Implications of inhomogeneous metal mixing for stellar archaeology

Tarumi, Yuta; Hartwig, Tilman; Magg, Mattis

doi:10.48550/arxiv.2005.10401

Cited by 4 publications

(7 citation statements)

References 113 publications

(152 reference statements)

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“…Subsequently, it has become common practice to use SN models to infer the properties of the primordial progenitors of the most metal-poor observed stars, both for individual stars (e.g., Heger & Woosley 2010;Hansen et al 2011;Nomoto et al 2013;Ishigaki et al 2014;Bessell et al 2015;Placco et al 2016) and for large samples (Cayrel et al 2004;Fraser et al 2017;Ishigaki et al 2018). Additionally, constraints on the primordial IMF can be inferred from bulk properties of metal-poor stars with semi-analytical models (de Bennassuti et al 2017;Hartwig et al 2018;Tarumi et al 2020a). For these purposes, libraries of SN yields have been computed (Heger & Woosley 2010;Nomoto et al 2013;Ishigaki et al 2018).…”

Section: Introductionmentioning

confidence: 99%

A Minimum Dilution Scenario for Supernovae and Consequences for Extremely Metal-Poor Stars

Magg,

Nordlander,

Glover

et al. 2020

Preprint

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To date no metal-free stars have been identified by direct observations. The most common method of constraining their properties is searching the spectra of the most metal-poor stars for the chemical elements created in the first stars and their supernova. In this approach, modelled supernova yields are compared to the observed abundance patterns in extremely metal-poor stars. The method typically only uses the abundance ratios, i.e., the yields are diluted to the observed level. Following the usual assumption of spherical symmetry we compute a simple lower limit of the mass a supernova can mix with and find that it is consistent with all published simulations of early chemical enrichment in the interstellar medium. For three different cases, we demonstrate that this dilution limit can change the conclusions from the abundance fitting. There is a large discrepancy between the dilution found in simulations of SN explosions in minihaloes and the dilution assumed in many abundance fits. Limiting the dilution can significantly alter the likelihood of which supernovae are possible progenitors of observed CEMP-no stars. In particular, some of the faint, very low-yield SNe, which have been suggested as models for the abundance pattern of SMSS0313-6708, cannot explain the measured metal abundances, as their predicted metal yields are too small by two orders of magnitude. Altogether, the new dilution model presented here emphasizes the need to better understand the mixing and dilution behaviour of aspherical SNe.

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Section: Introductionmentioning

confidence: 99%

A Minimum Dilution Scenario for Supernovae and Consequences for Extremely Metal-Poor Stars

Magg,

Nordlander,

Glover

et al. 2020

Preprint

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“…These stars, however, may retain a representative enrichment pattern of multiple Pop III CCSNe occurred within a small host halo. For the metal-poor OHS subgroup with [Fe/H]< −1.5, a stochastic chemical enrichment in the early Universe coupled with highly inhomogeneous nature of SN metal ejecta would not completely rule out the Pop III CCSNe enrichment (Ritter et al 2012;Salvadori et al 2015;Tarumi et al 2020). By taking into account this scenario, we examine whether the observed patterns of abundance ratios ([X/Fe]) can accept or rule-out the Pop III CCSNe enrichment.…”

Section: Chemical Enrichment Scenariosmentioning

confidence: 99%

“…It has been proposed that various different mechanisms could have played a role in determining the condition at which the first metal-enriched stars form, potentially leading to the [Fe/H] spread. They includes (1) the properties of the Pop III stellar systems such as the IMF, multiplicity, and the number of Pop III stars per mini halos (Clark et al 2011;Greif et al 2011;Stacy & Bromm 2014;Susa et al 2014;Hartwig et al 2018), (2) hydrodynamical properties of Pop III SN ejecta that could depend on the explosion energy and geometry (Joggerst et al 2009;Tominaga 2009;Ritter et al 2012), (3) the properties of the interstellar medium to which energy and metals from Pop III SNe are injected (Kitayama & Yoshida 2005;Greif et al 2010;Jeon et al 2014;Chiaki et al 2018;Tarumi et al 2020), (4) metals and dust abundances that determine the efficiency of the formation of the next-generation low-mass stars (e.g., Omukai et al 2005;Chiaki et al 2014;de Bennassuti et al 2014;) and ( 5) the redshift evolution of CMB and the properties of the host halos (Tumlinson 2007;Smith et al 2009). Predictions on their combined effects on the [Fe/H] spread among the first metal-enriched stars would provide useful insights into the best strategy for the upcoming Galactic Archaeology surveys.…”

