Abstrakt
Dissipative features of dark matter affect its clustering properties and could lead to observable consequences for the evolution of large-scale structure. We analyse the evolution of cold dark matter density perturbations allowing for the possibility of bulk viscous pressure in a causal dissipative theory.
Our analysis employs a Newtonian approximation for cosmological dynamics and the transport properties of bulk viscosity are described by the Israel-Stewart theory. We obtain a third order evolution equation for density perturbations.
For some parameter values the density contrast can be suppressed compared to results obtained in the ΛCDM scenario. For other values causal bulk viscous dark matter can exhibit an enhancement of clustering.