The universality of the relation between magnetic fields and star formation in galaxies

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Main Authors: Belfiori, Davide, Martin-Alvarez, Sergio, Lopez-Rodriguez, Enrique, Paladino, Rosita
Format: Preprint
Published: 2025
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author Belfiori, Davide
Martin-Alvarez, Sergio
Lopez-Rodriguez, Enrique
Paladino, Rosita
author_facet Belfiori, Davide
Martin-Alvarez, Sergio
Lopez-Rodriguez, Enrique
Paladino, Rosita
contents The interstellar medium (ISM) is permeated by magnetic fields that affect gas dynamics and star formation. These fields correlate with supernova (SN)-driven turbulence, but whether the scaling is universal across galaxy properties, ISM phases, and energy budgets remains unclear. We quantify the dependence of magnetic fields on star formation activity including both regular and starburst galaxies. We analyse 19 spiral disks from the cosmological RTnsCRiMHD Azahar suite, deriving line-of-sight integrated maps to measure median magnetic-field strength ($B$), specific energies (thermal, turbulent, magnetic, and cosmic-ray), and star formation rate (SFR), star formation surface density ($Σ_{\mathrm{SFR}}$) and specific SFR (sSFR). We find an almost universal magnetic-field-SFR scaling with slope $α\approx 0.2$-$0.3$ across galaxy mass and ISM phases. The $B$-$Σ_{\mathrm{SFR}}$ slope ($α\approx 1/3$) supports an SN-driven, turbulence-regulated origin. Neutral gas is generally turbulence-dominated and in near equipartition with magnetic energy for systems with sSFR $\gtrsim 0.1$ Gyr$^{-1}$ and SFR $\gtrsim 1$ $M_\odot$ yr$^{-1}$. The simulated trends match observations with similar slopes ($α\approx 0.25$-$0.35$), indicating that SN-driven turbulence is the main amplification mechanism behind the near-universal $B$-SFR relation.
format Preprint
id arxiv_https___arxiv_org_abs_2510_25909
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The universality of the relation between magnetic fields and star formation in galaxies
Belfiori, Davide
Martin-Alvarez, Sergio
Lopez-Rodriguez, Enrique
Paladino, Rosita
Astrophysics of Galaxies
The interstellar medium (ISM) is permeated by magnetic fields that affect gas dynamics and star formation. These fields correlate with supernova (SN)-driven turbulence, but whether the scaling is universal across galaxy properties, ISM phases, and energy budgets remains unclear. We quantify the dependence of magnetic fields on star formation activity including both regular and starburst galaxies. We analyse 19 spiral disks from the cosmological RTnsCRiMHD Azahar suite, deriving line-of-sight integrated maps to measure median magnetic-field strength ($B$), specific energies (thermal, turbulent, magnetic, and cosmic-ray), and star formation rate (SFR), star formation surface density ($Σ_{\mathrm{SFR}}$) and specific SFR (sSFR). We find an almost universal magnetic-field-SFR scaling with slope $α\approx 0.2$-$0.3$ across galaxy mass and ISM phases. The $B$-$Σ_{\mathrm{SFR}}$ slope ($α\approx 1/3$) supports an SN-driven, turbulence-regulated origin. Neutral gas is generally turbulence-dominated and in near equipartition with magnetic energy for systems with sSFR $\gtrsim 0.1$ Gyr$^{-1}$ and SFR $\gtrsim 1$ $M_\odot$ yr$^{-1}$. The simulated trends match observations with similar slopes ($α\approx 0.25$-$0.35$), indicating that SN-driven turbulence is the main amplification mechanism behind the near-universal $B$-SFR relation.
title The universality of the relation between magnetic fields and star formation in galaxies
topic Astrophysics of Galaxies
url https://arxiv.org/abs/2510.25909