Prof. Yoel Rephaeli pursues a range of topics in cosmology and high-energy astrophysics, including: properties of the cosmic microwave background (CMB) radiation; calculations of spectral and spatial signatures produced by the interaction of the CMB with hot gas in galaxy clusters; use of galaxy clusters as improved cosmological probes by joint, multi-spectral analyses of current and future microwave, optical, and X-ray measurements; studies of non-thermal phenomena (e.g., energetic particles, magnetic fields) in star-forming galaxies, radio galaxies, and galaxy clusters by comparisons of predictions from modeling the particle spectro-spatial distributions and their radiative yields (from all relevant leptonic and hadronic processes) with radio, X-ray, and gamma-ray measurements.

Research achievements include: dynamical analyses of mass profiles of several galaxy clusters; development of a new expanded merger-tree description of galaxy cluster evolution; neutrino mass inference from surveys of CMB signatures imprinted by Compton scattering in galaxy clusters; successful prediction of the level of gamma-ray emission in nearby starburst galaxies (measured by the Fermi satellite).