Ionized Gas Outflows in the Galaxy And Mass Assembly (GAMA) Survey: Signatures of AGN Feedback in Low-Mass Galaxies

TL;DR

This study identifies ionized gas outflows in 398 GAMA survey galaxies, highlighting that low-mass galaxies with AGNs exhibit faster outflows, suggesting AGN feedback impacts galaxy evolution even in low-mass systems.

Contribution

It provides the first systematic analysis of ionized gas outflows in low-mass galaxies, demonstrating AGN feedback effects in galaxies with stellar masses below 10^10 solar masses.

Findings

Outflows are faster in AGNs than in star-forming galaxies.

Low-mass AGNs show faster, more blueshifted outflows.

AGN feedback influences low-mass galaxy evolution.

Abstract

We present a sample of 398 galaxies with ionized gas outflow signatures in their spectra from the Galaxy and Mass Assembly (GAMA) Survey Data Release 4, including 45 low-mass galaxies with stellar masses $M_*<10^{10}$ $M_\odot$. We assemble our sample by systematically searching for the presence of a second velocity component in the [O III]$\lambda\lambda 4959, 5007$ doublet emission line in 39,612 galaxies with redshifts $z<0.3$. The host galaxies are classified using the BPT diagram, with $\sim$89% identified as AGNs and composites and 11% as star-forming (SF) galaxies. The outflows are typically faster in AGNs with a median velocity of 936 km s$^{-1}$ compared to 655 km s$^{-1}$ in the SF objects. Of particular interest are the 45 galaxies in the low-mass range, of which a third are classified as AGNs/composites. The outflows from the low-mass AGNs are also faster and more blueshifted compared to those in the low-mass SF galaxies. This indicates that black hole outflows can affect host galaxies in the low-mass range and that AGN feedback in galaxies with $M_*<10^{10}$ $ M_\odot$ should be considered in galaxy evolution models.