Indirect effects of dark matter

TL;DR

This paper reviews potential indirect effects of dark matter, focusing on cosmic ray anomalies and gamma-ray constraints, exploring models to reconcile observations with dark matter decay or annihilation scenarios.

Contribution

It investigates how dark matter decay or annihilation could explain cosmic ray excesses while remaining consistent with gamma-ray observations, proposing specific model modifications.

Findings

Gamma-ray background constrains dark matter decay/annihilation interpretations.

Certain decay modes with identical fermions may evade gamma-ray constraints.

Spatial distribution variations of dark matter can reconcile data.

Abstract

Here we briefly review possible indirect effects of dark matter (DM) of the Universe. It includes effects in cosmic rays (CR): first of all, the positron excess at $\sim$ 500 GeV and possible electron-positron excess at 1-1.5 TeV. We tell that the main and least model-dependent constraint on such possible interpretation of CR effects goes from gamma-ray background. Even ordinary $e^+e^-$ mode of DM decay or annihilation produces prompt photons (FSR) so much that leads to contradiction with data on cosmic gamma-rays. We present our attempts to possibly avoid gamma-ray constraint. They concern peculiarities of both space distribution of DM and their physics. The latter involves complications of decay/annihilation modes of DM, modifications of Lagrangian of DM-ordinary matter interaction, and inclusion of mode with identical fermions in final state. In this way, no possibilities to suppress were found except, possibly, mode with identical fermions. While the case of spatial distribution variation allows achieving consistency between different data. Also we consider stable form of dark matter which can interact with baryons. We show which constraint such DM candidate can get from damping effect in plasma during large scale structure formation in comparison with other existing constraints.