Section: Best-fit Pop III Ccsn Model Parametersmentioning

confidence: 99%

“…In addition to the Pop III properties, it remains unclear how the ejected metals from Pop III supernovae are transported in the inter galactic medium (IGM) and mixed with primordial gas, from which the next generation, namely, the first metal-enriched stars formed (e.g., Smith et al 2009;Ritter et al 2012;Chiaki et al 2018;Tarumi et al 2020). Such mechanisms can depend on multiplicity of Pop III stars (Hartwig et al 2018 or presence of radiative feedback from the Pop III stars (Greif et al 2010;Jeon et al 2014;Cooke & Madau 2014;Chiaki et al 2018).…”

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confidence: 99%

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Origin of metals in old Milky Way halo stars based on GALAH and Gaia

Ishigaki,

Hartwig,

Tarumi

et al. 2021

Preprint

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Stellar and supernova nucleosynthesis in the first few billion years of the cosmic history have set the scene for early structure formation in the Universe, while little is known about their nature. Making use of stellar physical parameters measured by GALAH Data Release 3 with accurate astrometry from the Gaia EDR3, we have selected ∼ 100 old main-sequence turn-off stars (ages 12 Gyrs) with kinematics compatible with the Milky Way stellar halo population in the Solar neighborhood. Detailed homogeneous elemental abundance estimates by GALAH DR3 are compared with supernova yield models of Pop III (zero-metal) corecollapse supernovae (CCSNe), normal (non-zero-metal) CCSNe, and Type Ia supernovae (SN Ia) to examine which of the individual yields or their combinations best reproduce the observed elemental abundance patterns for each of the old halo stars ("OHS"). We find that the observed abundances in the OHS with [Fe/H]> −1.5 are best explained by contributions from both CCSNe and SN Ia, where the fraction of SN Ia among all the metal-enriching SNe is up to 10-20 % for stars with high [Mg/Fe] ratios and up to 20-27 % for stars with low [Mg/Fe] ratios, depending on the assumption about the relative fraction of near-Chandrasekhar-mass SNe Ia progenitors. The results suggest that, in the progenitor systems of the OHS with [Fe/H]> −1.5, ∼ 50-60% of Fe mass originated from normal CCSNe at the earliest phases of the Milky Way formation. These results provide an insight into the birth environments of the oldest stars in the Galactic halo.

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“…Stacy & Bromm 2013;Susa et al 2014;Hirano et al 2015;Machida & Nakamura 2015;Stacy et al 2016;Sugimura et al 2020), and indirect observational constraints (e.g. Frebel & Norris 2015;Ji et al 2015;Hartwig et al 2015;Magg et al 2019;Ishigaki et al 2018;Tarumi et al 2020) converge on the picture that Pop III stars are characterized by a topheavy initial mass function (IMF), covering a few to a few hundred M . As a result, they have distinct features compared with present-day stars formed in metal-enriched enrionments, such as bluer spectra with narrow He ii emission lines and higher efficiencies of producing supernovae (SNe) E-mail: boyuan@utexas.edu and (binary) black holes (e.g.…”

Section: Introductionmentioning

confidence: 97%

When did Population III star formation end?

Liu,

Bromm

2020

Preprint

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We construct a theoretical framework to study Population III (Pop III) star formation in the post-reionization epoch (z 6) by combining cosmological simulation data with semi-analytical models. We find that due to radiative feedback (i.e. Lyman-Werner and ionizing radiation) massive haloes (M halo 10 9 M ) are the major ( 90%) hosts for potential Pop III star formation at z 6, where dense pockets of metal-poor gas may survive to form Pop III stars, under inefficient mixing of metals released by supernovae. Metal mixing is the key process that determines not only when Pop III star formation ends, but also the total mass, M PopIII , of active Pop III stars per host halo, which is a crucial parameter for direct detection and identification of Pop III hosts. Both aspects are still uncertain due to our limited knowledge of metal mixing during structure formation. Current predictions range from early termination at the end of reionization (z ∼ 5) to continuous Pop III star formation extended to z = 0 at a non-negligible rate ∼ 10 −7 M yr −1 Mpc −3 , with M PopIII ∼ 10 3 − 10 6 M . This leads to a broad range of redshift limits for direct detection of Pop III hosts, z PopIII ∼ 0.5 − 12.5, with detection rates 0.1−20 arcmin −2 , for current and future space telescopes (e.g. HST, WFIRST and JWST). Our model also predicts that the majority ( 90%) of the cosmic volume is occupied by metal-free gas. Measuring the volume filling fractions of this metal-free phase can constrain metal mixing parameters and Pop III star formation.

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Implications of inhomogeneous metal mixing for stellar archaeology

Cited by 4 publications

References 113 publications

A Minimum Dilution Scenario for Supernovae and Consequences for Extremely Metal-Poor Stars

A Minimum Dilution Scenario for Supernovae and Consequences for Extremely Metal-Poor Stars

Origin of metals in old Milky Way halo stars based on GALAH and Gaia

When did Population III star formation end?

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