Occurrence of LINER galaxies within the galaxy group environment
  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.
