Time-dependent AMS-02 electron-positron fluxes in an extended force-field model

Abstract

The magnetised solar wind modulates the Galactic cosmic ray flux in the heliosphere up to rigidities as high as 40 GeV. In this work, we present a new and straightforward extension of the popular, but limited force-field model, thus providing a fast and robust method for phenomenological studies of Galactic cosmic rays. Our semi-analytical approach takes into account charge-sign dependent modulation due to drifts in the heliospheric magnetic field and has been validated via comparison to a fully numerical code. Our model nicely reproduces the time-dependent AMS-02 measurements and we find the strength of diffusion and drifts to be strongly correlated with the heliospheric tilt angle and magnitude of the magnetic field. We are able to predict the electron and positron fluxes beyond the range for which measurements by AMS-02 have been presented. We have made an example script for the semi-analytical model publicly available and we urge the community to adopt this approach for phenomenological studies.