South Pole Telescope - Science Goals

Science Goals

The first key project for the SPT, completed in October, 2011, was a 2500-square degree survey to search for clusters of galaxies using the Sunyaev-Zel'dovich effect, a distortion of the cosmic microwave background radiation (CMB) due to interactions between CMB photons and the hot, ionized gas in clusters. The survey has found hundreds of clusters of galaxies over an extremely wide redshift range. When combined with accurate redshifts and mass estimates for the clusters, this survey will place interesting constraints on the Dark Energy equation of state.

The main science goal of the current SPTpol camera is to measure so-called "B-mode" or "curl" component of the polarized CMB. This B-mode signal is generated at small angular scales by the gravitational lensing of the much larger primordial "E-mode" polarization signal (generated by scalar density perturbations at the time the CMB was emitted) and at large angular scales by the interaction of the CMB with a background of gravitational waves produced during the epoch of inflation. Measurements of the small-scale B-mode signal can place stringent constraints on the growth of structure between the time the CMB was emitted and today, and, in doing so, constrain cosmological parameters that influence structure growth, including the sum of the neutrino masses. Measurements of the large-scale B-mode signal have the potential to constrain the energy scale of inflation, thus probing the physics of the universe at the earliest times and highest energy scales imaginable.

The Atacama Cosmology Telescope has similar, but complementary, science objectives.