Radiative transfer effects during primordial helium recombination
Bibliographic record
Abstract
In this paper we refine the calculation of primordial helium recombination, accounting for several additional effects that were neglected or treated more approximately in previous studies. These include consideration of the following: (i) time-dependent radiative transfer interaction between the 21P1–11S0 and 23P1–11S0 resonances; (ii) time-dependent radiative transfer for the partially overlapping n1P1–11S0, n1D2–11S0 and n3P1–11S0 series with 3 ≤n≤ 10; (iii) electron scattering within a kernel approach. We also briefly discuss the effect of electron scattering and H i quadrupole lines on the recombination of hydrogen. Although the physics of all considered processes is interesting and subtle, for the standard cosmology, with helium abundance Yp≃ 0.24, the overall correction to the ionization history during helium recombination with respect to the previous implementation of CosmoRec remains smaller than |ΔNe/Ne| ≃ 0.05 per cent. The dominant improvement is caused by consistent inclusion of resonance scattering for the 21P1–11S0 resonance. For cosmologies with a large helium fraction, Yp≃ 0.4, the difference reaches |ΔNe/Ne| ≃ 0.22 per cent at z≃ 1800; however, the overall correction to the cosmic microwave background power spectra is small, exceeding |ΔCl/Cl| ≃ 0.05 per cent only at l≳ 3000. In comparison to the current version of Recfast the difference reaches |ΔCl/Cl| ≃ 0.4 per cent at l≃ 3000 for Yp≃ 0.4, and also for the standard value Yp≃ 0.24 we find differences of |ΔCl/Cl| ≳ 0.1 per cent at l≃ 2500. The new processes are now included by the cosmological recombination code CosmoRec and can be activated as needed for most settings without affecting its runtime significantly.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.004 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".