2005A&A...442L..53P -
Astronomy and Astrophysics, volume 442, L53-56 (2005/11-2)
XMM-Newton discovery of soft X-ray absorption in the high-z superluminous Blazar RBS 315.
PICONCELLI E. and GUAINAZZI M.
Abstract (from CDS):
We present the analysis and the results of a 20ks XMM-Newton observation of the extremely X-ray loud (LX≃5x1047erg/s) 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 (Γ=1.23±0.01) as well as to discover the presence of a sharp drop below ≃2keV 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 (NHz=1.62+0.09–0.09x1022cm–2) and lukewarm (NHz=2.2+0.9–0.3x1022cm–2; ξ=15+38–12erg/cm2/s) 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.
Abstract Copyright:
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Journal keyword(s):
galaxies: active - quasar: general - X-ray: individual: RBS 315
Simbad objects:
3
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