Microwave background anisotropies and large scale structure constraints onisocurvature modes in a two-field model of inflation

In this paper we study the isocurvature mode contribution to the cosmic mic rowave background anisotropies and the large scale structure power spectrum , for a two-field model of inflation proposed by Linde and Mukhanov. We pro vide constraints on the parameters of the model by comparing its prediction s with observations of the microwave background anisotropies, large scale s tructure data on the galaxy power spectrum, and the number density of nearb y galaxy clusters. We find that such models are consistent with observation s for a narrow range of parameters. As our main result, we find that only a very small isocurvature component is allowed, alpha less than or equal to 0.006, for any underlying Friedmann model. Furthermore, we give the expecte d resolution with which the model parameters will be determined from future satellite missions like MAP and Planck, for a fiducial at Lambda CDM model . We find that Planck mission will be able to detect such small contributio ns, especially if polarization information is included. The isocurvature sp ectral index n(iso) will also be determined with better than 8% precision.