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

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.

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“…Other SAMs do not comment on their runtime efficiency. For more details on the numerical implementation of A-SLOTH, see Magg et al (2022c).…”

Section: Advantages Of A-slothmentioning

confidence: 99%

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

Hartwig

Magg

Chen

et al. 2022

ApJ

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“…We use the semianalytical model A-SLOTH to simulate the formation of the first galaxies (Hartwig et al 2022;Magg et al 2022). The model is based on dark matter merger trees, which are generated with the Extended Press-Schechter formalism (EPS; Press & Schechter 1974;Bond et al 1991).…”

Section: Methodsmentioning

confidence: 99%

Unveiling the Contribution of Population III Stars in Primeval Galaxies at Redshift ≥6

Riaz

Hartwig

Latif

2022

ApJL

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Detection of the first stars has remained elusive so far but their presence may soon be unveiled by upcoming JWST observations. Previous studies have not investigated the entire possible range of halo masses and redshifts that may help in their detection. Motivated by the prospects of detecting galaxies up to z ∼ 20 in the JWST early data release, we quantify the contribution of Population III stars to high-redshift galaxies from 6 ≤ z ≤ 30 by employing the semianalytical model a-sloth, which self-consistently models the formation of Population III and Population II stars along with their feedback. Our results suggest that the contribution of Population III stars is the highest in low-mass halos of 107–109 M ⊙. While high-mass halos ≥1010 M ⊙ contain less than 1% Population III stars, they host galaxies with stellar masses of 109 M ⊙ as early as z ∼ 30. Interestingly, overall the apparent magnitude of Population III stars gets brighter toward higher redshift due to the higher stellar masses, but Population III–dominated galaxies are too faint to be directly detected with JWST. Our results predict JWST can detect galaxies up to z ∼ 30, which may help in constraining the initial mass function of Population III stars and will guide observers to discern the contribution of Population III stars to high-redshift galaxies.

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“…For a discussion of the large-scale impact of LW feedback and the associated uncertainties, we again refer to Section 4.3.2. For completeness, we also plot the estimate for M crit SFRD for Pop III and Pop II stars at z > 5 from different studies, including numerical simulations ( Johnson et al 2013, de Souza et al 2014, Xu et al 2016, Jaacks et al 2018, Sarmento et al 2019, Liu & Bromm 2020b) and semianalytical models (Trenti & Stiavelli 2009, Magg et al 2022a. For comparison, we also provide the observational constraints from Madau & Dickinson (2014), Behroozi & Silk (2015), Finkelstein (2016), and with v st = 0 given by Equation 11, the minimum mass required for the development of a baryonic overdensity computed by Naoz & Barkana (2007), and the critical mass for an atomic cooling halo (taken from Hummel et al 2012 andHartwig et al 2022).…”

Section: Redshiftmentioning

confidence: 99%

The First Stars: Formation, Properties, and Impact

Klessen

Glover

2023

Annual Review of Astronomy and Astrophysics

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The first generation of stars, often called Population III (or Pop III), form from metal-free primordial gas at redshifts z ∼ 30 and below. They dominate the cosmic star-formation history until z ∼ 15–20, at which point the formation of metal-enriched Population II stars takes over. We review current theoretical models for the formation, properties, and impact of Pop III stars and discuss existing and future observational constraints. Key takeaways from this review include the following: ▪ Primordial gas is highly susceptible to fragmentation and Pop III stars form as members of small clusters with a logarithmically flat mass function. ▪ Feedback from massive Pop III stars plays a central role in regulating subsequent star formation, but major uncertainties remain regarding its immediate impact. ▪ In extreme conditions, supermassive Pop III stars can form, reaching masses of several 105 M⊙. Their remnants may be the seeds of the supermassive black holes observed in high-redshift quasars. ▪ Direct observations of Pop III stars in the early Universe remain extremely challenging. Indirect constraints from the global 21-cm signal or gravitational waves are more promising. ▪ Stellar archeological surveys allow us to constrain both the low-mass and the high-mass ends of the Pop III mass distribution. Observations suggest that most massive Pop III stars end their lives as core-collapse supernovae rather than as pair-instability supernovae. Expected final online publication date for the Annual Review of Astronomy and Astrophysics, Volume 61 is August 2023. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

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

Cited by 8 publications

References 15 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

Unveiling the Contribution of Population III Stars in Primeval Galaxies at Redshift ≥6

The First Stars: Formation, Properties, and Impact

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