J.N. Reeves (1), M.J.L. Turner (1), P.J. Bennie (1), K.A. Pounds (1), A. Short (1), P.T. O'Brien (1), Th. Boller (2), M. Kuster (3), and A. Tiengo (4)
(1) XRay Astronomy Group; Department of Physics and Astronomy; Leicester University; Leicester LE1 7RH; U.K.
(2) MaxPlanckInstitut für extraterrestrische Physik, Postfach 1603, 85748 Garching, Germany
(3) Institut für Astronomie und Astrophysik, Astronomie, Universität
Tübingen, Waldhäuser Str. 64, D-72076 Tübingen, Germany
(4) IFC Milan, 20133 Milano, Italy
2001, Astronomy & Astrophysics 365, L116 - L121
Abstract. 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-to-noise spectrum of a high-z quasar to date. The EPIC observations show that PKS 0537-286 is extremely X-ray luminous (Lx=2x1047 erg/s), with an unusually hard X-ray spectrum (Gamma=1.27+/-0.02). The flat power-law emission extends over the whole observed energy range; there is no evidence of intrinsic absorption, which has been claimed in PKS 0537-286 and other high z quasars. However, there is evidence for weak Compton reflection. A redshifted iron K line, observed at 1.5 keV - corresponding to 6.15 keV in the quasar rest frame - is detected at 95% confidence. If confirmed, this is the most distant iron K line known. The line equivalent width is small (33eV), consistent with the `X-ray Baldwin effect' observed in other luminous quasars. The reflected continuum is also weak (R=0.25). We find the overall spectral energy distribution of PKS 0537-286 is dominated by the X-ray emission, which, together with the flat power-law and weak reflection features, suggests that the X-radiation from PKS 0537-286 is dominated by inverse Compton emission associated with a face-on relativistic jet.Key words: galaxies: active - quasars: individual: PKS 0537-286 - X-rays: galaxies
Paper (77k gzip'ed Postscript including figures)
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