First ASCA results for high-redshift Radio-Quiet Quasars

Abstract

Here we report the X-ray spectral analysis of 5 high-redshift ($z \geq 2$) radio-quiet quasars (RQQs) observed with the ASCA satellite. A simple power law with Galactic absorption model well fits the data. There is no evidence of a reflection component. The average spectral slope in the observed 0.5--10 keV energy range, $< Γ> = 1.68\pm{0.09}$ (dispersion $σ\sim 0.11$), places the high-z objects of the present sample in the lower-Γtail of the RQQs spectral indices distribution.

4 pages, 3 figures, Latex macros memsait.sty, epsfig.sty, epsf.tex, to be pubblished in the proceedings of the conference "Dal nano- al Tera-eV: tutti i colori degli AGN", third Italian conference on AGNs, Roma, 18-21 May 1998, Memorie S.A.It