Cobe, Inflation, and Light Scalars

Comparison of the COBE observed quadrupole anisotropy with that predicted in adiabatic CDM models suggests that much of the observed signal may be due to long wavelength gravitational waves. In inflationary models this requires the generation of tensor fluctuations to be at least comparable to scalar density fluctuations. This is feasible, but depends sensitively on the inflaton potential. Alternatively, isocurvature quantum fluctuations in an axion-like field could produce a quadrupole anisotropy proportional to the gravitational wave anisotropy, independent of the inflaton potential. These could also produce large scale structure with more power on larger scales than their adiabatic counterparts. Bitnet: Krauss@Yalehep. Research supported in part by the NSF,DOE, and TNRLC