Improving Helium Abundance Determinations with Leo P as a Case Study

Aver, Erik; Berg, Danielle A.; Olive, Keith A.; Pogge, Richard W.; Salzer, John J.; Skillman, Evan D.

doi:10.48550/arxiv.2010.04180

Cited by 7 publications

(24 citation statements)

References 89 publications

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“…We note that the CP11 model yields a total He/H abundance instead of a He + /H + one. Nevertheless, it is expected that the difference between the singly ionized helium and total abundances is of the order of 0.008 dex, see Izotov et al (1997); Peimbert et al (2000Peimbert et al ( , 2012; Valerdi et al (2019Valerdi et al ( , 2021; Aver et al (2020). It is known that MW-like galaxies grow from the inside-out following a sequence of SFHs (Star Formation Histories) and ChEHs (CHemical Evolution Histories) at each radii which shape is similar to that galaxies of different masses (Sánchez 2020;Sánchez et al 2020).…”

Section: Discussionmentioning

confidence: 99%

“…Like in the previous explorations Aver et al (2020) were interested in the study of the primordial helium. They studied 16 low-metallicity extragalactic H II regions to lower limit the systematic uncertainties in helium abundance determinations.…”

Section: Compilation Of Helium Abundances In H II Regionsmentioning

confidence: 99%

“…The helium abundance is frequently derived using several emission lines in the optical and NIR wavelength ranges (e.g Izotov et al 1997;Deharveng et al 2000;Peimbert et al 2005;Izotov et al 2014;Valerdi et al 2019Valerdi et al , 2021Aver et al 2020). As mentioned before, many of these studies were used to determine the primordial helium abundance and therefore was important to compute the helium abundance in all their ionic stages and correct for the neutral component (see Sec.…”

Section: Helium Abundances He + /H + In the Literaturementioning

confidence: 99%

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An Empirical Calibration of the Helium Abundance in HII Regions based in Literature and CALIFA Survey data

Valerdi,

Barrera-Ballesteros,

Sánchez

et al. 2021

Preprint

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Helium is the second most common chemical species in the Universe. The study of helium abundance has the potential to unravel the chemical evolution of and within galaxies. In this study, we provide an empirical calibration for the singly ionized helium abundance: 12 + log 10 (He + /H + ), based on the emission line flux ratio He 𝜆5876 /H𝛼 from Galactic and extragalactic H II regions compiled from the literature. Based on this calibrator, we explore for the first time the helium abundance in a large sample of H II regions located in galaxies representative of the nearby Universe from the CALIFA survey. Furthermore, this calibrator allows us to explore the variations of the helium abundance with respect to the oxygen abundance. The observed trends are in agreement with a change in the chemical enrichment with mass/oxygen abundance similar to the one observed due to the inside-out model in a MW-galaxy (highlighting the connection between resolved and global trends in galaxies). Our calibrator provides an empirical proxy to estimate the helium abundance at kpc scales as well as to constrain chemical evolutionary models.

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Section: Discussionmentioning

confidence: 99%

Section: Compilation Of Helium Abundances In H II Regionsmentioning

confidence: 99%

Section: Helium Abundances He + /H + In the Literaturementioning

confidence: 99%

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An Empirical Calibration of the Helium Abundance in HII Regions based in Literature and CALIFA Survey data

Valerdi,

Barrera-Ballesteros,

Sánchez

et al. 2021

Preprint

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“…These values were taken from synthetic stellar libraries such as those from ; . In the updated analysis by Aver et al (2020), the authors quantified the hydrogen and helium line absorptions from the BPASS library (see Stanway & Eldridge 2018, and references therein). They proposed that this uniform ion absorption should be corrected by a relative scaling factor for each transition.…”

Section: Analysis Of the Synthesis Spectral Continuum Fittingmentioning

confidence: 99%

New insights on the nebular emission, ionizing radiation and low metallicity of Green Peas from advanced modelling

Fernández,

Amorín,

Pérez-Montero

et al. 2021

Preprint

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Low-metallicity, compact starburst galaxies referred to as Green Peas (GPs) provide a unique window to study galactic evolution across cosmic epochs. In this work, we present new deep optical spectra for three GPs from OSIRIS at the 10m Gran Telescopio Canarias (GTC), which are studied using a state-of-the-art methodology. A stellar population synthesis is conducted with 1098 spectral templates. The methodology succeeds at characterising stellar populations from 0.5 Myrs to 10 Gyrs. The light distribution shows a large red excess from a single population with 𝑙𝑜𝑔 (𝑎𝑔𝑒) > 8.5𝑦𝑟 in the GP sample analysed. This points towards an incomplete characterisation of the gas luminosity, whose continuum already accounts between 7.4% and 27.6% in the galaxy sample. The emission spectra are fitted with the largest Bayesian chemical model consisting of a electron temperature, a electron density, the logarithmic extinction coefficient and eleven ionic species under the direct method paradigm. Additionally, building on previous work, we propose a neural networks sampler to constrain the effective temperature and ionization parameter of each source from photoionization model grids. Finally, we combine both methodologies into a 16-dimensional model, which for the first time, simultaneously explores the direct method and photoionization parameter spaces. Both techniques consistently indicate a low metallicity gas, 7.76 < 12 + 𝑙𝑜𝑔 ( 𝑂 /𝐻) < 8.04, ionized by strong radiation fields, in agreement with previous works.

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“…Other recent determinations of the primordial helium abundances using H II regions have been done by Izotov et al (2014); Aver et al (2015); Peimbert et al (2016); Valerdi et al (2019);Fernández et al (2019); Aver et al (2020); Hsyu et al (2020); Kurichin et al (2021).…”

Section: Introductionmentioning

confidence: 99%

Chemical abundances in 7 metal-poor HII regions and a determination of the primordial helium abundance

Valerdi,

Peimbert,

Peimbert

2021

Preprint

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We conducted a long-slit spectrophotometry analysis to obtain the chemical abundances of seven metal-poor H II regions in three galaxies: UM 160, UM 420, and TOL 0513−393. The data have been taken with the Focal Reducer Low Dispersion Spectrograph 1 (FORS1) at the 8.2-m Very Large Telescope. We derived the physical conditions and the chemical abundances of N, O, Ne, S, Ar and Cl. We also performed a detailed analysis that involves abundance determinations using the 𝑡 2 formalism. Based on He I recombination line intensity ratios, together with the Helio14 code, we derived the abundance of He. In addition, for a value Δ𝑌 /Δ𝑍 𝑂 = 3.3 ± 0.7, we have estimated that the primordial helium abundance by mass is 𝑌 P = 0.2448 ± 0.0033. This value agrees with values derived from Standard Big Bang Nucleosynthesis and with other recent determinations of 𝑌 P .

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Improving Helium Abundance Determinations with Leo P as a Case Study

Cited by 7 publications

References 89 publications

An Empirical Calibration of the Helium Abundance in HII Regions based in Literature and CALIFA Survey data

An Empirical Calibration of the Helium Abundance in HII Regions based in Literature and CALIFA Survey data

New insights on the nebular emission, ionizing radiation and low metallicity of Green Peas from advanced modelling

Chemical abundances in 7 metal-poor HII regions and a determination of the primordial helium abundance

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