Two-photon transitions in primordial hydrogen recombination

Hirata, Christopher M.

doi:10.1103/physrevd.78.023001

Cited by 82 publications

(225 citation statements)

References 53 publications

Supporting

Mentioning

212

Contrasting

Order By: Relevance

“…III.C of Hirata 2008) for the decay rates. As pointed out, this distinction is not unique, but the results were shown to be independent of the chosen parameters (Hirata 2008), in total yielding ΔN e /N e ∼ +1.3% at z ∼ 900 and ΔN e /N e ∼ −1.3% at z ∼ 1300.…”

Section: Introductionmentioning

confidence: 92%

“…As explained in several previous studies (Chluba & Sunyaev 2009c;Switzer & Hirata 2008;Rubiño-Martín et al 2008;Hirata 2008) for the conditions in our Universe (practically no collisions), this is a much better description than the assumption of complete redistribution, which is used in deriving of the Sobolev escape probability. We also take into account stimulated 3s-1s and 3d-1s two-photon emission, finding this process to be subdominant.…”

Section: Introductionmentioning

confidence: 99%

“…Another investigation of the two-photon aspects of the recombination problem was performed by Hirata (2008). He gave a formulation of the photon transfer problem simultaneously including all two-photon corrections during hydrogen recombination related to ns-1s, nd-1s, and c-1s transitions and Raman scattering processes, also taking into account stimulated processes in the ambient CMB blackbody radiation field.…”

Section: Introductionmentioning

confidence: 99%

“…However, the calculation of Cresser et al (1986) was incomplete, since in their attempt to separate the "1 + 1" photon contributions to the two-photon formula 2 from the "pure" twophoton decay terms, without clear justification they neglected the first non-resonant term . Physically, it seems very difficult to separate the "pure" two-photon decay rate from the "1 + 1" resonant contributions (see discussions in Hirata 2008;Karshenboim & Ivanov 2008;Labzowsky et al 2009;Jentschura 2009), e.g., because of non-classical interference effects. In a complete analysis, these contributions should be taken into account.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Lyαescape during cosmological hydrogen recombination: the 3d-1s and 3s-1s two-photon processes

Chluba

Sunyaev

2010

A&A

View full text Add to dashboard Cite

We give a formulation of the radiative transfer equation for Lyman α photons, which allows us to include the two-photon corrections for the 3s-1s and 3d-1s decay channels during cosmological hydrogen recombination. We use this equation to compute the corrections to the Sobolev escape probability for Lyman α photons during hydrogen recombination, which then allow us to calculate the changes in the free electron fraction and CMB temperature and polarization power spectra. We show that the effective escape probability changes by ΔP/P ∼ +11% at z ∼ 1400 in comparison with the one obtained using the Sobolev approximation. This accelerates hydrogen recombination by ΔN e /N e ∼ −1.6% at z ∼ 1190, implying that |ΔC l /C l | ∼ 1−3% at l > ∼ 1500 with shifts in the positions of the maxima and minima in the CMB power spectra. These corrections will be important to the analysis of future CMB data. The total correction is the result of the superposition of three independent processes, related to (i) time-dependent aspects of the problem; (ii) corrections due to quantum mechanical deviations in the shape of the emission and absorption profiles in the vicinity of the Lyman α line, from the normal Lorentzian; and (iii) a thermodynamic correction factor, which is found to be very important. All of these corrections are neglected in the Sobolev-approximation, but they are important in the context of future CMB observations. All three can be naturally obtained in the two-photon formulation of the Lyman α absorption process. However, the corrections (i) and (iii) can also be deduced in the normal "1 + 1" photon language, without necessarily going to the two-photon picture. Therefore, only (ii) is really related to the quantum mechanical aspects of the two-photon process. We show here that (i) and (iii) represent the largest individual contributions to the result, although they partially cancel each other close to z ∼ 1100. At z ∼ 1100, the modification due to the shape of the line profile contributes about ΔN e /N e ∼ −0.4%, while the sum of the other two contributions gives ΔN e /N e ∼ −0.9%.

show abstract

Section: Introductionmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Lyαescape during cosmological hydrogen recombination: the 3d-1s and 3s-1s two-photon processes

Chluba

Sunyaev

2010

A&A

View full text Add to dashboard Cite

show abstract

“…Hirata (2008) also included the two-photon decays from higher levels in hydrogen and 2s-1s Raman scattering. The former lead to an additional speed up of hydrogen recombination at the level of ∆N e /N e ∼ 0.1% − 0.3%, while the Raman process leads to an additional delay of recombination by ∆N e /N e ∼ 0.9% at z ∼ 900.…”

