An asymptotic expression for the dipole oscillator strength for transitions of the He sequence

Khandelwal, G. S.; Khan, F.; Wilson, J. Warren

doi:10.1086/167028

Cited by 11 publications

(5 citation statements)

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“…[15,16] for n ≤ 9 and used the asymptotic formula of Ref. [17] for n > 9. For the continuum states we used the TOPbase cross sections [18], which are trivially converted into oscillator strengths.…”

Section: Rayleigh Scattering Cross Sectionmentioning

confidence: 99%

Effects of Rayleigh scattering on the CMB and cosmic structure

2015

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During and after recombination, in addition to Thomson scattering with free electrons, photons also coupled to neutral hydrogen and helium atoms through Rayleigh scattering. This coupling influences both CMB anisotropies and the distribution of matter in the Universe. The frequencydependence of the Rayleigh cross section breaks the thermal nature of CMB temperature and polarization anisotropies and effectively doubles the number of variables needed to describe CMB intensity and polarization statistics, while the additional atomic coupling changes the matter distribution and the lensing of the CMB. We introduce a new method to capture the effects of Rayleigh scattering on cosmological power spectra. Rayleigh scattering modifies CMB temperature and polarization anisotropies at the ∼ 1% level at 353GHz (scaling ∝ ν 4 ), and modifies matter correlations by as much as ∼ 0.3%. We show the Rayleigh signal, especially the cross-spectra between the thermal (Rayleigh) E-polarization and Rayleigh (thermal) intensity signal, may be detectable with future CMB missions even in the presence of foregrounds, and how this new information might help to better constrain the cosmological parameters.

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Section: Rayleigh Scattering Cross Sectionmentioning

confidence: 99%

Effects of Rayleigh scattering on the CMB and cosmic structure

2015

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“…For 1 1 S − n 1 P o transitions (n < 10), we use the asymptotic formula of Ref. [80]. (This formula is only 1.4% different from TOPbase at n = 10.)…”

Section: He I Model Atommentioning

confidence: 99%

Primordial helium recombination. I. Feedback, line transfer, and continuum opacity

Switzer

Hirata

2008

Phys. Rev. D

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Precision measurements of the cosmic microwave background temperature anisotropy on scales ' > 500 will be available in the near future. Successful interpretation of these data is dependent on a detailed understanding of the damping tail and cosmological recombination of both hydrogen and helium. This paper and two companion papers are devoted to a precise calculation of helium recombination. We discuss several aspects of the standard recombination picture, and then include feedback, radiative transfer in He I lines with partial redistribution, and continuum opacity from H I photoionization. In agreement with past calculations, we find that He II recombination proceeds in Saha equilibrium, whereas He I recombination is delayed relative to Saha due to the low rates connecting excited states of He I to the ground state. However, we find that at z < 2200 the continuum absorption by the rapidly increasing H I population becomes effective at destroying photons in the He I 2 1 P o ÿ 1 1 S line, causing He I recombination to finish around z 1800, much earlier than previously estimated.

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“…Equation (l), although found to be suitable for the work presented in this paper, is not appropriate for the transitions with n = n' (because of the method of going from the continuum to discrete in the dipole case in the original work (Khandelwal et al 1989). For such transitions, equation (1) should not be employed.…”

Section: Hydrogenic Radial Integral and Asymptotic Expansionmentioning

confidence: 96%

Asymptotic expansions of the hydrogenic radial dipole integral

Dubey¹,

Khandelwal²,

Pritchard³

1991

J. Phys. B: At. Mol. Opt. Phys.

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A method is presented for an asymptotic expansion of the hydrogenic radial dipole integral for discrete-discrete transitions from initial state n'l' to final state nl. The advantage of this simple method is that it allows all the necessary algebraic manipulations to be done by the computer programming package REDUCE-2. Expansion coefficients up to the coefficient of the l/n17 term are obtained for all initial states with n' < or = 10. However, only the coefficients which are not calculated by Klarsfeld are tabulated in this paper.

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An asymptotic expression for the dipole oscillator strength for transitions of the He sequence

Cited by 11 publications

References 0 publications

Effects of Rayleigh scattering on the CMB and cosmic structure

Effects of Rayleigh scattering on the CMB and cosmic structure

Primordial helium recombination. I. Feedback, line transfer, and continuum opacity

Asymptotic expansions of the hydrogenic radial dipole integral

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