{c}

<Yacine Ali-Haïmoud>, with <Christopher M. Hirata>, produced the HyRec model of primordial <hydrogen> and <helium> recombination. It combines an effective multilevel-atom treatment with detailed photon transport while exploiting the sparse coupling structure to make repeated cosmological calculations practical.<HyRec: A fast and highly accurate primordial hydrogen and helium recombination code by Yacine Ali-Haïmoud and Christopher M. Hirata>[Abstract: atomic processes, sparse evolution and parameter-estimation motivation]{ref}

This connects atomic <transition rates> to cosmological inference: a changed recombination history changes the probability that a <cosmic microwave background> photon scatters before reaching the observer.


 Yacine Ali-Haïmoud (source code)