2004MNRAS.355..330G

The XMM-Newton observation of the narrow-line quasar NAB 0205+024 reveals three striking differences since it was last observed in X-rays with ASCA. First, the 2-10 keV power law is notably steeper. Secondly, a hard X-ray flare is detected, very similar to that seen in I Zw 1. Thirdly, a strong and broad emission feature is detected with the bulk of its emission redward of 6.4 keV, and extending down to ∼5 keV in the rest frame. The most likely explanation for the broad feature is neutral iron emission emitted from a narrow annulus of an accretion disc close to the black hole. The hard X-ray flare could be the mechanism that illuminates this region of the disc, allowing for the emission line to be detected. The combination of effects can be understood in terms of the `thunder-cloud' model proposed by Merloni & Fabian.