Interpreting CMB Anisotropy Observations: Trying to Tell the Truth with Statistics

A conflict has been reported between the baryon density inferred from deuterium observations and that found from recent CMB observations by BOOMERanG and MAXIMA. Despite the flurry of papers that attempt to resolve this conflict by adding new physics to the early universe, we will show that it can instead be resolved via a more careful usage of statistics. Indeed, the Bayesian analyses that produce this conflict are by their nature poorly suited for drawing this type of conclusion. A properly defined frequentist analysis can address this question directly and appears not to find a conflict. Finally, a conservative accounting of systematic uncertainties in measuring the deuterium abundance could reduce what is nominally a 3 sigma conflict to 1 sigma.Comment: 6 pages, to appear in proceedings of the 20th Texas Symposium on Relativistic Astrophysic

Extracting Primordial Density Fluctuations

The combination of detections of anisotropy in the Cosmic Microwave Background radiation and observations of the large-scale distribution of galaxies probes the primordial density fluctuations of the universe on spatial scales varying by three orders of magnitude. These data are found to be inconsistent with the predictions of several popular cosmological models. Agreement between the data and the Cold + Hot Dark Matter model, however, suggests that a significant fraction of the matter in the universe may consist of massive neutrinos.Comment: 20 pages including 4 color postscript figures. Full-size figures and data compilation available at http://cfpa.berkeley.edu/cmbserve/fluctuations/figures.htm