Monte Carlo Simulations of Medium-Scale Cosmic Microwave Background Anisotropy

Abstract

Recent detections of cosmic microwave background (CMB) anisotropy at half-degree angular scales show considerable scatter in the reported amplitude, even at similar angular resolution. We use Monte Carlo techniques to simulate the current set of medium-scale CMB observations, including all relevant aspects of sky coverage and measurement technique. The scatter in the reported amplitudes is within the range expected for the standard cold dark matter (CDM) cosmological model and results primarily from the restricted sky coverage of each experiment. Within the context of standard CDM, current observations of CMB anisotropy support the detection of an acoustic peak in the CMB power spectrum consistent with baryon density 0.005 < Ωb < 0.078 (95% confidence) for Hubble constant H0 = 50 km s-1 Mpc-1. Flat models (Ωb = 0) are rejected at more than 5 standard deviations. The uncertainties are approximately evenly divided between instrument noise and sample variance arising from the limited sky coverage.