An Interpretation of the Cosmic Ray $e^+\, +\, e^-$ Spectrum from 10 GeV to 3 TeV Measured by CALET on the ISS

TL;DR

This paper interprets the combined CALET and AMS-02 cosmic ray electron and positron spectra up to 3 TeV, exploring whether pulsars or dark matter decay best explain the observed positron excess, and assesses CALET's ability to distinguish these sources.

Contribution

It introduces a combined analysis of CALET and AMS-02 data, evaluating dark matter decay and pulsar models as sources of the positron excess, and discusses CALET's potential to differentiate these scenarios.

Findings

Both dark matter decay and pulsar models can explain the data.

A 800 GeV dark matter decay scenario is compatible with gamma-ray constraints.

CALET can potentially distinguish between dark matter and pulsar sources.

Abstract

A combined interpretation of the CALET $e^+\, +\, e^-$ spectrum up to 3 TeV and the AMS-02 positron spectrum up to 500 GeV was performed and the results are discussed. To parametrize the background electron flux, we assume a smoothly broken power-law spectrum with an exponential cut-off for electrons and fit this parametrization to the measurements, with either a pulsar or 3-body decay of fermionic Dark Matter as the extra electron-positron pair source responsible for the positron excess. We found that depending on the parameters for the background, both Dark Matter decay and the pulsar model can explain the combined measurements. While the Dark Matter decay scenario is constrained by the Fermi-LAT $\gamma$-ray measurement, we show that 3-body decay of a 800 GeV Dark Matter can be compatible with the $\gamma$-ray flux measurement. We discuss the capability of CALET to discern decaying Dark Matter models from a generic pulsar source scenario, based on simulated data for five years of data-taking.