How Local is the Local Interstellar Magnetic Field?

TL;DR

This paper synthesizes diverse observational data to conclude that the local interstellar magnetic field's direction is coherent over approximately 100 parsecs, indicating a large-scale magnetic structure in our galactic neighborhood.

Contribution

It integrates multiple data sources to demonstrate the coherence scale of the local interstellar magnetic field, providing insights into its spatial extent and structure.

Findings

The local ISMF direction is consistent across various data types.

The ISMF is coherent over scales of about 100 parsecs.

The heliosphere tail-in excess of cosmic rays aligns with the ISMF direction.

Abstract

Similar directions are obtained for the local interstellar magnetic field (ISMF) by comparing diverse data and models that sample five orders of magnetic in spatial scales. These data include the ribbon of energetic neutral atoms discovered by the Interstellar Boundary Explorer, heliosphere models, the linear polarization of light from nearby stars, the Loop I ISMF, and pulsars that are within 100--300 pc. Together these data suggest that the local ISMF direction is correlated over scales of about 100 pc, such as would be expected for the interarm region of the galaxy. The heliosphere tail-in excess of GeV cosmic rays is consistent with the direction of the local ISMF direction found from polarization data.