Learning the Universe with PRFM-vol: Introducing a new subgrid model for star formation in cosmological simulations
Abstract
We introduce PRFM-vol, a new subgrid model for star formation in cosmological simulations that aims to increase the physical realism of cosmological simulations by leveraging results obtained with focused ISM simulations. We deploy a modified effective equation of state and calculate the star formation rate for each gas cell as a function of the ambient densities of gas, dark matter, and stars, based on the pressure-regulated feedback-modulated (PRFM) theory of star formation. Test simulations of our model in isolated galaxies show that we match PRFM predictions and TIGRESS scaling relations remarkably well, provided sufficiently high resolution is available. In particular, we are able to clearly demonstrate the impact of the stellar potential on the star formation rate, thereby retaining an important prediction of PRFM. We then apply our new model to cosmological multizoom simulations and find, compared to our previous TIGRESS/Schmidt model, a significant increase in the stellar scale heights and a slight increase in stellar mass. We demonstrate that modifying the effective equation of state significantly affects the morphology of simulated galaxies. Pronounced stellar clumps appear if the effective pressure at low hydrogen number densities is low, and disappear for higher pressure. We show that the formation of clumps is a result of Toomre instabilities, and conclude that simulated galaxy morphologies can be used to constrain effective equation of state models. Overall, our results establish PRFM-vol as a new self-consistent, physics-motivated subgrid model for star formation in high-resolution cosmological simulations.
Versions
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BibTeX
@misc{burger2026learning,
title = {{Learning the Universe with PRFM-vol: Introducing a new subgrid model for star formation in cosmological simulations}},
author = {Jan D. Burger and Volker Springel and Eve C. Ostriker and Chang-Goo Kim and Ulrich Steinwandel and Matthew C. Smith and Lars Hernquist and Greg L. Bryan and Rachel S. Somerville and Alon Gurman},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2606.10022},
eprint = {2606.10022},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2606.10022},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Learning the Universe with PRFM-vol: Introducing a new subgrid model for star formation in cosmological simulations
AU - Jan D. Burger
AU - Volker Springel
AU - Eve C. Ostriker
AU - Chang-Goo Kim
AU - Ulrich Steinwandel
AU - Matthew C. Smith
AU - Lars Hernquist
AU - Greg L. Bryan
AU - Rachel S. Somerville
AU - Alon Gurman
PY - 2026
DA - 2026/10/09
PB - arXiv
DO - 10.48550/arxiv.2606.10022
UR - https://arxiv.org/abs/2606.10022
AB - We introduce PRFM-vol, a new subgrid model for star formation in cosmological simulations that aims to increase the physical realism of cosmological simulations by leveraging results obtained with focused ISM simulations. We deploy a modified effective equation of state and calculate the star formation rate for each gas cell as a function of the ambient densities of gas, dark matter, and stars, based on the pressure-regulated feedback-modulated (PRFM) theory of star formation. Test simulations of our model in isolated galaxies show that we match PRFM predictions and TIGRESS scaling relations remarkably well, provided sufficiently high resolution is available. In particular, we are able to clearly demonstrate the impact of the stellar potential on the star formation rate, thereby retaining an important prediction of PRFM. We then apply our new model to cosmological multizoom simulations and find, compared to our previous TIGRESS/Schmidt model, a significant increase in the stellar scale heights and a slight increase in stellar mass. We demonstrate that modifying the effective equation of state significantly affects the morphology of simulated galaxies. Pronounced stellar clumps appear if the effective pressure at low hydrogen number densities is low, and disappear for higher pressure. We show that the formation of clumps is a result of Toomre instabilities, and conclude that simulated galaxy morphologies can be used to constrain effective equation of state models. Overall, our results establish PRFM-vol as a new self-consistent, physics-motivated subgrid model for star formation in high-resolution cosmological simulations.
ER -