Physics & Astronomy Colloquium

3:30 PM, Friday, October 5, 2007
Room 155, Chem-Phys Building

Dr. Jim Braatz
National Radio Astronomy Observatory
Green Bank, West Virginia

"Megamasers and Cosmology''

As a complement to observations of the Cosmic Microwave Background, a precise measurement of the Hubble constant would provide a valuable constraint on several key cosmological parameters, including the equation of state of dark energy. The best measurements of the Hubble constant are currently based on standard candle observations and are limited by systematic uncertainties. I will describe an ambitious project that aims to measure the Hubble constant by measuring distances to galaxies using a geometric technique based on observations of water vapor megamasers in AGN accretion disks. I will show early results for a few galaxies and discuss the prospects for applying the technique to others.

Refreshments will be served in CP 179 at 3:15 PM