Test of validity of the force-field approximation with AMS-02 and PAMELA monthly fluxes

TL;DR

This study evaluates the accuracy of the force-field approximation in modeling solar modulation of galactic cosmic rays using data from PAMELA and AMS-02, revealing the need for a rigidity-dependent modification for improved precision.

Contribution

The paper demonstrates that the traditional force-field approximation requires a rigidity-dependent adjustment to accurately fit AMS-02 and PAMELA cosmic ray flux data.

Findings

Force-field approximation needs a rigidity-dependent modification.

AMS-02 data precision surpasses the accuracy of the standard model.

Validation of the modified model improves cosmic ray flux predictions.

Abstract

Galactic cosmic rays (GCRs) entering the heliosphere are disturbed by the magnetic field of the Sun, which varies the shape and intensity of their local interstellar spectrum. The force-field approximation is a popular way of dealing with solar modulation, especially for studies focused on galactic transport of cosmic rays. The validity of this approach to reproduce the modulated GCR fluxes at Earth is tested using monthly proton fluxes measured by PAMELA between July 2006 and January 2014 and monthly proton and helium fluxes measured by AMS-02 between May 2011 and May 2017. We show that the precision of the new AMS-02 data requires a rigidity-dependent modification of the force-field approximation.