Power Spectrum of Primordial Inhomogeneity Determined from the FOUR-Year [ITAL]COBE[/ITAL] DMR Sky Maps

Abstract

Fourier analysis and power spectrum estimation of the cosmic microwave background anisotropy on an incompletely sampled sky developed by Gorski has been applied to the 4 yr COBE DMR 31.5, 53, and 90 GHz sky maps. Likelihood analysis using newly constructed Galaxy cuts (extended beyond |b| = 20 deg to excise the known foreground emission) and simultaneously correcting for the faint high-latitude Galactic foreground emission is conducted on the DMR sky maps pixelized in both ecliptic and Galactic coordinates. The Bayesian power spectrum estimation from the foreground-corrected 4 yr COBE DMR data renders n ~ 1.2 +/- 0.3 and Qrms-PS ~ 15.3^{+3.7}_{-2.8} mu K (projections of the two-parameter likelihood). The results are consistent with the Harrison-Zeldovich n = 1 model of amplitude Qrms-PS ~ 18 mu K detected with significance exceeding 14 sigma ( delta Q/Q