General Physics Colloquium, Dr. Joshua Frieman, Fermilab and the University of Chicago
Refreshments from 3:30-3:50 pm
Title: Probing Cosmic Acceleration with the Dark Energy Survey
Host: Jim Alexander
Abstract: Why is the expansion of the universe speeding up? Is cosmic acceleration due to dark energy or does it require a modification of General Relativity? If it’s due to dark energy, is it the energy density of the vacuum (Einstein's cosmological constant) or something else? To address these questions, the Dark Energy Survey (DES) collaboration built the 570-megapixel Dark Energy Camera for the Blanco 4-meter telescope at NOAO's Cerro Tololo Inter-American Observatory in Chile, to carry out a 5-year, deep, multi-band, optical survey of several hundred million galaxies and several thousand supernovae. DES is measuring the history of cosmic expansion and the growth of structure through four complementary techniques: galaxy clusters, the large-scale galaxy distribution, gravitational lensing, and supernovae, as well as through cross-correlation with other data sets. The DES survey began in August 2013 and recently completed its fourth observing season; this talk will highlight the project’s early results and discuss how the data are being used to make a variety of astronomical discoveries, from the outer Solar System to the most distant quasars.