# Particle Physics Seminar

## "Sharpening our Focus on Dark Energy with Baryon Acoustic Oscillations"

#### Presented by Nikhil Padmanabhan, Yale University

Thursday, November 17, 2011, 3:00 pm — Small Seminar Room, Bldg. 510

The mysterious acceleration in the expansion rate of the Universe in recent times is one of the foremost puzzles in cosmology today. It signals either a new component that dominates the energy budget of the Universe, or a breakdown in our theory of gravity at cosmological scales. The baryon acoustic oscillation (BAO) method is one of the most robust tools to attack this problem in the modern cosmologist's toolbox. I will introduce this method, and then discuss some of the complications introduced by the nonlinear evolution of density fluctuations and galaxy formation, and why we believe the BAO method is robust to these. I will then present results from a recent 2% measurement of the distance to z=0.35 with the Sloan Digital Sky Survey, aided by a new analysis technique that improved the distance accuracy by a factor of close to 2. I will finally put all of this into the context of ongoing surveys like the Baryon Oscillation Spectroscopic Survey (BOSS), as well as proposed surveys like BigBOSS.

Hosted by: Anze Slosar

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