  We present new, high signal-to-noise ratio results from a Monte Carlo study
of the properties of the Compton shoulder of the Fe Kalpha emission line in the
toroidal X-ray reprocessor model of Murphy & Yaqoob (2009, MNRAS, 397, 1549).
The model comprehensively covers the Compton-thin to Compton-thick regimes and
we find that the variety of Compton shoulder profiles is greater than that for
both (centrally-illuminated) spherical and disk geometries. Our Monte Carlo
simulations were done with a statistical accuracy that is high enough to
reveal, for the case of an edge-on, Compton-thick torus, a new type of Compton
shoulder that is not present in the spherical or disk geometries. Such a
Compton shoulder is dominated by a narrow back-scattering feature at ~6.24 keV.
Our results also reveal a dependence of the shape of the Compton shoulder (and
its magnitude relative to the Fe Kalpha line core) on the spectral shape of the
incident X-ray continuum. We also show the effects of velocity broadening on
the Fe Kalpha line profile and find that if either the velocity width or
instrument resolution is greater than a FWHM of ~2000 km/s, the Compton
shoulder begins to become blended with the line core and the characteristic
features of the Compton shoulder become harder to resolve. In particular, at a
FWHM of ~7000 km/s the Compton shoulder is NOT resolved at all, its only
signature being a weak asymmetry in the blended line profile. Thus, CCD X-ray
detectors cannot unambiguously resolve the Compton shoulder. Our results are
freely available in a format that is suitable for direct spectral-fitting of
the continuum and line model to real data.
