Colloquium presentation by Dr. Wayne Barkhouse: "Shedding Light on Dark Energy" Friday, March 28th at 4 p.m.
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 5000 square degree photometric survey that will image the
South Galactic Cap in multiple filters (griz), using a new 3 sq. deg.
CCD camera mounted to the Blanco 4-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, I will
explain how these techniques will allow us to unravel the mystery of