HyRec: A fast and highly accurate primordial hydrogen and helium recombination code

Journal Article · Tue Feb 15 04:00:00 EST 2011 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PHYSREVD.83.043513· OSTI ID:21504963

Ali-Haiemoud, Yacine; Hirata, Christopher M ^[1]

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1. California Institute of Technology, Mail Code 350-17, Pasadena, California 91125 (United States)

We present a state-of-the-art primordial recombination code, HYREC, including all the physical effects that have been shown to significantly affect recombination. The computation of helium recombination includes simple analytic treatments of hydrogen continuum opacity in the He I 2{sup 1}P{sup o}-1{sup 1}S line, the He I]2{sup 3}P{sup o}-1{sup 1}S line, and treats feedback between these lines within the on-the-spot approximation. Hydrogen recombination is computed using the effective multilevel atom method, virtually accounting for an infinite number of excited states. We account for two-photon transitions from 2s and higher levels as well as frequency diffusion in Lyman-{alpha} with a full radiative transfer calculation. We present a new method to evolve the radiation field simultaneously with the level populations and the free electron fraction. These computations are sped up by taking advantage of the particular sparseness pattern of the equations describing the radiative transfer. The computation time for a full recombination history is {approx}2 seconds. This makes our code well suited for inclusion in Monte Carlo Markov chains for cosmological parameter estimation from upcoming high-precision cosmic microwave background anisotropy measurements.

• OSTI ID: 21504963
• Journal Information: Physical Review. D, Particles Fields, Journal Name: Physical Review. D, Particles Fields Journal Issue: 4 Vol. 83; ISSN PRVDAQ; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
ACCOUNTING
ACCURACY
ANISOTROPY
APPROXIMATIONS
ATOMS
BOSONS
CALCULATION METHODS
DIFFUSION
ELECTROMAGNETIC RADIATION
ELECTRONS
ELEMENTARY PARTICLES
ELEMENTS
ENERGY LEVELS
ENERGY TRANSFER
EXCITED STATES
FEEDBACK
FERMIONS
FLUIDS
GASES
HEAT TRANSFER
HELIUM
HYDROGEN
LEPTONS
MARKOV PROCESS
MASSLESS PARTICLES
MICROWAVE RADIATION
MONTE CARLO METHOD
NONMETALS
OPACITY
OPTICAL PROPERTIES
PHOTONS
PHYSICAL PROPERTIES
RADIANT HEAT TRANSFER
RADIATIONS
RARE GASES
RECOMBINATION
RELICT RADIATION
SIMULATION
STOCHASTIC PROCESSES