Bibcode
Akylas, A.; Georgantopoulos, I.; Georgakakis, A.; Kitsionas, S.; Hatziminaoglou, E.
Referencia bibliográfica
Astronomy and Astrophysics, Volume 459, Issue 3, December I 2006, pp.693-701
Fecha de publicación:
12
2006
Revista
Número de citas
97
Número de citas referidas
92
Descripción
We combine bright XMM-Newton data with the Chandra Deep Field South
observations to explore the behavior of the intrinsic AGN absorption, as
a function of redshift and luminosity. Our sample consists of 359
sources selected in the hard 2-8 keV band, spanning the flux range 6
× 10-16-3 × 10-13
erg~cm-2~s-1 with a high rate of spectroscopic or
photometric redshift completeness (100 and 85 per cent respectively for
the Chandra and XMM-Newton data). We derive the column density values
using X-ray spectral fits. We find that the fraction of obscured AGN
falls with increasing luminosity in agreement with previous findings.
The fraction of obscured AGN shows an apparent increase at high
redshifts (z>2). Simulations show that this effect can most probably
be attributed to the fact that at high redshifts the column densities
are overestimated.