A bound on the 12C/13C ratio in near-pristine gas with ESPRESSO

Welsh, Louise; Cooke, Ryan; Fumagalli, Michele

doi:10.1093/mnras/staa807

Cited by 28 publications

(29 citation statements)

References 90 publications

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“…In this paper, we use a novel approach to analyse the chemistry of the most metal-poor stars, and use this tool to infer the number of massive Population III stars that have enriched the surviving metalpoor stellar relics. Previously, we have applied this tool to investigate the enrichment of the most metal-poor damped Lyman α systems (DLAs; Welsh, Cooke & Fumagalli 2019;Welsh et al 2020). We now extend this work to investigate the stochastic enrichment of a sample of metal-poor Milky Way halo stars using their measured [Mg/Ca] and [Ni/Fe] abundances.…”

Section: Introductionmentioning

confidence: 91%

“…These simulations calculated the SNe yields for discrete combinations of M, E exp , and f He ; we linearly interpolate over this 3D parameter space for our analysis. Similar to the approach from Welsh et al (2019Welsh et al ( , 2020, we begin our analysis with 400 randomly initialized walkers. These walkers each take 10 000 steps to converge on the stable posterior distributions shown in Fig.…”

Section: Likelihood Analysismentioning

confidence: 99%

“…We can therefore determine the elemental abundances of these systems with a high degree of precision (∼ 0.01 dex; Wolfe, Gawiser & Prochaska 2005). Additionally, when investigating these systems (as done in Welsh et al 2019Welsh et al , 2020, we can utilize the abundance ratios of the most abundant chemical elements, including [C/O]. The simulated [C/O] HW10 yields share an almost monotonically decreasing relationship with progenitor star mass.…”

Section: Comparison With Dlasmentioning

confidence: 99%

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The stochastic enrichment of Population II stars

Welsh

Cooke

Fumagalli

2020

Monthly Notices of the Royal Astronomical Society

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We investigate the intrinsic scatter in the chemical abundances of a sample of metal-poor ([Fe/H] <−2.5) Milky Way halo stars. We draw our sample from four historic surveys and focus our attention on the stellar Mg, Ca, Ni, and Fe abundances. Using these elements, we investigate the chemical enrichment of these metal-poor stars using a model of stochastic chemical enrichment. Assuming that these stars have been enriched by the first generation of massive metal-free stars, we consider the mass distribution of the enriching population alongside the stellar mixing and explosion energy of their supernovae. For our choice of stellar yields, our model suggests that the most metal-poor stars were enriched, on average, by $\hat{N}_{\star }=5^{+13}_{-3}~(1\sigma )$ Population III stars. This is comparable to the number of enriching stars inferred for the most metal-poor DLAs. Our analysis therefore suggests that some of the lowest mass structures at z ∼ 3 contain the chemical products from <13 (2σ) Population III enriched minihaloes. The inferred IMF is consistent with that of a Salpeter distribution and there is a preference towards ejecta from minimally mixed hypernovae. However, the estimated enrichment model is sensitive to small changes in the stellar sample. An offset of ∼0.1 dex in the [Mg/Ca] abundance is shown to be sensitive to the inferred number of enriching stars. We suggest that this method has the potential to constrain the multiplicity of the first generation of stars, but this will require: (1) a stellar sample whose systematic errors are well understood; and, (2) documented uncertainties associated with nucleosynthetic yields.

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Section: Introductionmentioning

confidence: 91%

Section: Likelihood Analysismentioning

confidence: 99%

Section: Comparison With Dlasmentioning

confidence: 99%

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The stochastic enrichment of Population II stars

Welsh

Cooke

Fumagalli

2020

Monthly Notices of the Royal Astronomical Society

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“…More importantly, it is believed that a subset of these objects are indeed "true" second-generation stars, also known as extremely metal-poor (EMP; [Fe/H] 18 <−3.0) stars (Beers & Christlieb 2005). The chemical abundance patterns of these EMP stars can place direct constraints on the nature of the first (Population III) stars to be formed in the universe (e.g., Christlieb et al 2002;Frebel et al 2006Norris et al 2007;Caffau et al 2011Caffau et al , 2016Ito et al 2013;Hansen et al 2014;Keller et al 2014;Placco et al 2014aPlacco et al , 2016bStarkenburg et al 2014Starkenburg et al , 2018Meléndez et al 2016;Roederer et al 2016;Aguado et al 2018;Ezzeddine et al 2019;Mardini et al 2019aMardini et al , 2019b and possible astrophysical site(s) for their occurrence, such as dwarf galaxies (Salvadori et al 2015;Hansen et al 2017;Longeard et al 2018;Nagasawa et al 2018;Marshall et al 2019) and damped Lyα systems (Cooke et al 2011;Cooke & Madau 2014;Welsh et al 2020).…”

