Probing the hard X-ray properties of high-redshift Radio-Quiet Quasars with ASCA

C. Vignali; A. Comastri; M. Cappi; G. G. C. Palumbo; M. Matsuoka; H. Kubo

doi:10.1086/307141

paper

Probing the hard X-ray properties of high-redshift Radio-Quiet Quasars with ASCA

arXiv:astro-ph/9812176 · doi:10.1086/307141

Abstract

This paper reports the X-ray spectral analysis of 5 high-redshift (z \ge 2) radio-quiet quasars observed by ASCA. A simple power law continuum plus cold Galactic absorption model well fits all the spectra (tipically between $\sim$ 2-30 keV in the sources frame). Neither the X-ray spectral hardening, attributed to a reflection component and observed in Seyfert galaxies, nor the excess absorption previously detected in high-redshift radio-loud quasars, have been revealed. Only a marginal evidence of a neutral or mildly ionized FeKαline is found in one of the quasars. The average spectral slope in the observed 0.7--10 keV energy range, $< Γ >= 1.67 \pm 0.11$ (dispersion $σ \sim 0.07$ ), appears to be flatter than that of low-z radio-quiet quasars ( $Γ ≃ 1.9 - 2$ ) and slightly steeper, but consistent with $Γ$ = 1.61 \pm{0.04} (σ\sim 0.10)$ of high-z radio-loud quasars.

9 pages, emulateapj style, plus 16 figures. Accepted for publication in the Astrophysical Journal

Probing the hard X-ray properties of high-redshift Radio-Quiet Quasars with ASCA

Abstract

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