The blazar PKS 0528+134: new results from BeppoSAX observations

BeppoSAX observed 8 times the -ray bright blazar PKS 0528+134 in Feb. and Mar. 1997, during a multiwavelength campaign involving EGRET, onboard CGRO, and ground based telescopes. The source was in its faintest X-ray state ob- served so far, with an unabsorbed (2-10) keV flux of 2:5 10 12 erg cm 2 s 1 . The spectrum can be fitted with a power law, with energy index X =0 :49 0:07 between 0.1 and 10 keV. The high energy instrument PDS detected a flux in the 15-100 keV band which appears disconnected from the lower X-ray energies, most likely due to a contaminating source. We consider our findings in the context of the overall spectral en- ergy distribution and discuss their implications for synchrotron and inverse Compton models.