High-redshift radio galaxies from the Molonglo catalogue

Abstract

We report the result of radio and optical observations of a sample of southern hemisphere radio galaxies, selected from the Molonglo Reference Catalogue. The source were selected to have 408 MHz flux densities greater than 0.9 Jy and low-frequency spectral indices steeper than -0.9 VLA 6 cm maps and optical identifications of 13 sources are presented. All of these sources are indentified with faint galaxies, many of which have extended optical structures with morphologies characteristics od high redshift (Z > 0.8) radio galaxies. Long - slit spectroscopic observation have yielded redshifts for 11 of the galaxies, 5 of which are at Z > 2. The most distant source in the present sample, 0316 - 257, has a redshift of 3.13, while the median redshift for the sample is 1.6. Our result for this subsample suggest that our total sample of 150 sources may contain ~ 40 galaxies with Z > 2. We have imaged four of our galaxies having Z > 2 in the light of Lyα. Three of these have highly extended Lyα emission distributed along their radio axes.