Recombinations to the Rydberg States of Hydrogen and Their Effect During the Cosmological Recombination Epoch

Understand

In this paper we discuss the effect of recombinations to highly excited states (n > 100) in hydrogen during the cosmological recombination epoch.

• For this purpose, we developed a new ODE solver for the recombination problem, based on an implicit Gear's method.
• This solver allows us to include up to 350 l-resolved shells or ~61 000 separate levels in the hydrogen model and to solve the recombination problem for one cosmology in ~27 hours.
• This is a huge improvement in performance over our previous recombination code, for which a 100-shell computation (5050 separate states) already required ~150 hours on a single processor.