The South Pole Telescope (SPT) is designed to study the Cosmic Microwave Background (CMB) radiation at small angular scales. Chief amongst our science goals during the first few years of operation is to survey 4000 square degrees of the night sky (about 10% of the sky) for the signature galaxy clusters leave on the CMB through the Sunyaev-Zel'dovich effect (SZe). The resultant galaxy cluster catalog will allow us to explore the effect dark energy has on the expansion history of the universe. These new measurements will shed light on the surprising and mysterious dark energy phenomena that acts like an "anti-gravity" force, causing the universe to accelerate its expansion.
The South Pole Telescope was deployed to the Amundsen-Scott Polar Research Station at the geographic South Pole from November 2006-February 2007 (the deployment team is shown at left). It took about 120 Hercules C130 aircraft flights for the U.S. National Guard to transport the telescope. The South Pole is perhaps the best location for performing mm-wavelength observations because of its high altitude (about 3000m), very low atmospheric water vapour content, and stable weather patterns. There are, nonetheless, some pretty extreme challenges to doing science at one of the least hospitable locations on the planet. Winter temperatures dip below -80C and the station is inaccessible from mid-February to November each year- our winter-over team is completely isolated during this time.
The SPT is a 10m off-axis Gregorian telescope. The focal plane, cooled to 250 mK with a combination of a mechanical pulse tube cooler and closed cycle 3He, 3He, 4He absorption refrigerator, contains 960 Transition Edge Sensor bolometers. We observe with 1 arcminute FWHM beams across a 1 degree field of view, with bands centered on 90, 150, and 220 GHz. The SPT secondary mirror is cooled to 10K in the cryostat (white) which is being mated to the bolometric receiver (red) in the photo at right. The key technologies of the SPT receiver closely mirror those of the APEX-SZ experiment, which in many ways is a pathfinder for the SPT. Unlike APEX-SZ, 100% of the SPT observation time is dedicated to our CMB science goals.
The South Pole Telescope is a collaboration between U. Chicago (lead institution, PI John Carlstrom), U.C. Berkeley, U. Illinois, Case Western Reserve U., Jet Propulsion Lab, Harvard-Smithsonian, McGill U., C.U. Boulder, and U.C. Davis.
Our team at McGill University includes Prof. Matt Dobbs who co-lead the development and deployment of the multiplexed readout (shown right), Prof. Gil Holder who specializes in SZ theory, simulations, and analysis techniques, and their research groups.
- The SPT Collaboration (Z. Staniszewski et al.), "Galaxy Clusters Discovered with a Sunyaev-Zel'Dovich Effect Survey", submitted to ApJ, October 2008 [astro-ph/0810.1578]. (first discovery of galaxy clusters using SZe)
- The SPT Collaboration (John E. Ruhl et al.), "The South Pole Telescope", Millimeter and Submillimeter Detectors for Astronomy II, Proceedings of the SPIE, Volume 5498, (2004) 11-29 [astro-ph/0411122].
- M. Dobbs for the SPT Collaboration, "First Light for the South Pole Telescope", Newsletter for the Canadian Antarctic Research Network,Volume 23, May 2007. (plain language description of the deployment & telescope)