Magnetic fields of our Galaxy on large and small scales

TL;DR

This paper reviews the observations of magnetic fields across all scales in our Galaxy, highlighting their structure, alignment with spiral arms, and the connection between large-scale and small-scale magnetic fields.

Contribution

It provides a comprehensive overview of Galactic magnetic field measurements and their implications for understanding magnetic field structure and distribution.

Findings

Large-scale magnetic fields align with spiral arms.

Magnetic field directions reverse multiple times across the Galaxy.

Small-scale fields in star-forming regions show structured patterns.

Abstract

Magnetic fields have been observed on all scales in our Galaxy, from AU to kpc. With pulsar dispersion measures and rotation measures, we can directly measure the magnetic fields in a very large region of the Galactic disk. The results show that the large-scale magnetic fields are aligned with the spiral arms but reverse their directions many times from the inner-most arm (Norma) to the outer arm (Perseus). The Zeeman splitting measurements of masers in HII regions or star-formation regions not only show the structured fields inside clouds, but also have a clear pattern in the global Galactic distribution of all measured clouds which indicates the possible connection of the large-scale and small-scale magnetic fields.