On the local radio luminosity function of galaxies

We cross-correlate the galaxies brighter than mB = 18 in the Virgo cluster with the radio sources in the NVSS survey (1.4 GHz), resulting in 180 radio-optical identifications. We determine the radio luminosity function of the Virgo galaxies, separately for the earlyand late-types. Late-type galaxies develop radio sources with a probability proportional to their optical luminosity. In fact their radio/optical (RB) distribution is gaussian, centered at logRB ∼ −0.5, i.e. the radio luminosity is ∼ 0.3 of the optical one. The probability of late-type galaxies to develop radio sources is almost independent of their detailed Hubble type, except for Sa (and S0+S0a) which are a factor of ∼ 5 less frequent than later types at any RB . Giant elliptical galaxies feed “monster” radio sources with a probability strongly increasing with mass. However the frequency of fainter radio sources is progressively less sensitive on the system mass. The faintest giant E galaxies (MB = −17) have a probability of feeding low power radio sources similar to that of dwarf E galaxies as faint as MB = −13.