Cosmology and Nongalactic Astrophysics · arXiv:1308.2100 v1 · submitted 9 Aug 2013
Primordial 4He abundance: a determination based on the largest sample of HII regions with a methodology tested on model HII regions
The paper says
“The derived value of Yp is higher at the 68% confidence level (CL) than that predicted by the standard big bang nucleosynthesis (SBBN) model, possibly implying the existence of different types of neutrino species in addition to the three known types of active neutrinos.”
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Abstract
We verified the validity of the empirical method to derive the 4He abundance used in our previous papers by applying it to CLOUDY (v13.01) models. Using newly published HeI emissivities, for which we present convenient fits as well as the output CLOUDY case B hydrogen and HeI line intensities, we found that the empirical method is able to reproduce the input CLOUDY 4He abundance with an accuracy of better than 1%. The CLOUDY output data also allowed us to derive the non-recombination contribution to the intensities of the strongest Balmer hydrogen Halpha, Hbeta, Hgamma, and Hdelta emission lines and the ionisation correction factors for He. With these improvements we used our updated empirical method to derive the 4He abundances and to test corrections for several systematic effects in a sample of 1610 spectra of low-metallicity extragalactic HII regions, the largest sample used so far. From this sample we extracted a subsample of 111 HII regions with Hbeta equivalent width EW(Hbeta) > 150A, with excitation parameter x = O^2+/O > 0.8, and with helium mass fraction Y derived with an accuracy better than 3%. With this subsample we derived the primordial 4He mass fraction Yp = 0.254+/-0.003 from linear regression Y-O/H. The derived value of Yp is higher at the 68% confidence level (CL) than that predicted by the standard big bang nucleosynthesis (SBBN) model, possibly implying the existence of different types of neutrino species in addition to the three known types of active neutrinos. Using the most recently derived primordial abundances D/H = (2.60+/-0.12)x10^-5 and Yp = 0.254+/-0.003 and the chi^2 technique, we found that the best agreement between abundances of these light elements is achieved in a cosmological model with baryon mass density Omegab h^2 = 0.0234+/-0.0019 (68% CL) and an effective number of the neutrino species Neff = 3.51+/-0.35 (68% CL).
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abstract compiled · 2026-09-23 · no language-model review
How the main claim is stated: hedged possibility 0.90
What the abstract itself states, as probabilities: claims first 0.15 · states limitation 0.42 · human participants 0.01 · controlled comparison 0.18 · randomized assignment 0.01 · states quantitative result 0.99 · compares with prior results 0.88 · mentions code or data availability 0.10
The abstract, sentence by sentence
This table labels the abstract only (arXiv listing abstract v1). The number is the probability the classifier gave the label.
| Sentence | Role | The authors' own work | States the main conclusion | Strength |
|---|---|---|---|---|
| We verified the validity of the empirical method to derive the 4He abundance used in our previous papers by applying it to CLOUDY (v13.01) models. | method 0.75 | 0.95 | 0.03 | asserted 1.00 |
| Using newly published HeI emissivities, for which we present convenient fits as well as the output CLOUDY case B hydrogen and HeI line intensities, we found that the empirical method is able to reproduce the input CLOUDY 4He abundance with an accuracy of better than 1%. | result 0.74 | 0.96 | 0.05 | asserted 1.00 |
| The CLOUDY output data also allowed us to derive the non-recombination contribution to the intensities of the strongest Balmer hydrogen Halpha, Hbeta, Hgamma, and Hdelta emission lines and the ionisation correction factors for He. | method 0.44 | 0.95 | 0.02 | asserted 1.00 |
| With these improvements we used our updated empirical method to derive the 4He abundances and to test corrections for several systematic effects in a sample of 1610 spectra of low-metallicity extragalactic HII regions, the largest sample used so far. | contribution 0.61 | 0.97 | 0.06 | asserted 1.00 |
| From this sample we extracted a subsample of 111 HII regions with Hbeta equivalent width EW(Hbeta) > 150A, with excitation parameter x = O^{2+}/O > 0.8, and with helium mass fraction Y derived with an accuracy better than 3%. | method 0.93 | 0.96 | 0.03 | asserted 0.99 |
| With this subsample we derived the primordial 4He mass fraction Yp = 0.254+/-0.003 from linear regression Y-O/H. | result 1.00 | 0.98 | 0.62 | asserted 1.00 |
| The derived value of Yp is higher at the 68% confidence level (CL) than that predicted by the standard big bang nucleosynthesis (SBBN) model, possibly implying the existence of different types of neutrino species in addition to the three known types of active neutrinos. | interpretation 0.99 | 0.91 | 0.57 | hedged possibility 0.90 |
| Using the most recently derived primordial abundances D/H = (2.60+/-0.12)x10^{-5} and Yp = 0.254+/-0.003 and the chi^2 technique, we found that the best agreement between abundances of these light elements is achieved in a cosmological model with baryon mass density Omegab h^2 = 0.0234+/-0.0019 (68% CL) and an effective number of the neutrino species Neff = 3.51+/-0.35 (68% CL). | result 0.97 | 0.95 | 0.19 | asserted 1.00 |
What kind of paper the classifier reports this is: empirical study 0.97 · evidence from analysis of existing data 0.91
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Compiled by classifier-1.13-20260917 via OpenRouter, question bank abstract-p1-20260923, 2026-09-23: 1 request, 7,014 input tokens, $0.0003 reported.
