Dynamics of Dark Matter in Baryon-Radiation Plasma: Perspectives using
  Meschersky equation
  With an aim to argue for the truly collisionless nature of cold dark matter
between epochs of equality and recombination, we assume a model, wherein
strongly coupled baryon-radiation plasma ejects out of small regions of
concentrated cold dark matter without losing its equilibrium. We use the
Meschersky equation to describe the dynamics of cold dark matter in the
presence of varying mass of strongly coupled baryon-radiation plasma. Based on
this model, we discuss the growth of perturbations in cold dark matter both in
the Jeans theory and in the expanding universe using Newton's theory. We see
the effect of the perturbations in the cold dark matter potential on the cosmic
microwave background anisotropy that originated at redshifts between equality
and recombination i.e. $1100 < z < z_{eq}$. Also we obtain an expression for
the Sachs-Wolfe effect, i.e. the CMB temperature anisotropy at decoupling in
terms of the perturbations in cold dark matter potential. We obtain similar
solutions both in the static and in the expanding universe, for epochs of
recombination. From this, we infer about the time scale when the dark energy
starts to dominate.
