Cosmological recombination of hydrogen

California Institute Of Technology, Pasadena CA

Investigators

Abstract

Dr. Hirata will undertake a study which will solve for the cosmological recombination history. Without this new recombination calculation, cosmological constraints from the Cosmic Microwave Background will in the near future be limited by the ability to make theoretical predictions, rather than by experimental limitations. Major components of the project include a detailed investigation of many processes that have been previously neglected or considered only in crude or unphysical approximations, including two-photon decays, Raman scattering, Lyman-alpha diffusion, overlap of high-order Lyman lines, and the role of very highly excited levels of the hydrogen atom. The second component will be development of a fast, accurate recombination code suitable for inclusion into CMB prediction software. Broader impacts of this work include research training for graduate students and release of software to the astronomical community.