AGN and Dwarf Galaxy Gas Kinematics

TL;DR

This study investigates how active galactic nuclei (AGN) influence gas kinematics and star formation in dwarf galaxies, revealing a strong link between AGN activity and disturbed gas dynamics, including counter-rotation and potential star formation suppression.

Contribution

It provides the first detailed comparison of gas kinematics in dwarf galaxies with and without AGN, demonstrating AGN's role in disturbing gas and affecting galaxy evolution.

Findings

73% of AGN-hosting dwarf galaxies have disturbed gas.

All galaxies with counter-rotating gas contain AGN.

AGN-hosting galaxies often fall below the stellar-halo mass relation.

Abstract

We present spatially resolved kinematic measurements of stellar and ionized gas components of dwarf galaxies in the stellar mass range $10^{8.5} - 10^{10} M_{\odot}$, selected from SDSS DR7 and DR8 and followed-up with Keck/LRIS spectroscopy. We study the potential effects of active galactic nuclei (AGN) on galaxy-wide gas kinematics by comparing rotation curves of 26 galaxies containing AGN, and 19 control galaxies with no optical or infrared signs of AGN. We find a strong association between AGN activity and disturbed gas kinematics in the host galaxies. While star forming galaxies in this sample tend to have orderly gas discs that co-rotate with the stars, 73\% of the AGN have disturbed gas. We find five out of 45 galaxies have gaseous components in counter-rotation with their stars, and all galaxies exhibiting counter-rotation contain AGN. Six out of seven isolated galaxies with disturbed ionized gas host AGN. At least three AGN fall clearly below the stellar-halo mass relation, which could be interpreted as evidence for ongoing star formation suppression. Taken together, these results provide new evidence supporting the ability of AGN to influence gas kinematics and suppress star formation in dwarf galaxies. This further demonstrates the importance of including AGN as a feedback mechanism in galaxy formation models in the low-mass regime.