Radiative transfer effects in primordial hydrogen recombination

Journal Article · Wed Dec 15 04:00:00 EST 2010 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PHYSREVD.82.123502· OSTI ID:21513038

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

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

The calculation of a highly accurate cosmological recombination history has been the object of particular attention recently, as it constitutes the major theoretical uncertainty when predicting the angular power spectrum of cosmic microwave background anisotropies. Lyman transitions, in particular the Lyman-{alpha} line, have long been recognized as one of the bottlenecks of recombination, due to their very low escape probabilities. The Sobolev approximation does not describe radiative transfer in the vicinity of Lyman lines to a sufficient degree of accuracy, and several corrections have already been computed in other works. In this paper, we compute the impact of some radiative transfer effects that were previously ignored, or for which previous treatments were incomplete. First, the effect of Thomson scattering in the vicinity of the Lyman-{alpha} line is evaluated, using a full redistribution kernel incorporated into a radiative transfer code. The effect of feedback of distortions generated by the optically thick deuterium Lyman-{alpha} line blueward of the hydrogen line is investigated with an analytic approximation. It is shown that both effects are negligible during cosmological hydrogen recombination. Second, the importance of high-lying, nonoverlapping Lyman transitions is assessed. It is shown that escape from lines above Ly{gamma} and frequency diffusion in Ly{beta} and higher lines can be neglected without loss of accuracy. Third, a formalism generalizing the Sobolev approximation is developed to account for the overlap of the high-lying Lyman lines, which is shown to lead to negligible changes to the recombination history. Finally, the possibility of a cosmological hydrogen recombination maser is investigated. It is shown that there is no such maser in the purely radiative treatment presented here.

• OSTI ID: 21513038
• Journal Information: Physical Review. D, Particles Fields, Journal Name: Physical Review. D, Particles Fields Journal Issue: 12 Vol. 82; ISSN PRVDAQ; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
ACCURACY
AMPLIFIERS
ANISOTROPY
APPROXIMATIONS
CALCULATION METHODS
COMPUTERIZED SIMULATION
CORRECTIONS
COSMOLOGICAL MODELS
DEUTERIUM
DIFFUSION
ELECTROMAGNETIC RADIATION
ELECTRONIC EQUIPMENT
ELEMENTS
ENERGY TRANSFER
EQUIPMENT
FEEDBACK
HEAT TRANSFER
HYDROGEN
HYDROGEN ISOTOPES
INELASTIC SCATTERING
ISOTOPES
KERNELS
LIGHT NUCLEI
LYMAN LINES
MASERS
MATHEMATICAL MODELS
MICROWAVE AMPLIFIERS
MICROWAVE EQUIPMENT
MICROWAVE RADIATION
NONMETALS
NUCLEI
ODD-ODD NUCLEI
PROBABILITY
RADIANT HEAT TRANSFER
RADIATIONS
RECOMBINATION
RELICT RADIATION
SCATTERING
SIMULATION
SPECTRA
STABLE ISOTOPES
THOMSON SCATTERING