High-resolution and high-sensitivity microwave sky surveys are just beginning, from experiments such as the Atacama Cosmology Telescope (ACT) and the South Pole Telescope (SPT). They will detect thousands of galaxy clusters through the spectral distortion of the microwave background radiation known as the Sunyaev-Zeldovich Effect (SZE). These experiments have the remarkable potential to measure galaxy cluster velocities using a small signal known as the kinetic SZE (kSZ), which would be the first direct determination of velocities for objects at cosmological distances. The cosmic velocity field is a powerful probe of structure growth, since velocities are the direct result of gravitational instability. Early studies were generally inconclusive because of large systematic errors. This project is a comprehensive theoretical, phenomenological, and observational study of galaxy cluster velocities, including (1) characterization of the cosmological information; (2) statistical methods for extracting it; (3) calculating the impact of systematic errors; (4) improved calculations of model predictions for the cluster velocity and momentum statistics; (5) studying the accuracy with which cluster velocities and momenta may be extracted from observations in different wave bands; and (6) cluster peculiar velocities and momenta from the ACT experiment. This newly accessible source of cosmological information is a novel probe of the formation of structure in the Universe, providing independent tests of the standard model in cosmology and better determining several fundamental parameters.
The project includes educational initiatives at a range of levels, including mentoring of a graduate student; involving undergraduates in the research effort; and secondary education and public outreach efforts in cooperation with the Allegheny Observatory.
