Constraining Warm Inflation with the Cosmic Microwave Background

We discuss the spectrum of scalar density perturbations from warm inflation when the friction coefficient $\mathrm{\Gamma }$ 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 $\mathrm{\Gamma }$. 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.