Weak Galactic Winds in Active Galactic Nuclei Post-starburst Host Galaxies at z ~ 0.1

TL;DR

This study investigates galactic winds in post-starburst galaxies hosting active galactic nuclei at z ~ 0.1, revealing weak winds that are insufficient to expel significant gas, thus informing models of AGN feedback during galaxy evolution.

Contribution

It provides the first detailed measurement of wind velocities in AGN post-starburst galaxies, showing they are weaker than expected for effective gas expulsion, challenging certain feedback models.

Findings

AGN PSBs have higher wind velocities than control galaxies.

Winds are not powerful enough to remove significant halo gas.

Similar wind velocities are found in shocked and quenched PSBs.

Abstract

Post-starburst (PSB) galaxies may be in rapid transition from star-forming to quiescence and are excellent candidates to constrain active galactic nuclei (AGN) feedback models. We study galactic winds in the stacked spectrum of 560 AGN PSBs and that of a control sample of star-forming galaxies in the Sloan Digital Sky Survey (SDSS). Using a two component (inter-stellar +wind) absorption-line model of the \ion{Na}{i} doublet, and after accounting for the stellar photospheric absorption, we find that the AGN PSBs have a centroid wind velocity shift of $-252^{+64}_{-57}$ km s$^{-1}$ and a maximum blueshift velocity of $-678^{+54}_{-53}$ km s$^{-1}$. In comparison, the control sample, which is matched with the AGN PSBs in redshift, stellar mass, axis-ratio, the 4000 {\AA} break index, Balmer decrement, and WISE 12 $\mu$m to 4.6 $\mu$m flux ratio, has a centroid wind velocity shift of $-119^{+33}_{-41}$ km s$^{-1}$ and a maximum velocity of $-406^{+51}_{-61}$ km s$^{-1}$. The equivalent widths due to the winds in both samples are similar: $0.36^{+0.10}_{-0.07}$ {\AA} for the AGN PSBs and $0.24^{+0.07}_{-0.06} $ {\AA} for the control sample. Despite having a higher velocity, the observed winds in the AGN PSBs are still not powerful enough to sweep significant amounts of gas out of the halos of the host galaxies. We also detect winds of similar velocities in the stacked spectra of shocked and quenched PSBs.