Viscous Cold Dark Matter in agreement with observations
  We discuss bulk viscous cosmological models. Since the bulk viscous pressure
is negative, viable viscous cosmological scenarios with late time accelerated
expansion can in principle be constructed. After discussing some alternative
models based on bulk viscous effects we will focus on a model very similar to
the standard $\Lambda$CDM. We argue that a $\Lambda${\rm v}CDM model, where we
assign a very small (albeit perceptible) bulk viscosity to dark matter is in
agreement with available cosmological observations. Hence, we work with the
concept of viscous Cold Dark Matter ({\rm v}CDM). At the level of the
perturbations, the growth of {\rm v}CDM structures is slightly suppressed when
compared with the standard CDM ones. Having in mind that the small scale
problems of the $\Lambda$CDM model are related to an excess of clustering, our
proposal seems to indicate a possible direction for solving the serious
drawbacks of the CDM paradigm within the standard cosmological model.
