Constraining warm inflation with the cosmic microwave background

We discuss the spectrum of scalar density perturbations from warm inflation when the friction coefficient Gamma in the inflaton equation is dependent on the inflaton field. The spectral index of scalar fluctuations depends on a new slow-roll parameter constructed from Gamma. A numerical integration of the perturbation equations is performed for a model of warm inflation and gives a good fit to the WMAP data for reasonable values of the model's parameters. (C) 2004 Published by Elsevier B.V.