Accurate Inverse-Compton Models Strongly Enhance Leptophilic Dark Matter Signals

TL;DR

Modeling inverse-Compton scattering as a stochastic process significantly increases the predicted cosmic-ray electron-positron flux from leptophilic dark matter annihilation, improving detection prospects for heavy dark matter.

Contribution

This work introduces a stochastic modeling approach for inverse-Compton scattering, revealing a substantial increase in predicted signals compared to traditional continuous models.

Findings

Flux near dark matter mass is about twice as high with stochastic modeling.

Enhanced flux improves detectability of heavy leptophilic dark matter.

Stochastic effects are crucial for accurate indirect dark matter detection predictions.

Abstract

The annihilation of TeV-scale leptophilic dark matter into electron-positron pairs (hereafter $e^+e^-$) will produce a sharp cutoff in the local cosmic-ray $e^+e^-$ spectrum at an energy matching the dark matter mass. At these high energies, $e^+e^-$ cool quickly due to synchrotron interactions with magnetic fields and inverse-Compton scattering with the interstellar radiation field. These energy losses are typically modelled as a continuous process. However, inverse-Compton scattering is a stochastic energy-loss process where interactions are rare but catastrophic. We show that when inverse-Compton scattering is modelled as a stochastic process, the expected $e^+e^-$ flux from dark matter annihilation is about a factor of $\sim$2 larger near the dark matter mass than in the continuous model. This greatly enhances the detectability of heavy dark matter annihilating to $e^+e^-$ final states.