Section: Introductionmentioning

confidence: 99%

The R-process Alliance: The Peculiar Chemical Abundance Pattern of RAVE J183013.5−455510*

Placco

Santucci

Yuan

et al. 2020

ApJ

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We report on the spectroscopic analysis of RAVE J183013.5−455510, an extremely metal-poor star, highly enhanced in CNO, and with discernible contributions from the rapid neutron-capture process. There is no evidence of binarity for this object. At [ ] Fe H =−3.57, this star has one of the lowest metallicities currently observed, with 18 measured abundances of neutron-capture elements. The presence of Ba, La, and Ce abundances above the solar system r-process predictions suggests that there must have been a non-standard source of r-process elements operating at such low metallicities. One plausible explanation is that this enhancement originates from material ejected at unusually high velocities in a neutron star merger event. We also explore the possibility that the neutroncapture elements were produced during the evolution and explosion of a rotating massive star. In addition, based on comparisons with yields from zero-metallicity faint supernova, we speculate that RAVE J1830−4555 was formed from a gas cloud pre-enriched by both progenitor types. From analysis based on Gaia DR2 measurements, we show that this star has orbital properties similar to the Galactic metal-weak thick-disk stellar population.

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“…Apparent strong enhancement of heavy Mg isotopes previously reported in the literature for these systems were hence likely due to distortion in the UVES wavelength scale. This also shows that ESPRESSO is well suited for such isotopic measurements in various absorption systems, opening up a new way to place constraints on the stellar nucleosynthetic history over cosmic time (see also Welsh et al 2020).…”

Section: Discussionmentioning

confidence: 77%

Sharpening quasar absorption lines with ESPRESSO. Temperature of warm gas at z ~ 2, constraints on the Mg isotopic ratio, and structure of cold gas at z ~ 0.5

Noterdaeme

Balashev

Ledoux

et al. 2021

A&A

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Aims. We aim to study several key physical properties of quasar absorption-line systems that are subtly encoded in their absorption profiles and have not yet been thoroughly investigated or constrained. Methods. We analysed a high-resolution (R = 140 000) spectrum of the bright quasar HE 0001−2340 (zem = 2.26) obtained with ESPRESSO, which was recently installed at the Very Large Telescope. We analysed three systems at z = 0.45, z = 1.65, and z = 2.19 using multiple-component Voigt-profile fitting. We also compared our spectrum with those obtained with VLT/UVES, covering a total period of 17 years. Results. We disentangle turbulent and thermal broadening in many components spread over about 400 km s−1 in the z ≈ 2.19 sub-damped Lyman-α system. We derive an average temperature of 16 000 ± 1300 K, which is about twice the canonical value of the warm neutral medium in the Galactic interstellar medium (ISM). A comparison with other high-z, low-metallicity absorbers reveals an anti-correlation between gas temperature and total H I column density. Although requiring confirmation, this could be the first observational evidence of a thermal decrease with galactocentric distance; in other words, we may be witnessing a thermal transition between the circumgalactic medium and the cooler ISM. We revisit the Mg isotopic ratios at z = 0.45 and z = 1.65 and constrain them to be ξ = (26Mg + 25Mg)/24Mg < 0.6 and < 1.4 in these two systems, respectively. These values are consistent with the standard solar ratio; that is, we do not confirm strong enhancement of heavy isotopes previously inferred from UVES data. Finally, we confirm the partial coverage of the quasar emission-line region by a Fe I-bearing cloud in the z = 0.45 system and present evidence for velocity substructure of the gas that has Doppler parameters of the order of only ∼0.3 km s−1. This agrees well with the low kinetic temperature of T ∼ 100 K inferred from modelling of the gas physical conditions. Conslusions. This work demonstrates the unique insight provided by high-fidelity, high-resolution optical spectrographs on large telescopes when used to investigate the thermal state of the gas in and around galaxies as well as its spatial and velocity structure on small scales, and to constrain the associated stellar nucleosynthetic history.

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A bound on the 12C/13C ratio in near-pristine gas with ESPRESSO

Cited by 28 publications

References 90 publications

The stochastic enrichment of Population II stars

The stochastic enrichment of Population II stars

The R-process Alliance: The Peculiar Chemical Abundance Pattern of RAVE J183013.5−455510*

Sharpening quasar absorption lines with ESPRESSO. Temperature of warm gas at z ~ 2, constraints on the Mg isotopic ratio, and structure of cold gas at z ~ 0.5

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