Primordial helium recombination. III. Thomson scattering, isotope shifts, and cumulative results

Journal Article · Tue Apr 15 04:00:00 EDT 2008 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PHYSREVD.77.083008· OSTI ID:21249995

Switzer, Eric R; Hirata, Christopher M ^[1]

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1. Department of Physics, Princeton University, Princeton, New Jersey, 08544 (United States)

Upcoming precision measurements of the temperature anisotropy of the cosmic microwave background at high multipoles will need to be complemented by a more complete understanding of recombination, which determines the damping of anisotropies on these scales. This is the third in a series of papers describing an accurate theory of He i and He ii recombination. Here we describe the effect of Thomson scattering, the {sup 3}He isotope shift, the contribution of rare decays, collisional processes, and peculiar motion. These effects are found to be negligible: Thomson and {sup 3}He scattering modify the free electron fraction x{sub e} at the level of severalx10{sup -4}. The uncertainty in the 2{sup 3}P{sup o}-1{sup 1}S rate is significant, and for conservative estimates, gives uncertainties in x{sub e} of order 10{sup -3}. We describe several convergence tests for the atomic level code and its inputs, derive an overall C{sub l} error budget, and relate shifts in x{sub e}(z) to the changes in C{sub l}, which are at the level of 0.5% at l=3000. Finally, we summarize the main corrections developed thus far. The remaining uncertainty from known effects is {approx}0.3% in x{sub e}.

• OSTI ID: 21249995
• Journal Information: Physical Review. D, Particles Fields, Journal Name: Physical Review. D, Particles Fields Journal Issue: 8 Vol. 77; ISSN PRVDAQ; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
79 ASTRONOMY AND ASTROPHYSICS
ANISOTROPY
CONVERGENCE
CORRECTIONS
DAMPING
DECAY
ELECTRONS
HELIUM
HELIUM 3
MULTIPOLES
RECOMBINATION
RELICT RADIATION
SPECTRAL SHIFT
THOMSON SCATTERING