  We describe features that could be observed in the line spectra of relic
cosmological particles should quantum nonequilibrium be preserved in their
statistics. According to our arguments, these features would represent a
significant departure from those of a conventional origin. Among other
features, we find a possible spectral broadening that is proportional to the
energy resolution of the recording telescope (and so could be much larger than
any conventional broadening). Notably, for a range of possible initial
conditions we find the possibility of spectral line "narrowing", whereby a
telescope could observe a line that is narrower than it is conventionally able
to resolve. We discuss implications for the indirect search for dark matter,
with particular reference to some recent controversial spectral lines.
