Hidden Sector Dark Matter and the Galactic Center Gamma-Ray Excess: A Closer Look

TL;DR

This paper explores hidden sector dark matter models that could explain the Galactic Center gamma-ray excess, analyzing their compatibility with current constraints and potential for future discrimination via cosmic-ray measurements.

Contribution

It provides detailed calculations of gamma-ray emissions in various hidden sector models and identifies parameter regions consistent with observations and constraints.

Findings

Hidden sector models can explain the gamma-ray excess.

Certain models remain consistent with relic abundance and experimental constraints.

Cosmic-ray antiproton data could distinguish these models from conventional dark matter scenarios.

Abstract

Stringent constraints from direct detection experiments and the Large Hadron Collider motivate us to consider models in which the dark matter does not directly couple to the Standard Model, but that instead annihilates into hidden sector particles which ultimately decay through small couplings to the Standard Model. We calculate the gamma-ray emission generated within the context of several such hidden sector models, including those in which the hidden sector couples to the Standard Model through the vector portal (kinetic mixing with Standard Model hypercharge), through the Higgs portal (mixing with the Standard Model Higgs boson), or both. In each case, we identify broad regions of parameter space in which the observed spectrum and intensity of the Galactic Center gamma-ray excess can easily be accommodated, while providing an acceptable thermal relic abundance and remaining consistent with all current constraints. We also point out that cosmic-ray antiproton measurements could potentially discriminate some hidden sector models from more conventional dark matter scenarios.