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Main Authors: Alarcon, Alex, Hearin, Andrew P., Becker, Matthew R., Beltz-Mohrmann, Gillian, Benson, Andrew, Weerasooriya, Sachi
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2510.27604
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author Alarcon, Alex
Hearin, Andrew P.
Becker, Matthew R.
Beltz-Mohrmann, Gillian
Benson, Andrew
Weerasooriya, Sachi
author_facet Alarcon, Alex
Hearin, Andrew P.
Becker, Matthew R.
Beltz-Mohrmann, Gillian
Benson, Andrew
Weerasooriya, Sachi
contents We present DiffstarPop, a differentiable forward model of cosmological populations of galaxy star formation histories (SFH). In the model, individual galaxy SFH is parametrized by Diffstar, which has parameters $θ_{\rm SFH}$ that have a direct interpretation in terms of galaxy formation physics, such as star formation efficiency and quenching. DiffstarPop is a model for the statistical connection between $θ_{\rm SFH}$ and the mass assembly history (MAH) of dark matter halos. We have formulated DiffstarPop to have the minimal flexibility needed to accurately reproduce the statistical distributions of galaxy SFH predicted by a diverse range of simulations, including the IllustrisTNG hydrodynamical simulation, the Galacticus semi-analytic model, and the UniverseMachine semi-empirical model. Our publicly available code written in JAX includes Monte Carlo generators that supply statistical samples of galaxy assembly histories that mimic the populations seen in each simulation, and can generate SFHs for $10^6$ galaxies in 1.1 CPU-seconds, or 0.03 GPU-seconds. We conclude the paper with a discussion of applications of DiffstarPop, which we are using to generate catalogs of synthetic galaxies populating the merger trees in cosmological N-body simulations.
format Preprint
id arxiv_https___arxiv_org_abs_2510_27604
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle DiffstarPop: A generative physical model of galaxy star formation history
Alarcon, Alex
Hearin, Andrew P.
Becker, Matthew R.
Beltz-Mohrmann, Gillian
Benson, Andrew
Weerasooriya, Sachi
Astrophysics of Galaxies
Cosmology and Nongalactic Astrophysics
We present DiffstarPop, a differentiable forward model of cosmological populations of galaxy star formation histories (SFH). In the model, individual galaxy SFH is parametrized by Diffstar, which has parameters $θ_{\rm SFH}$ that have a direct interpretation in terms of galaxy formation physics, such as star formation efficiency and quenching. DiffstarPop is a model for the statistical connection between $θ_{\rm SFH}$ and the mass assembly history (MAH) of dark matter halos. We have formulated DiffstarPop to have the minimal flexibility needed to accurately reproduce the statistical distributions of galaxy SFH predicted by a diverse range of simulations, including the IllustrisTNG hydrodynamical simulation, the Galacticus semi-analytic model, and the UniverseMachine semi-empirical model. Our publicly available code written in JAX includes Monte Carlo generators that supply statistical samples of galaxy assembly histories that mimic the populations seen in each simulation, and can generate SFHs for $10^6$ galaxies in 1.1 CPU-seconds, or 0.03 GPU-seconds. We conclude the paper with a discussion of applications of DiffstarPop, which we are using to generate catalogs of synthetic galaxies populating the merger trees in cosmological N-body simulations.
title DiffstarPop: A generative physical model of galaxy star formation history
topic Astrophysics of Galaxies
Cosmology and Nongalactic Astrophysics
url https://arxiv.org/abs/2510.27604