The diffusion coefficient in the Large Magellanic Cloud

TL;DR

This paper develops a numerical model to study cosmic-ray transport in the Large Magellanic Cloud, using radio observations to estimate the diffusion coefficient, thereby enhancing understanding of cosmic-ray behavior in nearby galaxies.

Contribution

It introduces an end-to-end numerical framework extending existing codes to analyze cosmic-ray diffusion and non-thermal emission in the LMC, providing a method to infer diffusion coefficients from radio data.

Findings

Estimated the diffusion coefficient D0 = (3-6) × 10^{28} cm^2/s at 1 GeV in the LMC.

Compared the diffusion coefficient in the LMC to that of the Milky Way, finding it slightly larger.

Provided a scalable tool for interpreting non-thermal signals and cosmic-ray transport in nearby galaxies.

Abstract

The Large Magellanic Cloud (LMC) is the largest satellite galaxy of the Milky Way and provides a unique laboratory for high-energy astrophysics and dark matter studies. In this work, we develop an end-to-end numerical description of cosmic-ray transport and the associated non-thermal emission in the LMC, extending the public DRAGON and HERMES codes. Within this framework, we compute the diffuse synchrotron radiation produced by cosmic-ray electrons in the LMC and compare our predictions with observed low-frequency radio maps. Because electron diffusion imprints a characteristic morphology on the radio emission, this comparison allows us to infer the effective average diffusion coefficient in the LMC. We find a diffusion coefficient D0 = (3-6) $\times 10^{28} \; \rm{cm}^2 \; \rm{s}^{-1}$ at 1 GeV, comparable to but slightly larger than values typically inferred for the Milky Way. More generally, this work provides a scalable tool for interpreting non-thermal signals in nearby galaxies and constraining their cosmic-ray transport properties.