The X-ray reflectors in the nucleus of the Seyfert galaxy NGC 1068

Based on observations of the Seyfert nucleus in NGC 1068 with ASCA, RXTE, and BeppoSAX, we report the discovery of a are (increase in flux by a factor of similar to1.6) in the 6.7 keV Fe K line component between observations obtained 4 months apart, with no significant change in the other (6.21, 6.4, and 6.97 keV) Fe Kalpha line components. During this time, the continuum flux decreased by similar to20%. The RXTE spectrum requires an Fe K absorption edge near 8.6 keV (Fe XXIII-XXV). The spectral data indicate that the 2-10 keV continuum emission is dominated (similar to2/3 of the luminosity) by reflection from a previously unidentified region of warm, ionized gas located less than or similar to0.2 pc from the AGN. The remaining similar to1/3 of the observed X-ray emission is reflected from optically thick, neutral gas. The coronal gas in the inner narrow-line region and/or the cold gas at the inner surface of the obscuring "torus" are possible cold reflectors. The inferred properties of the warm reflector are size (diameter) less than or similar to0.2 pc, gas density ngreater than or similar to10(5.5) cm(-3), ionization parameter xiapproximate to10(3.5) ergs cm s(-1), and covering fraction 0.003(L-0/10(43.5) ergs s(-1))(-1) <(Ω/4π)<0.024(L-0/10(43.5) ergs s(-1))(-1), where L-0 is the intrinsic 2-10 keV X-ray luminosity of the AGN. We suggest that the warm reflector gas is the source of the ( variable) 6.7 keV Fe line emission and the 6.97 keV Fe line emission. The 6.7 keV line are is assumed to be due to an increase in the emissivity of the warm reflector gas from a decrease (by 20%-30%) in L-0. The properties of the warm reflector are most consistent with an intrinsically X-ray weak AGN with L(0)approximate to10(43.0) ergs s(-1). The optical and UV emission that scatters from the warm reflector into our line of sight is required to suffer strong extinction, which can be reconciled if the line of sight skims the outer surface of the torus. Thermal brems-strahlung radio emission from the warm reflector may be detectable in Very Long Baseline Array radio maps of the NGC 1068 nucleus.