ASCA Observation of Unusually X-Ray-Hard Radio-Quiet QSO Kaz102

Abstract

Abstract We observed the radio-quiet QSO Kaz102 $(z = 0.136)$ with ASCA as a part of our program for a complete spectral characterization of hard X-ray selected AGNs. We found that Kaz102 shows unusual spectral properties. A simple power-law with absorption in our Galaxy gave a satisfactory description of the spectrum. However, it showed a very hard photon index of $\Gamma \sim 1.0$ with no sign of deep absorption or a prominent spectral feature. We further explored the Compton reflection with the Fe $\mathrm{K}\alpha$ line and warm absorber models for hardening the spectra. Both gave statistically satisfactory fits. However, the Compton reflection model requires a very low metal abundance (0.03–0.07 in solar units). The warm absorber model with no direct component is preferred, and gave a very high ionization parameter of $\xi \sim 10^{2.3}$. If this is the case, the values of $\xi$, warm absorber column density, and variability over $\sim 10\;\mathrm{yr}$ may suggest that the warm absorber resides in the broad-line region and crosses the line of sight to the central X-ray source.