Brown University

Title: FIRST YEAR RESULTS FROM THE WILKINSON MICROWAVE ANISOTROPY PROBE (WMAP)

Abstract: WMAP was launched on 30 June 2001, and the first year of observations are complete. WMAP has ushered in a new era of precision cosmology.

The best fit model from WMAP data indicates the universe is 13.7 billion years old (with an error of less than 2%), and that it will
expand forever. The WMAP data also indicate the universe is composed of 4.4% baryons, 22% dark matter and 73% dark energy. Perhaps the most surprising result from WMAP is the first stars appear to have turned on 200 million years after the Big Bang, much earlier than thought previously. The data also place contraints on inflationary models and rules out some of these.

The results are consistent with those from the Cosmic Microwave Background (COBE), which first detected anisotropy in the cosmic microwave background in 1992, but have greatly improved resolution and sensitivity. The high quality sky maps from WMAP are the result of a careful experimental design that minimizes systematic effects and enables thorough instrumental characterization and calibration.