The relatively strong spectral features observed in this source make it an interesting case to use for an investigation of models for reprocessing of the X-ray continuum by ionized material. We consider ionized reprocessors based upon the XSTAR photoionization code, for geometries in and out of the line-of-sight. Models in either geometry provide a vast improvement over a simple absorbed power-law model.
The warm absorber/emitter model provides a good explanation of the overall spectral shape, with a column density of N_{H,z}^* approx 8x10^{21} cm^{-2} of ionized material (ionization parameter xi = 24) most likely within approx 10^{17} cm of the central source. While the data do not allow us to unambiguously determine the origin of the spectral variability, it is consistent with a drop of approx 25% in flux accompanied by a proportional drop in the ionization--state of the warm absorber. The intense K-alpha line of equivalent width approx 500 eV present in the source can be modeled as a gaussian of FWHM apprx 0.5 keV or by a line profile expected from the inner regions of a relativistic accretion disk inclined at approx 30 deg. In both cases the rest-frame line energy is consistent with weakly ionized iron, and cannot be explained by the warm emitter.
An ionized reflector can also model the overall spectral shape, yielding xi_{ref} approx 80, although it has some difficult simultaneously fitting both the iron K-alpha line and the soft X-ray spectral features. This model offers no simple explanation for the observed spectral variability, and the intensity of the reflected component is greater than that expected from a semi-infinite slab illuminated by an isotropic source.
A hybrid model featuring reprocessing in both the warm absorber/emitter and reflector may be the most realistic scenarion. In this case the preferred fit models the soft X-ray regime (and spectral variability) with the warm absorber/emitter, and the iron K-alpha line with a weakly ionized reflector (xi approx-less-than 20).