  XMM-Newton RGS spectra of MCG-6-30-15 and Mrk 766 exhibit complex discrete
structure, which was interpreted in a paper by Branduardi-Raymont et al. (2001)
as evidence for the existence of relativistically broadened Lyman alpha
emission from carbon, nitrogen, and oxygen, produced in the inner-most regions
of an accretion disk around a Kerr black hole. This suggestion was subsequently
criticized in a paper by Lee et al. (2001), who argued that for MCG-6-30-15,
the Chandra HETG spectrum, which is partially overlapping the RGS in spectral
coverage, is adequately fit by a dusty warm absorber model, with no
relativistic line emission. We present a reanalysis of the original RGS data
sets in terms of the Lee et al. (2001) model, and demonstrate that spectral
models consisting of a smooth continuum with ionized and dust absorption alone
cannot reproduce the RGS spectra of both objects. The original relativistic
line model with warm absorption proposed by Branduardi-Raymont et al. (2001)
provides a superior fit to the RGS data, both in the overall shape of the
spectrum and in the discrete absorption lines. Limits on the amount of X-ray
absorption by dust particles are discussed. We also discuss a possible
theoretical interpretation for the putative relativistic Lyman alpha line
emission in terms of the photoionized surface layers of the inner regions of an
accretion disk.
