EDP Sciences
Free Access
Volume 403, Number 3, June I 2003
Page(s) 869 - 876
Section Galactic structure and dynamics
DOI https://doi.org/10.1051/0004-6361:20030395
Published online 23 May 2003

A&A 403, 869-876 (2003)
DOI: 10.1051/0004-6361:20030395

On the XMM-Newton spectra of soft X-ray selected QSOs

A. Akylas1, 2, I. Georgantopoulos1 and X. Barcons3

1  Institute of Astronomy & Astrophysics, National Observatory of Athens, Palaia Penteli, 15236 Athens, Greece
2  Physics Department, University of Athens, Panepistimiopolis, Zografos, 15783 Athens, Greece
3  Instituto de Fisica de Cantabria, CSIC-UC, 39905 Santander, Spain

(Received 31 May 2002 / Accepted 11 March 2003 )

We study the XMM-Newton spectra of a sample of 32 soft X-ray selected QSOs. Our goal is to check, using the spectra of moderate redshift ( $z\sim1.5$), faint ( $f_{0.2-8~{\rm keV}}>5\times 10^{-15}$  $\rm erg~cm^{-2}~s^{-1}$) broad-line QSOs, previous claims for either significant intrinsic absorption or spectral hardening at high energies. We derive hardness ratios for all sources and furthermore we perform spectral fits for the 11 brighter sources. The majority of sources have steep spectra $\Gamma>1.9$. We find a few QSOs with large amounts of intrinsic absorption, as high as $N_{\rm H}\sim10^{23}$  $\rm cm^{-2}$. We find no strong evidence for spectral hardening above 2 keV. The coadded QSO spectrum is well described by a single power-law with photon index of ~ 1.9, demonstrating that, on average, any effects of absorption are not important. This suggests that the discrepancy between the X-ray background and the (soft X-ray selected) QSO spectrum holds well at the faint fluxes probed here.

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

Offprint request: I. Georgantopoulos, ig@astro.noa.gr

SIMBAD Objects

© ESO 2003

Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.

Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.

Initial download of the metrics may take a while.