Large scale correlations in gas traced by MgII absorbers around low mass galaxies

TL;DR

This study investigates large-scale gas correlations around low mass galaxies using MgII absorbers, revealing significant excesses and the influence of nearby radio-loud AGN on gas properties out to several megaparsecs.

Contribution

It provides the first large-scale statistical analysis of MgII absorbers around low mass galaxies, highlighting the impact of AGN feedback on gas distribution.

Findings

Excess MgII absorbers around low mass galaxies up to 10 Mpc.

MgII absorber properties are affected by nearby radio-loud AGN.

Significant large-scale correlations in gas traced by MgII absorbers.

Abstract

The physical origin of the large-scale conformity in the colours and specific star formation rates of isolated low mass central galaxies and their neighbours on scales in excess of 1 Mpc is still under debate. One possible scenario is that gas is heated over large scales by feedback from active galactic nuclei (AGN), leading to coherent modulation of cooling and star formation between well-separated galaxies. In this Letter, the metal line absorption catalogue of Zhu & Menard (2013) is used to probe gas out to large projected radii around a sample of a million galaxies with stellar masses ~10^{10} M_{sun} and photometric redshifts in the range 0.4<z<0.8 selected from Sloan Digital Sky Survey imaging data. This galaxy sample covers an effective volume of 2.2 Gpc^3. A statistically significant excess of MgII absorbers is present around the red low mass galaxies compared to their blue counterparts out to projected radii of 10 Mpc. In addition, the equivalent width distribution function of MgII absorbers around low mass galaxies is shown to be strongly affected by the presence of a nearby (R_p<2 Mpc) radio-loud AGN out to projected radii of 5 Mpc.