Future Cosmic Microwave Background Constraints to the Baryon Density

Abstract

We discuss what can be learned about the baryon density from an all-sky map of the cosmic microwave background (CMB) with sub-degree angular resolution. With only minimal assumptions about the primordial spectrum of density perturbations and the values of other cosmological parameters, such a CMB map should be able to distinguish between a Universe with a baryon density near 0.1 and a baryon-dominated Universe. With additional reasonable assumptions, it is conceivable that such measurements will constrain the baryon density to an accuracy similar to that obtained from BBN calculations.

4 pages. To appear in the proceedings of the Cosmic Abundances Conference, College Park, MD, October 9--11, 1995, edited by S. S. Holt and G. Sonneborn (AIP, New York, 1996)