EDP Sciences
Free access
Volume 402, Number 2, May I 2003
Page(s) 465 - 476
Section Galactic structure and dynamics
DOI http://dx.doi.org/10.1051/0004-6361:20030275

A&A 402, 465-476 (2003)
DOI: 10.1051/0004-6361:20030275

XMM-Newton observations of four high-z quasars

E. Ferrero1 and W. Brinkmann2

1  Max-Planck-Institut für extraterrestrische Physik, Postfach 1312, 85741 Garching, Germany
2  Centre for Interdisciplinary Plasma Science, Max-Planck-Institut für extraterrestrische Physik, Postfach 1312, 85741 Garching, Germany

(Received 7 November 2002 / Accepted 18 February 2003)

We present the results of XMM-Newton observations of four high- z quasars, two radio-loud and two radio-quiet. One of the radio-loud objects, PKS 2126-158, clearly shows absorption in excess of the galactic value as claimed before from ASCA and ROSAT observations. For PKS 2149-306 the evidence for excess absorption is only marginal in contrast to previous results. The location of the absorber in PKS 2126-158 is compatible with the redshift of the source. Both, a warm and a cold absorber are allowed by the X-ray data. Both quasars have very flat photon spectra ( $\Gamma \la 1.5$) and the high photon statistics reveal small deviations from a simple power law form. For the two radio-quiet objects, Q 0000-263 and Q 1442+2931, we determine, for the first time, reliable spectral parameters. Both quasars have steeper power laws ( $\Gamma \sim 2$) and show absorption consistent with the galactic value, similar to radio-quiet quasars at low redshifts. In the case of Q 0000-263 the presence of the damped Ly $\alpha $ system ( $N({\rm HI})\sim 2.6\times 10^{21}$ cm -2 at z = 3.39) cannot be examined further due to the limited photon statistics in all instruments.

Key words: galaxies: active -- quasars: general -- X-rays: galaxies

Offprint request: E. Ferrero, ferrero@mpe.mpg.de

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© ESO 2003