THE REFLECTION-DOMINATED X-RAY-SPECTRUM OF NGC-6552

A serendipitous observation of the Seyfert 2 galaxy NGC 6552 by the ASCA Gas Imaging Spectrometer shows this object to have a remarkable X-ray spectrum. It displays a strong Ka line of neutral iron, in addition to low-energy structure. Here we present a model in which reflection from neutral matter dominates the X-ray spectrum. The model includes fluorescence of C, O, Ne, Mg, Si, S, Ar, Ca, Cr, Fe and Ni. A good fit is obtained by assuming that the reflector is of cosmic abundance in these elements; the data require that the iron abundance be within a factor of 2 of the cosmic value. The reflector orientation and the possibility of constraining abundances further are discussed. The implication of such reflection-dominated sources for the X-ray background is also discussed.