A New Model of the Galactic Magnetic Field

TL;DR

This paper introduces an enhanced model of the Galactic Magnetic Field using extensive observational data, incorporating out-of-plane and striated components, leading to better alignment with observed galactic phenomena.

Contribution

The paper presents a significantly generalized GMF model that includes out-of-plane and striated fields, improving fit to observational data compared to previous models.

Findings

Detection of a large out-of-plane magnetic component.

Better fit to synchrotron emission observations.

Evidence for higher cosmic ray electron density or widespread striated fields.

Abstract

A new, much improved model of the Galactic Magnetic Field (GMF) is presented. We use the WMAP7 Galactic Synchrotron Emission map and more than forty thousand extragalactic rotation measures to constrain the parameters of the GMF model, which is substantially generalized compared to earlier work to now include an out-of-plane component (as suggested by observations of external galaxies) and striated-random fields (motivated by theoretical considerations). The new model provides a greatly improved fit to observations. Consistent with our earlier analyses, the best-fit model has a disk field and an extended halo field. Our new analysis reveals the presence of a large, out-of-plane component of the GMF; as a result, the polarized synchrotron emission of our Galaxy seen by an edge-on observer is predicted to look intriguingly similar to what has been observed in external edge-on galaxies. We find evidence that the cosmic ray electron density is significantly larger than given by GALPROP, or else that there is a widespread striated component to the GMF.