CALET's Sensitivity to Dark Matter Annihilation in the Galactic Halo

TL;DR

CALET on the ISS measures high-energy cosmic rays with high precision, aiming to detect signals from dark matter annihilation in the galactic halo by analyzing fine spectral structures and improving existing limits.

Contribution

This paper predicts CALET's sensitivity to dark matter annihilation signals, especially for models with direct electron-positron production, and compares it to current constraints.

Findings

CALET can significantly improve dark matter annihilation limits.

Simulated CALET data supports detection of dark matter signals with specific annihilation channels.

High energy resolution enables detection of spectral features indicative of dark matter.

Abstract

CALET (Calorimetric Electron Telescope), installed on the ISS in August 2015, directly measures the electron+positron cosmic rays flux up to 20 TeV. With its proton rejection capability of 1:10^5 and an aperture of 1200 cm^2 sr, it will provide good statistics even well above one TeV, while also featuring an energy resolution of 2%, which allows it to detect fine structures in the spectrum. Such structures may originate from Dark Matter annihilation or decay, making indirect Dark Matter search one of CALET's main science objectives among others such as identification of signatures from nearby supernova remnants, study of the heavy nuclei spectra and gamma astronomy. The latest results from AMS-02 on positron fraction and total electron+positron flux can be fitted with a parametrization including a single pulsar as an extra power law source with exponential cut-off, which emits an equal amount of electrons and positrons. This single pulsar scenario for the positron excess is extrapolated into the TeV region and the expected CALET data for this case are simulated. Based on this prediction for CALET data, the sensitivity of CALET to Dark Matter annihilation in the galactic halo has been calculated. It is shown that CALET could significantly improve the limits compared to current data, especially for those Dark Matter candidates that feature a large fraction of annihilation directly into electron+positron, such as the LKP (Lightest Kaluza-Klein Particle).