Occurrence of LINER galaxies within the galaxy group environment

TL;DR

This study investigates the distribution of LINER galaxies within galaxy groups, revealing they are more common in low-density environments and do not follow typical morphology-density relations, suggesting environmental influences on LINER activity.

Contribution

It provides the first large-scale analysis of LINER occurrence relative to galaxy group environments, highlighting their preference for low-density regions and challenging existing morphology-density paradigms.

Findings

LINER galaxies are more prevalent in low-density environments.

LINER occurrence is about twice as high in poor groups compared to rich groups.

LINER hosts do not follow the typical morphology-density relation in high-mass groups.

Abstract

We study the properties of a sample of 3967 LINER galaxies selected from SDSS-DR7, respect to their proximity to galaxy groups. The host galaxies of LINER have been analysed and compared with a well defined control sample of 3841 non-LINER galaxies matched in redshift, luminosity, colour, morphology, age and stellar mass content. We find no difference between LINER and control galaxies in terms of colour and age of stellar population as function of the virial mass and distance to the geometric centre of the group. However, we find that LINER are more likely to populate low density environments in spite of their morphology, which is typical of high density regions such as rich galaxy clusters. For rich (poor) galaxy groups, the occurrence of LINER is $\sim$2 times lower (higher) than the occurrence of matched, non-LINER galaxies. Moreover, LINER hosts do not seem to follow the expected morphology-density relation in groups of high virial mass. The high frequency of LINERS in low density regions could be due to the combination of a sufficiently ample gas reservoir to power the low ionization emission and/or enhanced galaxy interaction rates benefiting the gas flow toward their central regions.