SDSS-IV MaNGA: Evidence of the importance of AGN feedback in low-mass galaxies

TL;DR

This study provides new evidence of active galactic nucleus (AGN) feedback in low-mass, quenched galaxies, highlighting its role in galaxy evolution and quenching processes through spatially resolved spectroscopy.

Contribution

First detection of AGN feedback in low-mass galaxies using MaNGA data, revealing ionised gas kinematics and potential outflows in this mass range.

Findings

6 galaxies with active AGN preventing star formation

Ionised gas kinematically offset from stars in 5 galaxies

Evidence of residual star formation or no gas in others

Abstract

We present new evidence for AGN feedback in a subset of 69 quenched low-mass galaxies ($M_{\star} \lesssim 5\times10^{9}$ M$_{\odot}$, $M_{\rm{r}} > -19$) selected from the first two years of the SDSS-IV MaNGA survey. The majority (85 per cent) of these quenched galaxies appear to reside in a group environment. We find 6 galaxies in our sample that appear to have an active AGN that is preventing on-going star-formation; this is the first time such a feedback mechanism has been observed in this mass range. Interestingly, five of these six galaxies have an ionised gas component that is kinematically offset from their stellar component, suggesting the gas is either recently accreted or outflowing. We hypothesise these six galaxies are low-mass equivalents to the "red geysers" observed in more massive galaxies. Of the other 63 galaxies in the sample, we find 8 do appear for have some low-level, residual star formation, or emission from hot, evolved stars. The remaining galaxies in our sample have no detectable ionised gas emission throughout their structures, consistent with them being quenched. This work shows the potential for understanding the detailed physical properties of dwarf galaxies through spatially resolved spectroscopy.