# The Galactic magnetic field in the light of starburst-generated ultrahigh-energy cosmic rays

## TL;DR

This paper explores how the observed distribution of ultrahigh-energy cosmic rays from starburst galaxies can be used to constrain models of the Galactic magnetic field, especially if the hot spot near M82 is confirmed as a source.

## Contribution

It demonstrates that UHECR arrival directions can provide strong constraints on the Galactic magnetic field models assuming starburst galaxies are their sources.

## Key findings

- UHECR data can constrain the Galactic magnetic field components.
- The hot spot near M82 is a key to understanding cosmic ray origins.
- Starburst galaxies are potential sources of UHECRs.

## Abstract

Auger data show evidence for a correlation between ultrahigh-energy cosmic rays (UHECRs) and nearby starburst galaxies. This intriguing correlation is consistent with data collected by the Telescope Array, which have revealed a much more pronounced directional ``hot spot'' in arrival directions not far from the starburst galaxy M82. In this work, we assume starbursts are sources of UHECRs and investigate the prospects to use the observed distribution of UHECR arrival directions to constrain Galactic magnetic field models. We show that if the Telescope Array hot spot indeed originates from M82, UHECR data would place a strong constraint on the coherent and turbulent components of the Galactic magnetic field.