XMM-Newton observations of the two X-ray weak quasars PG 1411+442 and Mrk 304

¹ Centre for Interdisciplinary Plasma Science, Max–Planck–Institut für extraterrestrische Physik, Postfach 1312, 85741 Garching, Germany
² Physics Department, University of Crete, 71 003 Heraklion, Crete, Greece
³ IESL, FORTH-Hellas, 71 110, Heraklion, Crete, Greece
⁴ Max–Planck–Institut für extraterrestrische Physik, Postfach 1312, 85741 Garching, Germany

Corresponding author: W. Brinkmann, wpb@mpe.mpg.de

Received: 29 July 2003
Accepted: 14 October 2003

Abstract

We present the results of XMM-Newton observations of two X-ray weak quasars, PG 1411+442  and Mrk 304 . In both cases the spectra can basically be represented by hard power laws with photon indices typical for radio-quiet quasars, heavily intrinsically absorbed by column densities of ~ cm^-2 in PG 1411+442 and ~ cm^-2 in Mrk 304. The data require in both cases an additional steep () soft power law component, absorbed only by the galactic column density towards the quasars. The soft parts of the spectra exhibit additional complex structures like emission line features around ~0.59 keV, and absorption edges around 0.7 keV and ~1 keV. These features strongly suggest the presence of “warm" (i.e. ionized) material in the central region of the two sources. Due to the insufficient photon statistics and to the lack of more advanced models for the spectral fitting, we are unable to determine accurately the geometry and physical state of the absorbing material. The physical implications of various viable spectral absorption or scattering scenarios for the nature of these objects and of the X-ray weak quasars in general, are discussed.