Issue |
A&A
Volume 442, Number 3, November II 2005
|
|
---|---|---|
Page(s) | L53 - L56 | |
Section | Letters | |
DOI | https://doi.org/10.1051/0004-6361:200500189 | |
Published online | 14 October 2005 |
Letter to the Editor
XMM-Newton discovery of soft X-ray absorption in the high-z superluminous Blazar RBS 315
European Space Astronomy Center (ESA), Apartado 50727, 28080 Madrid, Spain e-mail: Enrico.Piconcelli@sciops.esa.int
Received:
18
May
2005
Accepted:
14
September
2005
We present the analysis and the results of a 20 ks
XMM-Newton observation of the extremely X-ray loud ( erg s-1) flat-spectrum radio quasar RBS 315 at a
redshift of 2.69. This EPIC observation has allowed us to strongly
constrain the slope of the continuum (
) as
well as to discover the presence of a sharp drop below ≈2 keV in its spectrum.
Such a flat photon index and the huge luminosity suggest that the
X-ray emission is due to the low energy tail of the Comptonized
spectrum, produced from plasma in a relativistic jet oriented close
to our line of sight. Even though the hypothesis of a break in the
continuum cannot be completely discarded as an explanation of the soft
X-ray cutoff, the presence of intrinsic absorption appears more plausible.
Spectral fits with cold (
=
1.62
1022 cm-2) and lukewarm (
= 2.2
1022 cm-2; ξ = 15
erg cm-2 s-1) absorbers are
statistically indistinguishable. Remarkably, our results are very similar to
those reported so far for other absorbed high-z Blazars observed by
XMM-Newton. The existence of this “homogeneous” class of jet-dominated
superluminous obscured QSOs at high z therefore could be
important in the context of the formation and cosmological evolution
of radio-loud objects.
Key words: galaxies: active / quasar: general / X-ray: individual: RBS 315
© ESO, 2005
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