The cosmic microwave background (CMB), consisting of photons emitted at the time of recombination and redshifted into microwave frequencies, is a key area of research in the CPAC group. Despite being an almost perfect black-body, small anisotropies have been observed in the microwave sky both in temperature and polarization. These give powerful constraints on the early Universe (through primary anisotropies) as well as the later Universe (through secondary anisotropies).
The CPAC group has strong ties with the South Pole Telescope (SPT) as well as the planned CMB-S4 mission. We have wide interests within the field, including but not limited to cluster detection via the thermal and kinematic Sunyaev-Zeldovich effects, neutrino constraints, and studying the link between optical and microwave observations. See also the CMB @ Argonne site!