Section: Additional Processes During Hydrogen Recombinationmentioning

confidence: 99%

Signals From the Epoch of Cosmological Recombination

Sunyaev

Chluba

2009

Reviews in Modern Astronomy

View full text Add to dashboard Cite

The physical ingredients to describe the epoch of cosmological recombination are amazingly simple and well-understood. This fact allows us to take into account a very large variety of physical processes, still finding potentially measurable consequences for the energy spectrum and temperature anisotropies of the Cosmic Microwave Background (CMB). In this contribution we provide a short historical overview in connection with the cosmological recombination epoch and its connection to the CMB. Also we highlight some of the detailed physics that were studied over the past few years in the context of the cosmological recombination of hydrogen and helium.The impact of these considerations is two-fold: (i) the associated release of photons during this epoch leads to interesting and unique deviations of the Cosmic Microwave Background (CMB) energy spectrum from a perfect blackbody, which, in particular at decimeter wavelength and the Wien part of the CMB spectrum, may become observable in the near future. Despite the fact that the abundance of helium is rather small, it still contributes a sizeable amount of photons to the full recombination spectrum, leading to additional distinct spectral features. Observing the spectral distortions from the epochs of hydrogen and helium recombination, in principle would provide an additional way to determine some of the key parameters of the Universe (e.g. the specific entropy, the CMB monopole temperature and the pre-stellar abundance of helium). Also it permits us to confront our detailed understanding of the recombination process with direct observational evidence. In this contribution we illustrate how the theoretical spectral template of the cosmological recombination spectrum may be utilized for this purpose. We also show that because hydrogen and helium recombine at very different epochs it is possible to address questions related to the thermal history of our Universe. In particular the cosmological recombination radiation may allow us to distinguish between Compton y-distortions that were created by energy release before or after the recombination of the Universe finished. 1(ii) with the advent of high precision CMB data, e.g. as will be available using the Planck Surveyor or CMBpol, a very accurate theoretical understanding of the ionization history of the Universe becomes necessary for the interpretation of the CMB temperature and polarization anisotropies. Here we show that the uncertainty in the ionization history due to several processes, which until now were not taken in to account in the standard recombination code Recfast, reaches the percent level. In particular He ii → He i-recombination occurs significantly faster because of the presence of a tiny fraction of neutral hydrogen at z 2400. Also recently it was demonstrated that in the case of H i Lyman α photons the timedependence of the emission process and the asymmetry between the emission and absorption profile cannot be ignored. However, it is indeed surprising how inert the cosmological recombination hi...

show abstract

Signals from the epoch of cosmological recombination – Karl Schwarzschild Award Lecture 2008

2009

View full text Add to dashboard Cite

Key words cosmic microwave background -cosmological parameters -early universeThe physical ingredients to describe the epoch of cosmological recombination are amazingly simple and well-understood. This fact allows us to take into account a very large variety of physical processes, still finding potentially measurable consequences for the energy spectrum and temperature anisotropies of the Cosmic Microwave Background (CMB). In this contribution we provide a short historical overview in connection with the cosmological recombination epoch and its connection to the CMB. Also we highlight some of the detailed physics that were studied over the past few years in the context of the cosmological recombination of hydrogen and helium. The impact of these considerations is two-fold: (i) The associated release of photons during this epoch leads to interesting and unique deviations of the Cosmic Microwave Background (CMB) energy spectrum from a perfect blackbody, which, in particular at decimeter wavelength and the Wien part of the CMB spectrum, may become observable in the near future. Despite the fact that the abundance of helium is rather small, it still contributes a sizeable amount of photons to the full recombination spectrum, leading to additional distinct spectral features. Observing the spectral distortions from the epochs of hydrogen and helium recombination, in principle would provide an additional way to determine some of the key parameters of the Universe (e.g. the specific entropy, the CMB monopole temperature and the pre-stellar abundance of helium). Also it permits us to confront our detailed understanding of the recombination process with direct observational evidence. In this contribution we illustrate how the theoretical spectral template of the cosmological recombination spectrum may be utilized for this purpose. We also show that because hydrogen and helium recombine at very different epochs it is possible to address questions related to the thermal history of our Universe. In particular the cosmological recombination radiation may allow us to distinguish between Compton y-distortions that were created by energy release before or after the recombination of the Universe finished.(ii) With the advent of high precision CMB data, e.g. as will be available using the PLANCK Surveyor or CMBPOL, a very accurate theoretical understanding of the ionization history of the Universe becomes necessary for the interpretation of the CMB temperature and polarization anisotropies. Here we show that the uncertainty in the ionization history due to several processes, which until now were not taken in to account in the standard recombination code RECFAST, reaches the percent level. In particular He ii → He i recombination occurs significantly faster because of the presence of a tiny fraction of neutral hydrogen at z < ∼ 2400. Also recently it was demonstrated that in the case of H I Lyman α photons the timedependence of the emission process and the asymmetry between the emission and absorption profile cannot be ignored. How...

show abstract

Two-photon transitions in primordial hydrogen recombination

Cited by 82 publications

References 53 publications

Lyαescape during cosmological hydrogen recombination: the 3d-1s and 3s-1s two-photon processes

Lyαescape during cosmological hydrogen recombination: the 3d-1s and 3s-1s two-photon processes

Signals From the Epoch of Cosmological Recombination

Signals from the epoch of cosmological recombination – Karl Schwarzschild Award Lecture 2008

Contact Info

Product

Resources

About