Boxes, Boosts, and Energy Duality: Understanding the Galactic-Center Gamma-Ray Excess through Dynamical Dark Matter

TL;DR

The paper proposes that the gamma-ray excess from the Galactic Center exhibits an energy-duality symmetry, which can reveal key properties of the dark matter sector through a simple kinematic interpretation within the Dynamical Dark Matter framework.

Contribution

It introduces the concept of energy-duality invariance in gamma-ray spectra and links it to a simple kinematic model in the context of Dynamical Dark Matter, offering a new perspective on the Galactic Center excess.

Findings

Gamma-ray spectrum shows energy-duality invariance under E_gamma to E_*^2 / E_gamma.

Energy duality suggests a simple underlying kinematic mechanism.

Potential to extract dark sector properties from spectral symmetry.

Abstract

Many models currently exist which attempt to interpret the excess of gamma rays emanating from the Galactic Center in terms of annihilating or decaying dark matter. These models typically exhibit a variety of complicated cascade mechanisms for photon production, leading to a non-trivial kinematics which obscures the physics of the underlying dark sector. In this paper, by contrast, we observe that the spectrum of the gamma-ray excess may actually exhibit an intriguing "energy-duality" invariance under $E_\gamma \rightarrow E_\ast^2/E_\gamma$ for some $E_\ast$. As we shall discuss, such an energy duality points back to a remarkably simple alternative kinematics which in turn is realized naturally within the Dynamical Dark Matter framework. Observation of this energy duality could therefore provide considerable information about the properties of the dark sector from which the Galactic-Center gamma-ray excess might arise, and highlights the importance of acquiring more complete data for the Galactic-Center excess in the energy range around 1 GeV.