|Wayne Barkhouse speaks on dark energy Friday|
A colloquium presentation, "Shedding Light on Dark Energy," by Wayne Barkhouse, assistant professor of physics, will be given Friday, March 28, at 4 p.m. in 111 Ryan Hall.
One decade ago, the astrophysics community was shaken to its core with the announcement that the expansion rate of the Universe was speeding up rather than slowing down due to gravity. This discovery - corroborated at the time by two independent teams searching for supernovae - indicates that the Universe is filled with a mysterious negative pressure or "dark energy." For the past 10 years, theorists have invoked numerous mechanisms to help explain this force, including Einstein's cosmological constant, extra dimensions, quintessence, and even hypothesizing the breakdown of general relativity on cosmological scales.
To acquire a deeper understanding of dark energy, the Dark Energy Task Force (jointly commissioned by NASA, DOE, and NSF) has recommended that an aggressive program be established to fully characterize dark energy. A part of this process includes support for a new large-area, ground-based optical survey to chart the position and brightness of
several hundred million galaxies out to a redshift of order unity. The leading contender that will satisfy these requirements is the Dark Energy Survey (DES).
The DES is a 5,000-square-degree photometric survey that will image the South Galactic Cap in multiple filters (griz), using a new three-square-degree CCD camera mounted to the Blanco four-meter telescope in Chile. The nature of dark energy will be probed utilizing four independent but complementary techniques: the redshift distribution of galaxy clusters, weak gravitational lensing by large-scale structure, the angular correlation of galaxies as imprinted in the baryon acoustic oscillations, and supernova distances. As a member of the DES, Barkhouse will explain how these techniques will allow us to unravel the mystery of dark energy.