The VariableTNG project: how baryonic mechanisms shape galaxy properties
Abstract
We use 50 Sobol-sampled VariableTNG simulations, varying eight subgrid parameters at fixed cosmology and initial conditions, to determine which baryonic processes regulate galaxies and black holes at z=6 and z=8. We compare the simulations with recent high-redshift measurements of the stellar mass function, star-forming main sequence, stellar and gas-phase mass-metallicity relations, stellar mass-size relation, and black-hole host and accretion properties. The simulations reproduce several broad trends in these observables, although differences remain in gas-phase metallicity, galaxy size, and the most extreme black-hole populations. Given the substantial uncertainties in both the physical modelling and the observational inference of high-redshift galaxy properties, we regard these differences as diagnostic tensions rather than definitive model failures. Random-forest analyses reveal a clear hierarchy in parameter sensitivity. The abundance of low-mass galaxies is regulated primarily by stellar feedback, particularly the supernova temperature TSN and thermal wind fraction τw, whereas the sensitivity of the scatter in the star-forming main sequence is weaker and redshift dependent. The high-accretion tail of black-hole growth depends on black-hole seeding and feedback parameters, but also on TSN, suggesting that stellar feedback indirectly regulates rapid black-hole growth through its impact on the available gas supply. Although cosmic variance can obscure these intrinsic responses in independent small volumes, our controlled experiment identifies stellar feedback as a common physical link between early low-mass galaxy formation and rapid black-hole growth.
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BibTeX
@misc{liu2026variabletng,
title = {{The VariableTNG project: how baryonic mechanisms shape galaxy properties}},
author = {Kexin Liu and Hong Guo and Luis C. Ho and Tao Wang and Yikai Liu and Volker Springel},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2608.17272},
eprint = {2608.17272},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.17272},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - The VariableTNG project: how baryonic mechanisms shape galaxy properties
AU - Kexin Liu
AU - Hong Guo
AU - Luis C. Ho
AU - Tao Wang
AU - Yikai Liu
AU - Volker Springel
PY - 2026
DA - 2026/09/21
PB - arXiv
DO - 10.48550/arxiv.2608.17272
UR - https://arxiv.org/abs/2608.17272
AB - We use 50 Sobol-sampled VariableTNG simulations, varying eight subgrid parameters at fixed cosmology and initial conditions, to determine which baryonic processes regulate galaxies and black holes at z=6 and z=8. We compare the simulations with recent high-redshift measurements of the stellar mass function, star-forming main sequence, stellar and gas-phase mass-metallicity relations, stellar mass-size relation, and black-hole host and accretion properties. The simulations reproduce several broad trends in these observables, although differences remain in gas-phase metallicity, galaxy size, and the most extreme black-hole populations. Given the substantial uncertainties in both the physical modelling and the observational inference of high-redshift galaxy properties, we regard these differences as diagnostic tensions rather than definitive model failures. Random-forest analyses reveal a clear hierarchy in parameter sensitivity. The abundance of low-mass galaxies is regulated primarily by stellar feedback, particularly the supernova temperature T_SN and thermal wind fraction τ_w, whereas the sensitivity of the scatter in the star-forming main sequence is weaker and redshift dependent. The high-accretion tail of black-hole growth depends on black-hole seeding and feedback parameters, but also on T_SN, suggesting that stellar feedback indirectly regulates rapid black-hole growth through its impact on the available gas supply. Although cosmic variance can obscure these intrinsic responses in independent small volumes, our controlled experiment identifies stellar feedback as a common physical link between early low-mass galaxy formation and rapid black-hole growth.
ER -