A Unified Charge-Dependent Modulation Model for AMS-02 Proton and Antiproton Fluxes during Solar Minimum

TL;DR

This paper presents a comprehensive charge-dependent solar modulation model for cosmic ray protons and antiprotons during solar minimum, integrating drift effects and using neural networks for efficient parameter fitting.

Contribution

It introduces a unified, charge-dependent modulation model that self-consistently includes drift effects and employs neural networks for rapid parameter estimation.

Findings

Model accurately fits AMS-02 proton and antiproton flux data.

Provides a physically consistent description of charge-dependent solar modulation.

Demonstrates the effectiveness of neural networks in cosmic ray propagation modeling.

Abstract

We develop a unified charge-dependent solar modulation model by solving the three-dimensional Parker transport equation, incorporating a realistic wavy heliospheric current sheet to treat drift effects self-consistently. Using a local interstellar spectrum from GALPROP constrained by Voyager data, we fit the model to time-resolved proton and antiproton fluxes measured by the Alpha Magnetic Spectrometer - 02 (AMS-02) during the solar-quiet period (May 2011 to June 2022). To enable rapid parameter scans, we employ neural-network-based surrogate models to compute propagation and modulation matrices efficiently. The results demonstrate that the model simultaneously describes the observed proton and antiproton fluxes with physically reasonable parameters, providing a unified account of charge-dependent modulation.