Issue |
A&A
Volume 432, Number 1, March II 2005
|
|
---|---|---|
Page(s) | 15 - 30 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361:20041621 | |
Published online | 22 February 2005 |
The XMM-Newton view of PG quasars*
I. X-ray continuum and absorption
XMM-Newton Science Operation Center (ESAC), Apartado 50727, 28080 Madrid, Spain e-mail: epiconce@xmm.vilspa.esa.es
Received:
8
July
2004
Accepted:
26
October
2004
We present results of a systematic analysis of the XMM-Newton spectra of 40 quasars (QSOs) () from the Palomar-Green (PG) Bright
Quasar Survey sample (
23). The sample includes 35 radio-quiet
quasars (RQQs) and 5 radio-loud quasars (RLQs). The analysis of the
spectra above 2 keV reveals that the hard X-ray continuum emission
can be modeled with a power law component with
and
for
the RQQs and RLQs, respectively. Below 2 keV, a strong, broad
excess is present in most QSO spectra. This feature has been fitted
with four different models assuming several physical scenarios.
All tested models (blackbody, multicolor blackbody,
bremsstrahlung and power law) satisfactorily fitted the majority of
the spectra. However, none of them is able to provide an adequate
parameterization for the soft excess emission in all QSOs,
indicating the absence of a universal shape for this spectral
feature.
An additional cold absorption component was required only in three
sources. On the other hand, as recently pointed out by Porquet et al. ([CITE]) for a smaller sample of PG QSOs,
warm absorber features are present in 50% of the QSO spectra in contrast with their rare occurrence
(~5-10%) in previous studies. The XMM-Newton view of
optically selected bright QSOs therefore suggests that there are
no significant differences in the X-ray spectral properties
compared with those of the low-luminosity Seyfert 1 galaxies.
Properties of the Fe Kα emission lines are presented in a
companion paper.
Key words: galaxies: active / galaxies: nuclei / galaxies quasars: general / X-rays: galaxies
© ESO, 2005
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