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Friday, September 25, 2009
Physics Building, Room 204
Note special time.
[Host: PQ Hung]
"Dark Energy and the Hubble Constant"
Dark energy dominates the expansion of the universe and will determine
its ultimate fate. The best complement to cosmic microwave background
data for constraining the nature of dark energy is an accurate
measurement of the current expansion rate (Hubble constant). The goal
of the Megamaser Cosmology Project is to measure the Hubble constant
by using the Green Bank Telescope and the Very Long Baseline Array to
discover and image 22 GHz water masers orbiting the nuclei of Seyfert
galaxies. We can show that these compact nuclei contain supermassive
black holes, not just dense clusters of stars, and determine their
masses. In the past year we improved our measurement of the
angular-size distance to the galaxy UGC 3789, imaged four more masing
galaxies, and derived a preliminary estimate for the Hubble constant.
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