3. The Iron Line

The iron line has a finite physical width which is consistent with its identification as a blend of lines from neutral and highly ionized iron. The absence of a deep absorption edge at 7.1 keV indicates that the line is caused mainly by reflection of the continuum by a fluorescing medium.

One disturbing fact is that the pulse-phase average iron line width depends on the continuum model. This effect is most evident in Figure 3.2 where the iron line has an unphysical width due to the poor modelling of the continuum by the cut-off power law model. Nevertheless, the pulse-phase dependence of the iron line intensity appears to be consistent between different continuum models.