The B3-VLA Sample

Abstract

The use of radio sources to identify the most distant object in the Universe has been proved to be a very successful approach in observational cosmology. Studies of high flux, powerful 3CR and 1-Jy galaxies show dramatic evidence for color and luminosity evolution, reaching to look-back times 80% of the Hubble time. In order to disentangle the selection effect, correlation with redshift, and correlation with radio power, it is necessary to obtain well defined, complete samples of radio galaxies at a large range of redshifts, and with a wide baseline of radio power. We need the identifications of complete samples in the flux range of a factor 10 smaller than 3CR sample. The B3VLA sample (Vigotti et al. 1989) is a subset of 1050 sources selected in restricted areas at high galactic from the B3 survey, which is complete down to S(408 MHz)= 100mJy. For the B3VLA sample detailed VLA maps were obtained at 1.4GHz using A, C and D arrays. We are conducting a long-term effort to provide optical ID’s and redshifts for well-defined, complete subsamples of the B3VLA survey (Djorgovski et al. 1990, Vigotti et al. 1990, Thompson et al., 1994), a similar effort is being conducted independently by others. We present here the “status of the art” for the B3VLA sample: a new low flux sample of 124 QSS selected at meter wavelength, a sample of 194 radio galaxies (77 with measured redshift) and a sample of 732 Empty Fields (EF : no optical counterpart on POSS I plate).