X-ray observations of low-power FR I radio galaxies

According to unified schemes for Active Galactic Nuclei, low-power, Fanaroff-Riley type I (FR I), radio galaxies are thought to be BL Lacs with their jets pointing at relatively large angles with respect to the line of sight. X-ray observations of FR I sources can test this scenario and constrain the presence of obscuring material around the nucleus. In this paper we discuss the X-ray properties of three FR I radio galaxies 3C 78, OH-342 and PKS 0620-52, observed with the BeppoSAX satellite in the 0.2-10 keV energy range. The narrow-field instruments on board BeppoSAX have detected extended thermal X-rap emission from a hot galactic corona (3C 78) and intracluster gas (OH-342 and PKS 0620-52). However, a detailed spectral analysis suggests that a non-thermal (likely nuclear) component can also significantly contribute to the total flux, especially in the case of 3C 78 and OH-342. This emission from the central region appears basically unabsorbed, in agreement with observations in other bands. The X-ray spectral luminosity of the nucleus of these three objects is correlated with the radio core luminosity, consistently with previous data on other FR I radio galaxies.