LAUSR

In a spatially flat Friedmann-Lemaitre-Robertson-Walker universe, we investigate a unified cosmic fluid scenario endowed with bulk viscosity in which the coefficient of the bulk viscosity has a power law evolution. The power law in the bulk viscous coefficient is a general case in this study which naturally includes several choices as special cases. Considering such a general bulk viscous scenario, in the present work, we have extracted the observational constraints using the latest cosmological datasets and examine their behavior at the level of both background and perturbations. From the observational analyses, we find that a nonzero bulk viscous coefficient is always favored and some of the models in this series are able to weaken the current tension on H0 for some dataset. However, from the Bayesian evidence analysis, Λ cold dark matter is favored over the bulk viscous model.