The first XMM-Newton spectrum of a high redshift quasar - PKS 0537-286

We present XMM-Newton observations of the high redshift (z = 3.104), radio- loud quasar PKS 0537-286. The EPIC CCD cameras provide the highest signal-t o-noise spectrum of a higll-z quasar to date. The EPIC observations show th at PKS 0537-286 is extremely X-ray luminous (L-X = 2 10(47) erg s(-1)), wit h an unusually hard X-ray spectrum (Gamma = 1.27 +/- 0.02). The flat power- lam emission extends ol cr the whole observed energy range (0.4 to 40 keV i n the quasar rest frame); there is no evidence of intrinsic absorption, whi ch has been claimed in PKS 0537-286 and other high z quasars. However, ther e is evidence for weak Compton reflection. A red-shifted iron K line, obser ved at 1.5 keV - corresponding to similar to6.15 keV in the quasar rest fra me is detected at 95% confidence. If confirmed, this is the most distant ir on K line known. The line equivalent width is small (33 eV), consistent wit h the IX-ray Baldwin effect'' observed in other luminous quasars. The refle cted continuum X-ray emission, which: together with the flat power-law and weak reflection features, suggests that the X-radiation from PKS 0537-286 i s dominated by inverse Compton emission associated with a face-on relativis tic jet.