Outflowing Galactic Winds in Post-starburst and AGN Host Galaxies at 0.2<z<0.8

TL;DR

This study investigates outflowing galactic winds in intermediate-redshift galaxies hosting low-luminosity AGN or recently quenched star formation, finding winds are common but likely driven by supernovae rather than AGN, with limited impact on star formation.

Contribution

First detailed spectroscopic analysis of outflows in low-luminosity AGN and post-starburst galaxies at 0.2<z<0.8, highlighting wind properties and their potential origins.

Findings

60% of X-ray AGN hosts have outflows with ~200 km/s

31% of post-starburst galaxies show similar winds

Winds are likely driven by supernovae, not AGN

Abstract

We present Keck/LRIS-B spectra for a sample of ten AEGIS X-ray AGN host galaxies and thirteen post-starburst galaxies from SDSS and DEEP2 at 0.2<z<0.8 in order to investigate the presence, properties, and influence of outflowing galactic winds at intermediate redshifts. We focus on galaxies that either host a low-luminosity AGN or have recently had their star formation quenched to test whether these galaxies have winds of sufficient velocity to potentially clear gas from the galaxy. We find, using absorption features of Fe II, Mg II, and Mg I, that six of the ten (60%) X-ray AGN host galaxies and four of the thirteen (31%) post-starburst galaxies have outflowing galactic winds, with typical velocities of ~200 km/s. We additionally find that most of the galaxies in our sample show line emission, possibly from the wind, in either Fe II* or Mg II. A total of 100% of our X-ray AGN host sample (including four red sequence galaxies) and 77% of our post-starburst sample has either blueshifted absorption or line emission. Several K+A galaxies have small amounts of cool gas absorption at the systemic velocity, indicating that not all of the cool gas has been expelled. We conclude that while outflowing galactic winds are common in both X-ray low-luminosity AGN host galaxies and post-starburst galaxies at intermediate redshifts, the winds are likely driven by supernovae (as opposed to AGN) and do not appear to have sufficiently high velocities to quench star formation in these galaxies.