STUDIES OF COSMIC MICROWAVE BACKGROUND STRUCTURE AT DEC=-DEGREES .2. ANALYSIS AND COSMOLOGICAL INTERPRETATION(40)

We present a detailed analysis of the cosmic microwave background (CMB ) structure in the Tenerife Dec. = + 40 degrees data. The effect of lo cal atmospheric contributions on the derived fluctuation amplitude is considered, resulting in an improved separation of the intrinsic CMB s ignal from noise. Our analysis demonstrates the existence of common st ructure in independent data scans at 15 and 33 GHz. For the case of fl uctuations described by a Gaussian autocorrelation function, a likelih ood analysis of our combined results at 15 and 33 GHz implies an intri nsic rms fluctuation level of 48(-15)(+21)mu K on a coherence scale of 4 degrees; the equivalent analysis for a Harrison-Zel'dovich model gi ves a power spectrum normalization of Q(rms-ps) = 22(-6)(+10) mu K. Th e fluctuation amplitude is seen to be consistent at the 68 per cent co nfidence level with that reported for the COBE two-year data for primo rdial fluctuations described by a power-law model with a spectral inde x in the range 1.0 less than or equal to n less than or equal to 1.6. This limit favours the large-scale CMB anisotropy being dominated by s calar fluctuations rather than tensor modes from a gravitational wave background. The large-scale Tenerife and COBE results are considered i n conjunction with observational results from medium-scale experiments in order to place improved limits on the fluctuation spectral index; we find n = 1.10 +/- 0.10 assuming standard CDM with H-0 = 50 km s(-1) Mpc(-1).