Seyfert 2 galaxies with unusually wide nebular lines
  We report on a set of AGN that match the Seyfert 2 galaxy classification
criteria, but display unusually wide "narrow" lines, with the 4959 {\AA} and
5007 {\AA} nebular lines overlapping with each other. This spectral line
broadening is in most cases evidence of a complex profile with multiple
components. It indicates an unusual narrow line region with diverse gas clouds
and a range of velocity systems. We list 14 such objects with these
characteristics identified in a set of Sloan Digital Sky Survey spectra. We
measure the strengths of all lines visible in the spectrum, and attempt to fit
multiple Gaussian profiles to the nebular lines. We quantify the line
parameters of all multiple velocity systems discovered. We compare the spectral
characteristics of our sample with those of other, 'conventional' type 2
Seyferts and attempt to determine whether other systematic spectral differences
exist. We consider whether the investigated sample constitutes a clear
sub-class of the Seyfert 2 population. In conclusion we offer possible
explanations for the unusual line profiles.
