Radio-loud galaxies in the ROSAT survey. IV.

These sources have been selected from a cross-correlation of an early ROSAT All-Sky Survey source list with a list of compact radio sources of the 5GHz Green Bank northern sky survey (RGB sample, Cat. <VIII/52>). The majority of sources were quasi-simultaneously observed with the Effelsberg 100-m telescope at 11cm, 6cm, and 2.8cm.

We have determined the spectrum, size and linear polarization properties of these sources. We compare the radio data with ROSAT measurements and optical data. We find that the X-ray selected radio sources, when compared with unbiased radio source samples, are on average slightly more compact, show a higher fractional polarization, a higher absolute rotation measure (RM), and have flatter spectra.