Uncertainties in the Magnetic Field of the Milky Way

TL;DR

This paper refines models of the Milky Way's magnetic field by incorporating new data and alternative parameterizations, quantifying uncertainties that affect cosmic-ray astronomy.

Contribution

It introduces new functional forms and utilizes updated synchrotron data to better constrain the Galactic Magnetic Field models and assess their uncertainties.

Findings

Different model parameterizations lead to varying GMF structures.

Uncertainties in the GMF significantly impact ultra-high-energy cosmic-ray studies.

Updated electron density models influence the inferred magnetic field configurations.

Abstract

We improve on the model of the Galactic Magnetic Field (GMF) from Jansson \& Farrar (2012), which was constrained using all-sky rotation measures of extragalactic sources and polarized and unpolarized synchrotron emission data from WMAP. We have developed several alternative functional forms for the coherent and random components, used newer synchrotron products from Planck and WMAP and testes new models of the densities of thermal electrons and cosmic-ray electrons. The differences in the resultant GMF models, depending on which parameterization of the field, synchrotron product and electron densities are used, provides a measure of the uncertainty in our inference of the GMF. We discuss the impact of these uncertainties on charged-particle astronomy at ultra-high energies.