The impact of primordial magnetic fields on the formation of galaxies
Abstract
Primordial magnetic fields (PMFs), potentially generated during cosmic inflation or early-universe phase transitions, can modify cosmic structure formation by enhancing the post-recombination matter power spectrum. In this work, we investigate the impact of PMFs on galaxy formation using a suite of high-resolution cosmological hydrodynamical simulations evolved to z=0. Our simulations are initialized with PMF-induced enhancements to the matter power spectrum and include more comprehensive baryonic subgrid models than previous work, incorporating both stellar and AGN feedback. We find that PMFs systematically accelerate early structure formation, producing more abundant halos and galaxies, higher baryon fractions, enhanced star formation rates, and rapid growth of supermassive black holes at high redshifts (z ∼ 10). However, the resulting enhanced stellar and AGN feedback efficiently processes and expels gas, reducing the late-time differences between PMF and standard ΛCDM models. The PMF signatures are therefore strongest at high redshift and gradually weaken toward low redshift as nonlinear evolution and baryonic feedback dominate over the initial PMF-induced enhancements. The impact of PMFs depends strongly on the characteristic peak scale, kpeak, of the initial power enhancement, with models yielding similar non-linear evolution if they share a similar kpeak, even when other PMF parameters differ. Our results highlight the critical role of comprehensive baryonic physics in accurately quantifying PMF signatures.
Versions
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BibTeX
@misc{li2026impact,
title = {{The impact of primordial magnetic fields on the formation of galaxies}},
author = {Yao-Yu Li and Shihong Liao and Yue-Lin Sming Tsai and Yi-Zhong Fan},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.39399},
eprint = {2609.39399},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.39399},
}
RIS
TY - UNPB
TI - The impact of primordial magnetic fields on the formation of galaxies
AU - Yao-Yu Li
AU - Shihong Liao
AU - Yue-Lin Sming Tsai
AU - Yi-Zhong Fan
PY - 2026
DA - 2026/09/30
PB - arXiv
DO - 10.48550/arxiv.2609.39399
UR - https://arxiv.org/abs/2609.39399
AB - Primordial magnetic fields (PMFs), potentially generated during cosmic inflation or early-universe phase transitions, can modify cosmic structure formation by enhancing the post-recombination matter power spectrum. In this work, we investigate the impact of PMFs on galaxy formation using a suite of high-resolution cosmological hydrodynamical simulations evolved to z=0. Our simulations are initialized with PMF-induced enhancements to the matter power spectrum and include more comprehensive baryonic subgrid models than previous work, incorporating both stellar and AGN feedback. We find that PMFs systematically accelerate early structure formation, producing more abundant halos and galaxies, higher baryon fractions, enhanced star formation rates, and rapid growth of supermassive black holes at high redshifts (z ∼ 10). However, the resulting enhanced stellar and AGN feedback efficiently processes and expels gas, reducing the late-time differences between PMF and standard ΛCDM models. The PMF signatures are therefore strongest at high redshift and gradually weaken toward low redshift as nonlinear evolution and baryonic feedback dominate over the initial PMF-induced enhancements. The impact of PMFs depends strongly on the characteristic peak scale, k_peak, of the initial power enhancement, with models yielding similar non-linear evolution if they share a similar k_peak, even when other PMF parameters differ. Our results highlight the critical role of comprehensive baryonic physics in accurately quantifying PMF signatures.
ER -