Signal-to-Noise Eigenmode Analysis of the Two-Year COBE Maps

To test best a theory of cosmic microwave background fluctuations, anisotropy maps [here the two-year Cosmic Background Explorer differential microwave radiometer (DMR) 53,90,31GHz a and b and the Far-Infrared Survey (FIRS) 170 GHz maps] are expanded in a complete basis of linear combinations of pixel amplitudes---statistically independent for both the noise and the signal. Bayesian analysis of a 2-parameter inflation-inspired theory shows the overall band-power and spectral tilt index ν_ΔT+1 for all maps agree within 1σ, (1.1±0.1)×10^-5² and 1.27±0.33 (compatible with inflation values, ~0.8-1.2); and $S/N$ filtering of the DMR maps reveals the same large-scale structural features.