AMIGA project: Quantification of the isolation of 950 CIG galaxies
  The role of the environment on galaxy evolution is still not fully
understood. In order to quantify and set limits on the role of nurture one must
identify and study a sample of isolated galaxies. The AMIGA project "Analysis
of the Interstellar Medium of Isolated GAlaxies" is doing a multi-wavelength
study of a large sample of isolated galaxies in order to examine their
interstellar medium and star formation activity. We processed data for 950
galaxies from the Catalogue of Isolated Galaxies (CIG, Karachentseva 1973) and
evaluated their isolation using an automated star-galaxy classification
procedure (down to M_B ~17.5) on large digitised POSS-I fields surrounding each
isolated galaxy (within a projected radius of at least 0.5 Mpc). We defined,
compared and discussed various criteria to quantify the degree of isolation for
these galaxies: e.g. Karachentseva's revised criterion, local surface density
computations, estimation of the external tidal force affecting each isolated
galaxy. We found galaxies violating Karachentseva's original criterion, and we
defined various subsamples of galaxies according to their degree of isolation.
Additionally, we sought for the redshifts of the primary and companion galaxies
to access the radial dimension. We also applied our pipeline to triplets,
compact groups and clusters and interpret the isolated galaxy population in
light of these control samples.
