|
Abstract COSMOLOGY FROM ANTARCTICA Robert W. Wilson Four hundred thousand years after the Big Bang, electrons and nuclei combined to form atoms for the first time, allowing a sea of photons to stream freely through a newly-transparent Universe. After billions of years, those photons, highly redshifted by the universal cosmic expansion, have become the Cosmic Microwave Background Radiation (CMBR) we see coming from all directions today. Observation of the CMBR is central to observational cosmology, and the Antarctic Plateau is an exceptionally good site for this work. The first attempt at CMBR observations from the Plateau was an expedition to the South Pole in December 1986 by the Radio Physic Research group at Bell Laboratories. No CMBR anisotropies were observed, but sky noise and opacity were measured. The results were sufficiently encouraging that in the Austral summer of 1988-1989, three CMBR groups participated in the ``Cucumber'' campaign, where a temporary site dedicated to CMB anisotropy measurements was set up 2 km from South Pole Station. These were summer-only campaigns. Winter-time observations became possible with the establishment in 1990 of the Center for Astrophysical Research in Antarctica (CARA), a National Science Foundation Science and Technology Center. CARA developed year-round observing facilities in the ``Dark Sector'', a section of Amundsen-Scott South Pole Station dedicated to astronomical observations. CARA scientists fielded several astronomical instruments: AST/RO, SPIREX, White Dish, Python, Viper, ACBAR, and DASI (the Degree-Angular Scale Interferometer). By 2001, data from CARA, together with BOOMERANG, a CMBR experiment on a long-duration balloon launched from McMurdo Station on the coast of Antarctica, showed clear evidence that the overall geometry of the Universe is flat, as opposed to being positively or negatively curved. In 2002, the DASI group reported the detection of polarization in the CMBR. These observations strongly support a ``Standard Theory'' of cosmology, where the dynamics of a flat Universe are dominated by forces exerted by the mysterious Dark Energy and Dark Matter. CMBR observations continue on the Antarctic Plateau. The South Pole Telescope (SPT) is a newly-operational 10 m diameter offset telescope designed to rapidly measure anisotropies on scales much smaller than 1°. The Smithsonian Astrophysical Observatory is a collaborator in this important new instrument.
|