COSMIC MICROWAVE BACKGROUND ANISOTROPIES IN COLD DARK-MATTER MODELS WITH COSMOLOGICAL CONSTANT - THE INTERMEDIATE VERSUS LARGE ANGULAR SCALES

We obtain predictions for cosmic microwave background anisotropies at angular scales near 1-degrees in the context of cold dark matter models with a nonzero cosmological constant, normalized to the COBE-DMR detection. The results are compared to those computed in the matter-dominated models. We show that the coherence length of the CMB anisotropy is almost insensitive to cosmological parameters, and the rms amplitude of the anisotropy increases moderately with decreasing total matter density, while being most sensitive to the baryon abundance. We apply these results in the statistical analysis of the published data from the UCSB South Pole (SP) experiment (Gaier et al. 1992; Schuster et al. 1993). We reject most of the CDM-LAMBDA models at the 95% confidence level when both SP scans are simulated together (although the combined data set renders less stringent limits than the Gaier et al. data alone). However, the Schuster et al. data considered alone, as well as the results of some other recent experiments (MAX, MSAM, Saskatoon), suggest that typical temperature fluctuations on degree scales may be larger than is indicated by the Gaier et al. scan. If so, CDM-LAMBDA models may indeed provide, from the point of view of CMB anisotropies, an acceptable alternative to flat CDM models.