HyRec: A fast and highly accurate primordial hydrogen and helium recombination code - Astrophysics > Cosmology and Nongalactic AstrophysicsReportar como inadecuado




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Abstract: We present a state-of-the-art primordial recombination code, HyRec, includingall the physical effects that have been shown to significantly affectrecombination. The computation of helium recombination includes simple analytictreatments of hydrogen continuum opacity in the He I 2 1P - 1 1S line, the HeI 2 3P - 1 1S line, and treats feedback between these lines within theon-the-spot approximation. Hydrogen recombination is computed using theeffective multilevel atom method, virtually accounting for an infinite numberof excited states. We account for two-photon transitions from 2s and higherlevels as well as frequency diffusion in Lyman-alpha with a full radiativetransfer calculation. We present a new method to evolve the radiation fieldsimultaneously with the level populations and the free electron fraction. Thesecomputations are sped up by taking advantage of the particular sparsenesspattern of the equations describing the radiative transfer. The computationtime for a full recombination history is ~2 seconds. This makes our code wellsuited for inclusion in Monte Carlo Markov chains for cosmological parameterestimation from upcoming high-precision cosmic microwave background anisotropymeasurements.



Autor: Yacine Ali-Haïmoud, Christopher M. Hirata

Fuente: https://arxiv.org/







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