The soft X-ray properties of a complete sample of radio sources

Abstract

We present the soft X-ray (0.1--2.4 keV) properties of a complete sample of\n88 southern radio sources derived from the Wall \\& Peacock 2-Jy sample. It\ncomprises 68 radio galaxies, 18 quasars and 2 BL Lac objects. Whereas both BL\nLac objects and all but one quasar are detected in the {\\it ROSAT} All-Sky\nSurvey, the fraction of detected radio galaxies is only $\\sim$ 60 per cent. For\nthe undetected sources upper limits to the X-ray flux are given. We confirm the\ncorrelation of the soft X-ray luminosity (\\lx) with the core radio luminosity\n(\\lc) for galaxies as well as for quasars using partial correlation analysis,\nwhereas the corresponding correlations between \\lx and \\lt are probably\nspurious due to sample selection effects. We also find strong correlations\nbetween \\lx and \\lc for both Fanaroff-Riley type I (FR~I) and type II galaxies.\nThe broad-line radio galaxies (BLRGs) and the quasars are at the top end of the\nX-ray luminosity distribution and the detection rate of these objects generally\nis higher than that of the narrow- or weak-lined radio galaxies. This indicates\nthe presence of an anisotropic X-ray component in BLRGs and quasars, as\npredicted by unified schemes for radio sources.\n