  Scalar and tensorial cosmological perturbations generated in warm
inflationary scenarios whose matter-radiation fluid is endowed with a viscous
pressure are considered. Recent observational data from the WMAP experiment are
employed to restrict the parameters of the model. Although the effect of this
pressure on the matter power spectrum is of the order of a few percent, it may
be detected in future experiments.

Astrophysics;General Relativity and Quantum Cosmology;High Energy Physics - Phenomenology