# Breaks in interstellar spectra of positrons and electrons derived from time-dependent AMS data

## TL;DR

This paper models cosmic ray electrons and positrons using a diffusion model that fits multiple datasets, revealing spectral breaks that inform understanding of cosmic ray acceleration and transport.

## Contribution

It introduces a comprehensive, time-dependent diffusion model that fits diverse cosmic ray data and identifies spectral breaks in electron and positron spectra.

## Key findings

- Successfully reproduces all current measurements of cosmic ray electrons and positrons.
- Identifies the necessity of spectral breaks in source spectra and diffusion coefficients.
- Models time-dependent fluxes of cosmic ray electrons and positrons at GeV energies.

## Abstract

Until fairly recently, it was widely accepted that local cosmic ray spectra were largely featureless power laws, containing limited information on their acceleration and transport. This viewpoint is currently being revised in the light of evidence for a variety of spectral breaks in the fluxes of cosmic ray nuclei. Here, we focus on cosmic ray electrons and positrons which at the highest energies must be of local origin due to strong radiative losses. We consider a pure diffusion model for their Galactic transport and determine its free parameters by fitting data in a wide energy range: measurements of the interstellar spectrum by Voyager at MeV energies, radio synchrotron data (sensitive to GeV electrons and positrons) and local observations by AMS up to ~ 1 TeV. For the first time, we also model the time-dependent fluxes of cosmic ray electrons and positrons at GeV energies recently presented by AMS, treating solar modulation in a simple extension of the widely used force-field approximation. We are able to reproduce all the available measurements to date. Our model of the interstellar spectrum of cosmic ray electrons and positrons requires the presence of a number of spectral breaks, both in the source spectra and the diffusion coefficients. While we remain agnostic as to the origin of these spectral breaks, their presence will inform future models of the microphysics of cosmic ray acceleration and transport.