Imprints of Non-thermal Wino Dark Matter on Small-Scale Structure
  We study how "warm" the wino dark matter is when it is non-thermally produced
by the decays of the gravitino in the early Universe. We clarify the energy
distribution of the wino at the decay of the gravitino and the energy loss
process after their production. By solving the Boltzmann equation, we show that
a sizable fraction of the wino dark matter can be "warm" for the wino mass
m_{\tilde w} \sim 100-500 GeV. The "warmness" of the wino dark matter leaves
imprints on the matter power spectra and may provide further insights on the
origin of dark matter via the future 21 cm line survey. Our calculations can be
applied to other non-thermal wino production scenarios such as the wino dark
matter produced by the decay of the moduli fields.
