Exploring the Self Interacting Dark Matter Properties From Low Redshift
  Observations
  The small scale observations indicate that the dark matter may be
self-interacting. In this paper, we calculate the shear ($\eta$) and bulk
viscosity ($\zeta$) of Self Interacting Dark Matter (SIDM) fluid, in kinetic
theory formalism. Further, using the KSS bound on $\eta/\mathfrak{s}$, we
derive a new upper limit on the ratio of dark matter self interaction cross
section to its mass, $ \sigma/m $. Then, using the $ \sigma/m $ constraint, we
show that KSS bound allows only sub-GeV mass of SIDM particle. Further, with
the assumption of a power-law form of $\eta$ and $\zeta$, we study its
evolution in the light of low redshift observations. We find that at the large
redshift, the SIDM viscosity is small but at the small redshift it becomes
sufficiently large and contributes significantly in cosmic dissipation. As a
consequence, viscous SIDM can explain the low redshift observations and also
consistent with the standard cosmological prediction.
