# A New Model For The Loop-I (The North Polar Spur) Region

## TL;DR

This paper introduces a novel model of two interacting synchrotron shells to explain the large-scale polarized radio structures of the North Polar Spur, linking radio and X-ray observations with shell interactions.

## Contribution

It presents a new model involving two synchrotron shells that accounts for the observed polarization and X-ray emission in the Loop I region.

## Key findings

- Reproduces the polarized emission of the NPS with one shell.
- Suggests X-ray emission results from shell interactions.
- Links OB-associations to shell centers.

## Abstract

The North Polar Spur (NPS) is the brightest filament of Loop I, a large circular feature in the radio continuum sky. In this paper, a model consisting of two synchrotron emitting shells is presented that reproduces large-scale structures revealed by recent polarization surveys. The polarized emission of the NPS is reproduced by one of these shells. The other shell, which passes close to the Sun, gives rise to polarized emission towards the Galactic poles. It is proposed that X-ray emission seen towards the NPS is produced by interaction of the two shells. Two OB-associations coincide with the centers of the shells. A formation scenario of the Loop I region is suggested.