LINER galaxy properties and the local environment
  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.
