The radiation belt of the Sun

TL;DR

This paper predicts a belt-like structure of cosmic ray electrons and positrons around the Sun, caused by sunlight Compton drag depopulating quasi-bound orbits, based on first-principles calculations.

Contribution

It introduces a first-principles method to calculate near-Sun cosmic ray densities without diffusion assumptions, revealing a belt structure influenced by the solar magnetic field.

Findings

Electron/positron density forms a belt-like dent near the Sun.

The belt extends to several solar radii under certain magnetic conditions.

Sunlight Compton drag dominates over diffusion in this context.

Abstract

For a given solar magnetic field, the near-Sun (phase-space) density of cosmic ray electrons and positrons of energy above about 10GeV can be calculated from first principles, without any assumptions about the cosmic ray diffusion. This is because the sunlight Compton drag must be more important than diffusion. If the solar magnetic field has an appreciable dipole component, the electron/positron density should have a belt-like dent, perhaps extending to several solar radii. The belt structure appears because the quasi-bound orbits are depopulated by the sunlight Compton drag.