  Observed rotational curves of neutral hydrogen clouds strongly support the
fact that galactic halo contains huge amount of nonluminous matter, the so
called gravitational dark matter. The nature of dark matter is a point of
debate among the researchers. Recent observations reported the presence of ions
of O, S, C, Si etc in the galactic halo and intergalactic medium. This supports
the possibility of existence of electric field in the galactic halo region. We
therefore propose a model of galactic halo considering this electric field
arising due to charged particles as one of the inputs for the background
spacetime metric. Considering dark matter as an anisotropic fluid we obtain the
expressions for energy density and pressure of dark matter there and
consequently the equation of state of dark matter. Various other aspects of the
solutions are also analyzed along with a critical comparison with and
constraints of different observational evidences.
