  Structure formation creates high temperature and density regions in the
Universe that allow the conversion of matter into more stable states, with a
corresponding emission of relativistic matter and radiation. An example of such
a mechanism is the supernova event, that releases relativistic neutrinos
corresponding to 99% of the binding energy of remnant neutron star. We take
this phenomena as a starting point for an assumption that similar processes
could occur in the dark sector, where structure formation would generate a late
time conversion of cold dark matter into a relativistic form of dark matter. We
performed a phenomenological study about the limits of this conversion, where
we assumed a transition profile that is a generalized version of the neutrino
production in supernovae events. With this assumption, we obtained an
interesting modification for the constraint over the cold dark matter density.
We show that when comparing with the standard \Lambda CDM cosmology, there is
no preference for conversion, although the best fit is within 1\sigma\ from the
standard model best fit. The methodology and the results obtained qualify this
conversion hypothesis, from the large scale structure point of view, as a
viable and interesting model to be tested in the future with small scale data,
and mitigate discrepancies between observations at this scale and the pure cold
dark matter model.
