The optical properties of low redshift radio galaxies

We present morphological and photometric properties of 79 low redshift (z l ess than or equal to 0.12) radio galaxies extracted from two radio flux lim ited samples of radio sources. All objects are imaged in the R band and for a subsample we have also obtai ned B band images. The sample includes sources of both FRI and FRII radio m orphological type. Through the decomposition of the luminosity profiles and the analysis of the structural profiles (ellipticity, PA, c4) of the galax ies we are able to characterize in detail the optical properties of the rad io galaxies. It is found that most of host galaxies are luminous bulge dominated systems similar to normal giant ellipticals. Some cases of additional disk compone nts are found whose spheroid-to-disk luminosity ratio is similar to that fo und in SO galaxies. The average absolute magnitude is < M-HOST.(tot)> -24.0 with a clear trend for FRI sources to be similar to 0.5 mag brighter than FRII galaxies. In about 40% of the objects observed we find an excess of light in the nucl eus that is attributed to the presence of a nuclear point source whose lumi nosity is on average similar to 1-2% of the total flux of the host galaxy. The luminosity of these nuclear point sources appears correlated with the c ore radio power of the galaxies. Radio galaxies follow the same mu(e) - R-e relationship as normal elliptica l galaxies. The distribution of ellipticity, the amount of twisting and shape of isopho tes (bozy, disky) do not differ significantly from other ellipticals. The e vidence for recent interactions is therefore rather modest. Finally on average radio galaxies are bluer and have a color dispersion lar ger than normal elliptical galaxies, and the average color gradient in radi o galaxies appears slightly steeper than in normal ellipticals. These results support a scenario where radio emission is weakly related wit h the overall properties and/or the activity have negligible effects on the global characteristics of the host galaxy.