Issue |
A&A
Volume 446, Number 2, February I 2006
|
|
---|---|---|
Page(s) | 439 - 446 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361:20041963 | |
Published online | 13 January 2006 |
Long observations of the BALQSO LBQS 2212-1759 with XMM-Newton
1
Research & Scientific Support Department, ESTEC, SCI-SA, Postbus 299 2200 AG – Noordwijk, The Netherlands e-mail: Jean.Clavel@esa.int
2
XMM-Newton Science Operations Centre, ESAC, Apartado 50727, 28080 Madrid, Spain e-mail: [nscharte;ltomas]@xmm.vilspa.esa.es
Received:
6
September
2004
Accepted:
9
September
2005
Very long (172 ks effective exposure time) observations of the
BALQSO LBQS 2212-1759 with XMM-Newton yield a
stringent upper-limit on its 0.2–10 keV (rest- frame 0.64–32.2 keV) flux,
, while
simultaneous UV and optical observations reveal a rather blue spectrum
extending to 650 Åin the source rest frame. These results are
used to set a tight upper-limit on its optical to X-ray spectral index
. Given the HI-BAL nature of
LBQS 212-1759, its X-ray weakness is most likely due to
intrinsic absorption. If this is the case, and assuming that the intrinsic
of LBQS 2212-1759 is -1.63 – a value
appropriate for a radio-quiet quasar of this luminosity – one can set
a lower limit on the X-ray absorbing column
. Such a large column has a Thomson
optical depth to electron scattering
, sufficient
to extinguish the optical and UV emission. The contradiction becomes even
more acute if
the gas is neutral since the opacity in the Lyman continuum becomes
extremely large,
, conflicting with
the source detection below 912 Å. This apparent contradiction
probably means that our lines-of-sight to the X-ray and to the UV emitting
regions are different, such that the gas completely covers the
compact X-ray source but only partially the more extended source of
ultraviolet photons. An extended (
) X-ray source is
detected
to the south-east of the QSO. Given its thermal
spectrum and temperature (
), it is
probably a foreground (
) cluster of galaxies.
Key words: quasars: absorption lines / quasars: individual: LBQS 2212-1759 / X-rays: individuals: LBQS 2212-1759 / galaxies: active / X-rays: galaxies / ultraviolet: galaxies / galaxies: active
© ESO, 2006
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.