LINER galaxy properties and the local environment

TL;DR

This study compares LINER galaxies with non-LINER galaxies across various environments, revealing LINERs are generally older, redder, and less influenced by local density, suggesting different evolutionary processes or ionization sources.

Contribution

It provides a comprehensive analysis of LINER properties across environments, highlighting their distinct stellar populations and challenging the typical morphology-density relation.

Findings

LINERs are redder and older than control galaxies across densities.

Most LINERs are consistently redder and older regardless of environment.

LINERs do not follow the typical morphology-density relation of galaxies.

Abstract

We analyse the properties of a sample of 5560 LINER galaxies selected from SDSS-DR12 at low redshift, for a complete range of local density environments. The host LINER galaxies were studied and compared with a well-defined control sample of 5553 non-LINER galaxies matched in red shift, luminosity, morphology and local density. By studying the distributions of galaxy colours and the stellar age population, we find that LINERs are redder and older than the control sample over a wide range of densities.In addition, LINERs are older than the control sample, at a given galaxy colour, indicating that some external process could have accelerated the evolution of the stellar population. The analysis of the host properties shows that the control sample exhibits a strong relation between colours, ages and the local density, while more than 90 per cent of the LINERs are redder and older than the mean values, independently of the neighbourhood density. Furthermore, a detailed study in three local density ranges shows that, while control sample galaxies are redder and older as a function of stellar mass and density, LINER galaxies mismatch the known morphology-density relation of galaxies without low-ionization features. The results support the contribution of hot and old stars to the low-ionization emission although the contribution of nuclear activity is not discarded.