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

Ishigaki, Miho N.; Hartwig, Tilman; Tarumi, Yuta; Leung, Shing-Chi; Tominaga, Nozomu; Magg, Mattis; Simionescu, A.; Nomoto, Ken’ichi

doi:10.1093/mnras/stab1982

Cited by 16 publications

(17 citation statements)

References 195 publications

(266 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Our improved treatment of metallicity allowed us to model the transition from Pop III to Pop II star formation more realistically, and we have implemented a new model for inhomogeneous metal mixing in the first galaxies (Hartwig et al 2018b;Tarumi et al 2020;Ishigaki et al 2021). This allows us to predict the properties of second-generation and extremely metal-poor (EMP) stars.…”

Section: A-sloth Ancestorsmentioning

confidence: 99%

“…For example, the formation of the first stars in the universe (Population III or Pop III) is not well understood. However, it affects the epoch of reionization (Bromm & Yoshida 2011;Dayal & Ferrara 2018), the formation of the first supermassive black holes (SMBHs; Latif & Ferrara 2016;Woods et al 2019;Inayoshi et al 2020), and the population of old and metal-poor stars in the MW and its satellites (Frebel & Norris 2015;Ishigaki et al 2021). An SAM allows us to model the formation of the first stars under different assumptions (e.g., regarding their mass distribution or star formation efficiency (SFE)) and determine which assumption agrees best with observations, and the models that reproduce successfully known observables can be used to predict new diagnostics.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Public Release of A-SLOTH: Ancient Stars and Local Observables by Tracing Halos

Hartwig

Magg

Chen

et al. 2022

ApJ

Self Cite

View full text Add to dashboard Cite

The semianalytical model a-sloth (Ancient Stars and Local Observables by Tracing Halos) is the first public code that connects the formation of the first stars and galaxies to observables. After several successful projects with this model, we publish the source code (https://gitlab.com/thartwig/asloth) and describe the public version in this paper. The model is based on dark matter merger trees that can either be generated based on Extended Press–Schechter theory or be imported from dark matter simulations. On top of these merger trees, a-sloth applies analytical recipes for baryonic physics to model the formation of both metal-free and metal-poor stars and the transition between them with unprecedented precision and fidelity. a-sloth samples individual stars and includes radiative, chemical, and mechanical feedback. It is calibrated based on six observables, such as the optical depth to Thomson scattering, the stellar mass of the Milky Way and its satellite galaxies, the number of extremely metal-poor stars, and the cosmic star formation rate density at high redshift. a-sloth has versatile applications with moderate computational requirements. It can be used to constrain the properties of the first stars and high-z galaxies based on local observables, predicts properties of the oldest and most metal-poor stars in the Milky Way, can serve as a subgrid model for larger cosmological simulations, and predicts next-generation observables of the early universe, such as supernova rates or gravitational wave events.

show abstract

Section: A-sloth Ancestorsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Public Release of A-SLOTH: Ancient Stars and Local Observables by Tracing Halos

Hartwig

Magg

Chen

et al. 2022

ApJ

Self Cite

View full text Add to dashboard Cite

show abstract

“…We expect great progress here and an iterative convergence on deciphering the origin of the elements, as elemental abundance measurements -especially of environments different than the already well-studied disc -inform the constraints on chemical enrichment processes and yields (e.g. Fernández-Alvar et al 2018;Vincenzo et al 2019;Eitner et al 2020;Ishigaki et al 2021;Sanders et al 2021)…”

Section: O U T L O O Kmentioning

confidence: 99%

The GALAH Survey: chemical tagging and chrono-chemodynamics of accreted halo stars with GALAH+ DR3 andGaiaeDR3

