a dependence of the outflow strength on the Eddington ratio and the BLR metallicity in our low-redshift AGN sample, which is consistent with the earlier results obtained for high-redshift quasars. These results suggest that the BLR outflows, gas accretion onto SMBH, and past star-formation activity in the host galaxies are physically related in low-redshift AGNs as in powerful high-redshift quasars.