Issue |
A&A
Volume 451, Number 3, June I 2006
|
|
---|---|---|
Page(s) | 859 - 864 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361:20053980 | |
Published online | 04 May 2006 |
An X-ray bright ERO hosting a type 2 QSO
1
INAF – Osservatorio Astronomico di Brera (OAB), via Brera 28, 20121 Milano, Italy e-mail: [paola;caccia;braito;rdc;tommaso;saracco]@brera.mi.astro.it
2
Exploration of the Universe Division, NASA Goddard Space Flight Center, Greenbelt Road, Greenbelt, MD 20771, USA e-mail: vale@milkyway.gsfc.nasa.gov
3
Subaru Telescope, National Astronomical Observatory of Japan, 650 North A'ohoku Place, Hilo, HI 96720, USA e-mail: akiyama@subaru.naoj.org
4
Instituto de Fisica de Cantabria (CSIC-UC), Avenida de los Castros, 39005 Santander, Spain e-mail: [carreraf;ceballos]@ifca.unican.es
5
Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, Surrey RH5 6NT, UK e-mail: mjp@mssl.ucl.ac.uk
6
X-ray Astronomy Group, Department of Physics and Astronomy, Leicester University, Leicester LE1 7RH, UK e-mail: mgw@star.le.ac.uk
Received:
29
July
2005
Accepted:
4
February
2006
We present the XMM-Newton and the optical-VLT spectra along with
the optical and the near-infrared photometric data of one of the brightest
X-ray ( erg s-1 cm-2) extremely red
objects (
) discovered so far. The source, XBS J0216-0435, belongs to
the XMM-Newton Bright Serendipitous Survey and it has extreme
X-ray-to-optical (~220) and X-ray-to-near-infrared (~60) flux
ratios. Thanks to its brightness, the X-ray statistics are good enough for an
accurate spectral analysis by which the presence of an X-ray obscured
(
cm-2) QSO (
erg s-1) is determined. A statistically significant (~99%) excess
around 2 keV in the observed-frame suggests the presence of an emission line.
By assuming that this feature corresponds to the iron Kα line at 6.4 keV, a first estimate of the redshift of the source is
derived (
). The presence of a high redshift QSO2 has been finally confirmed
through dedicated VLT optical spectroscopic observations
(
). This result yields to an optical validation of a new
X-ray Line Emitting Object (XLEO) for which the redshift has
been firstly derived from the X-ray data. XBS J0216-0435 can be
considered one of the few examples of X-ray obscured QSO2 at high redshift
for which a detailed X-ray and optical spectral analysis has been possible.
The spectral energy distribution from radio to X-rays is also presented.
Finally from the near-infrared data the luminosity and the stellar mass of the
host galaxy has been estimated finding a new example of the coexistence at
high-z between massive galaxies and powerful QSOs.
Key words: galaxies: active / X-rays: galaxies / galaxies: individual: XBS J0216-0435
© ESO, 2006
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