A model of acceleration of Anomalous Cosmic Rays by Reconnection in the Heliosheath

TL;DR

This paper proposes a model where anomalous cosmic rays are accelerated through fast magnetic reconnection in the heliosheath, offering an alternative to shock-based acceleration, supported by Voyager spacecraft data.

Contribution

It introduces a novel reconnection-based acceleration model for cosmic rays, contrasting with traditional shock acceleration theories.

Findings

Voyager data supports reconnection-driven acceleration.

Magnetic field reversals are key energy sources.

Reconnection model aligns with observed cosmic ray spectra.

Abstract

We discuss a model of cosmic ray acceleration that accounts for the observations of anomalous cosmic rays by Voyager 1 and 2. The model appeals to fast magnetic reconnection rather than shocks as the driver of acceleration. The ultimate source of energy is associated with magnetic field reversals that occur in the heliosheath. It is expected that the magnetic field reversals will occur throughout the heliosheath, but especially near the heliopause where the flows slows down and diverge in respect to the interstellar wind and also in the boundary sector-in the heliospheric current sheet. While the First Order Fermi acceleration theory within reconnection layers is in its infancy, the available predictions do not contradict the available data on anomalous cosmic ray spectra measured by the spacecrafts. We argue that the Voyager data can be one of the first pieces of evidence favoring the acceleration within regions of fast magnetic reconnection, which we argue is a widely spread astrophysical process.