Every quoted sentence on this record is the authors'. Every label is from Pith's closed vocabulary, with the probability shown beside it. This record as JSON
Cited by 17 Pith papers
Reviewed papers on Pith that cite this one. The full citation record
- Something new under the Sun: A magnetically driven CH/CN anti-correlation astro-ph.SR · Aug 2026
- Detecting non-relativistic cosmic neutrinos by capture on tritium: phenomenology and physics potential hep-ph · May 2014
- Precision measures of the primordial abundance of deuterium astro-ph.CO · Aug 2013
- Ruling out the light WIMP explanation of the galactic 511 keV line astro-ph.CO · Feb 2016
- Improving Helium Abundance Determinations with Leo P as a Case Study astro-ph.CO · Oct 2020
- Improved BBN constraints on Heavy Neutral Leptons hep-ph · Aug 2020
- Big-Bang Nucleosynthesis After Planck astro-ph.CO · Dec 2019
- Big Bang Nucleosynthesis: 2015 astro-ph.CO · May 2015
- Revisiting the bound on axion-photon coupling from Globular Clusters astro-ph.SR · Jun 2014
- Neutrinos help reconcile Planck measurements with both Early and Local Universe astro-ph.CO · Mar 2014
- Sterile neutrinos help reconcile the observational results of primordial gravitational waves from Planck and BICEP2 astro-ph.CO · Mar 2014
- Tight bonds between sterile neutrinos and dark matter hep-ph · Dec 2013
- Dark Radiation constraints on minicharged particles in models with a hidden photon hep-ph · Nov 2013
- Relic Neutrinos, thermal axions and cosmology in early 2014 astro-ph.CO · Mar 2014
- The primordial helium abundance from updated emissivities astro-ph.CO · Aug 2013
- Astrophysical Axion Bounds: The 2024 Edition hep-ph · Jan 2024
- Big-Bang Nucleosynthesis astro-ph.CO · Dec 2014
How the literature uses it
20 arXiv papers cite this in 38 sentences
Papers citing it · 17 sentences without a confident label
Uses its method or tool 1 paper
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The model used to determine the 4 abundance contains eight physical parameters, including the 4 abundance, that is used to predict a set of ten H and He emission line ratios, which can be compared with observations [ref] .
Big Bang Nucleosynthesis: 2015 · Introduction · 0.85
Uses its data or values 7 papers
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[ref]–[ref] and [ref]–[ref]) and the current best determination of ($0.253±0.003$; [ref] ), in addition to the Planck+WP+highL[We used the base cosmology set with and added as free parameters (see Section 6.4.5 of [ref] ).] constraint on and the precise determination of reported here, we derive a $2σ$ upper limit on the neutrino degeneracy parameter, $|ξ|≤0.064$, based on the approach by [ref] .
Precision measures of the primordial abundance of deuterium · Deuterium and the Lepton Asymmetry · 0.88
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On the observational side, to set constraints on the variations we have used the abundances of deuterium [ref] , helium [ref] and lithium [ref] , including also the already mentioned measurements below Spite's plateau.
The cosmological lithium problem, varying constants and the $H_0$ tension · Formalism · 1.00
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After the addition of the most recent measurements of deuterium [ref] and helium [ref] , and using the theoretically derived fitting functions of Ref. [ref] , we find $∑m_ν< 0.24$ eV and $=3.25_-0.24^+0.25$ at $95%$ CL from the analysis of CMB data, WiggleZ power spectrum measurements and the HST $H_0$ prior finding no evidence for $>3$.
Relic Neutrinos, thermal axions and cosmology in early 2014 · Conclusions · 0.91
Compares with it 1 paper
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Note that this constraint is slightly more conservative than the recently suggested $Y_p=0.254±0.003$ [ref] (actually it corresponds to a 99% C.L. exclusion).
Dark Radiation constraints on minicharged particles in models with a hidden photon · Constraints from big bang nucleosynthesis · 0.92
Cites it as background 1 paper
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Following improvements in the He i emissivity calculations (Porter et al. 2012, 2013), there have been two recent reassessments of $Y_P$, by [ref] and by [ref] respectively.
Precision measures of the primordial abundance of deuterium · Combined CMB+BBN Measure of $N_eff$ and · 0.91
What it cites · 2 sentences without a confident label
Compares with 1 paper
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Our baryon mass density $Ω_b h^2$ = 0.0234$±$0.0019 (68% CL) (Fig. [ref]) agrees with the values of 0.0222$±$0.0004 [ref] and 0.0221$±$0.0003 [ref] from fluctuation studies of the CMB radiation.
Planck 2013 results. XVI. Cosmological parameters · Cosmological implications · 0.98
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