Dark Lessons from the Sloan Digital Sky Survey

Abstract

The true nature of dark energy remains unclear: It is either a strange fluid in the Universe, with a negative effective pressure, or a breakdown in General Relativity on large scales. This question can only be answered through a suite of different observations as a function of redshift. In this paper, I will briefly review our attempts to achieve this goal using data from the Sloan Digital Sky Survey (SDSS). In particular, I will present new measurements of the Baryon Acoustic Oscillations (BAO) from the SDSS DR5 galaxy redshift survey as well as outline the on-going SDSSII Supernova Survey, which has already detected (in 2005-06) over 300 SN Ia's over the redshift range 0.05<z<0.4. I will also discuss the latest measurements of the Integrated Sachs-Wolfe (ISW) effect that now probe the density of dark energy at z~1.5. All these measurements are still consistent with a lambda-dominated universe.