Powerful Radio Sources in the Southern Sky. II. A Swift X-Ray Perspective

Abstract

We recently constructed the G4Jy-3CRE, a catalog of extragalactic radio sources based on the GLEAM 4-Jy (G4Jy) sample, with the aim of increasing the number of powerful radio galaxies and quasars with similar selection criteria to those of the revised release of the Third Cambridge Catalog (3CR). The G4Jy-3CRE consists of a total of 264 radio sources mainly visible from the Southern Hemisphere. Here, we present an initial X-ray analysis of 89 G4Jy-3CRE radio sources with archival X-ray observations from the Neil Gehrels Swift Observatory. We reduced a total of 624 Swift observations, for about 0.9 Ms of integrated exposure time. We found X-ray counterparts for 59 radio sources belonging to the G4Jy-3CRE, nine of them showing extended X-ray emission. The remaining 30 sources do not show any X-ray emission associated with their radio cores. Our analysis demonstrates that X-ray snapshot observations, even if lacking uniform exposure times, as those carried out with Swift, allow us to (i) verify and/or refine the host galaxy identification; (ii) discover the extended X-ray emission around radio galaxies of the intracluster medium when harbored in galaxy clusters, as the case of G4Jy 1518 and G4Jy 1664; and (iii) detect X-ray radiation arising from their radio lobes, as for G4Jy 1863.

Powerful Radio Sources in the Southern Sky. III. First Results of the Optical Spectroscopic Campaign

“…In Massaro et al (2023b) (hereinafter Paper II) we presented X-ray archival data from the X-Ray Telescope on board the Neil Gherels Swift satellite for 89 G4Jy-3CRE sources. All these sources had at least one observation with exposure time longer than 250 s. The analysis of these X-ray observations allowed us to investigate the presence of diffuse/extended X-ray emission around G4Jy-3CRE sources, detect X-ray emission from radio lobes, and verify and/or refine the host galaxy identification.…”