  The Keplerian distribution of velocities is not observed in the rotation of
large scale structures, such as found in the rotation of spiral galaxies. The
deviation from Keplerian distribution provides compelling evidence of the
presence of non-luminous matter i.e. called dark matter. There are several
astrophysical motivations for investigating the dark matter in and around the
galaxy as halo. In this work we address various theoretical and experimental
indications pointing towards the existence of this unknown form of matter.
Amongst its constituents neutrino is one of the most prospective candidates. We
know the neutrinos oscillate and have tiny masses, but there are also
signatures for existence of heavy and light sterile neutrinos and possibility
of their mixing. Altogether, the role of neutrinos is of great interests in
cosmology and understanding dark matter.
