Cosmic microwave background anisotropies: Has a gravitational wave background been observed?

We show that in the scale-free chaotic inflationary scenario with the inflaton potential $\frac{\lambda {\phi }^4}{4}$, large-scale angular fluctuations in the cosmic microwave background radiation temperature generated by adiabatic density perturbations and gravitational waves are generically of the same order of magnitude and their ratio is parameter independent. In the inflationary models based on grand unified theories, these quantities can depend on different parameters and thus may differ by a large amount. The recent Cosmic Background Explorer observations have the potential to discover a cosmological background of gravitational waves and provide support for chaotic inflation or some other inflationary scenario giving a large gravitational wave background.