The discovery of the microwave background anisotropy by the Cosmic Background Explorer (COBE) satellite is in accord with the inflationary scenario. For five promising models involving a single scalar field, the coupling constants and the fluctuation spectra are calculated including a correction for gravitational radiation. The primordial density fluctuation spectrum computed from these models is not exactly scale-invariant; the spectral index is constrained to be n≳0.8 for inflation with an exponential potential (assuming that the biasing parameter for galaxies ${\mathit{b}}_{\mathrm{\rho }}$<2). The implications for biased galaxy formation scenarios are discussed.

• Received 24 June 1992

DOI:https://doi.org/10.1103/PhysRevLett.69.3602