Buder

Lind

Ness

et al. 2021

Monthly Notices of the Royal Astronomical Society

Self Cite

View full text Add to dashboard Cite

Since the advent of Gaia astrometry, it is possible to identify massive accreted systems within the Galaxy through their unique dynamical signatures. One such system, Gaia-Sausage-Enceladus (GSE), appears to be an early “building block” given its virial mass >1010 M⊙ at infall (z ∼ 1 − 3). In order to separate the progenitor population from the background stars, we investigate its chemical properties with up to 30 element abundances from the GALAH+ Survey Data Release 3 (DR3). To inform our choice of elements for purely chemically selecting accreted stars, we analyse 4164 stars with low-α abundances and halo kinematics. These are most different to the Milky Way stars for abundances of Mg, Si, Na, Al, Mn, Fe, Ni, and Cu. Based on the significance of abundance differences and detection rates, we apply Gaussian mixture models to various element abundance combinations. We find the most populated and least contaminated component, which we confirm to represent GSE, contains 1049 stars selected via [Na/Fe] vs. [Mg/Mn] in GALAH+ DR3. We provide tables of our selections and report the chrono-chemodynamical properties (age, chemistry, and dynamics). Through a previously reported clean dynamical selection of GSE stars, including $30 < \sqrt{J_R / \, \mathrm{kpc\, km\, s^{-1}}} < 55$, we can characterise an unprecedented 24 abundances of this structure with GALAH+ DR3. With our chemical selection we characterise the dynamical properties of the GSE, for example mean $\sqrt{J_R / \, \mathrm{kpc\, km\, s^{-1}}} = 26^{+9}_ {-14}$. We find only $(29\pm 1)\%$ of the GSE stars within the clean dynamical selection region. Our methodology will improve future studies of accreted structures and their importance for the formation of the Milky Way.

show abstract

“…We expect great progress here and an iterative convergence on deciphering the origin of the elements, as elemental abundance measurements -especially of environments different than the already well-studied disk -inform the constraints on chemical enrichment processes and yields (e.g. Fernández-Alvar et al 2018;Vincenzo et al 2019;Eitner et al 2020;Sanders et al 2021;Ishigaki et al 2021).…”

Section: Discussionmentioning

confidence: 99%

The GALAH Survey: Chemical tagging and chrono-chemodynamics of accreted halo stars with GALAH+ DR3 and $Gaia$ eDR3

Buder,

Lind,

Ness

et al. 2021

Preprint

Self Cite

View full text Add to dashboard Cite

Since the advent of Gaia astrometry, it is possible to identify massive accreted systems within the Galaxy through their unique dynamical signatures. One such system, Gaia-Sausage-Enceladus (GSE), appears to be an early "building block" given its virial mass > 10 10 M at infall (𝑧 ∼ 1 − 3). In order to separate the progenitor population from the background stars, we investigate its chemical properties with up to 30 element abundances from the GALAH+ Survey Data Release 3 (DR3). To inform our choice of elements for purely chemically selecting accreted stars, we analyse 4164 stars with low-𝛼 abundances and halo kinematics. These are most different to the Milky Way stars for abundances of Mg, Si, Na, Al, Mn, Fe, Ni, and Cu. Based on the significance of abundance differences and detection rates, we apply Gaussian mixture models to various element abundance combinations. We find the most populated and least contaminated component, which we confirm to represent GSE, contains 1049 stars selected via [Na/Fe] vs. [Mg/Mn] in GALAH+ DR3. We provide tables of our selections and report the chrono-chemodynamical properties (age, chemistry, and dynamics). Through a previously reported clean dynamical selection of GSE stars, including 30 < √︁ 𝐽 𝑅 / kpc km s −1 < 55, we can characterise an unprecedented 24 abundances of this structure with GALAH+ DR3. Our chemical selection allows us to prevent circular reasoning and characterise the dynamical properties of the GSE, for example mean √︁ 𝐽 𝑅 / kpc km s −1 = 26 +9 −14 . We find only (29 ± 1)% of the GSE stars within the clean dynamical selection region. We thus discuss chemodynamic selections (such as eccentricity and upper limits on [Na/Fe]).

show abstract

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

Cited by 16 publications

References 195 publications

Public Release of A-SLOTH: Ancient Stars and Local Observables by Tracing Halos

Public Release of A-SLOTH: Ancient Stars and Local Observables by Tracing Halos

The GALAH Survey: chemical tagging and chrono-chemodynamics of accreted halo stars with GALAH+ DR3 andGaiaeDR3

The GALAH Survey: Chemical tagging and chrono-chemodynamics of accreted halo stars with GALAH+ DR3 and $Gaia$ eDR3

Contact Info

Product

Resources

About