EDP Sciences
Free Access
Volume 414, Number 1, January IV 2004
Page(s) 107 - 116
Section Galactic structure and dynamics
DOI https://doi.org/10.1051/0004-6361:20031617

A&A 414, 107-116 (2004)
DOI: 10.1051/0004-6361:20031617

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

W. Brinkmann1, I. E. Papadakis2, 3 and E. Ferrero4

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

(Received 29 July 2003 / Accepted 14 October 2003)

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 ~ $2\times10^{23}$ cm -2 in PG 1411+442 and ~ $4\times10^{22}$ cm -2 in Mrk 304. The data require in both cases an additional steep ( $\Gamma \sim 3$) 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.

Key words: galaxies: active -- quasars: general -- quasars: individual: PG 1411+442, Mrk 304

Offprint request: W. Brinkmann, wpb@mpe.mpg.de

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