Radio sources and environmental effects in E and S0 galaxies

Samples of elliptical and lenticular galaxies are analyzed to study the effect of the large scale environment, measured through an unbiased estimator, and the effect of the small scale (~100kpc) environment on the radio emission. It is found that while the membership of an E or S0 galaxy to a group or a cluster has no effect on the probability to be a radio source, an excess of close companions is present around galaxies with a high radio to optical emission ratio, confirming previous results by Heckman et al. (1985).