Resolving cosmic gamma ray anomalies with dark matter decaying now

Area of Science:

• Cosmology and Particle Physics
• Astrophysics

Background:

• Dark matter, a major component of the universe, is typically assumed to be stable.
• However, dark matter particles may undergo decay, influencing observable phenomena.
• The diffuse photon background and gamma-ray signals offer potential avenues for detection.

Purpose of the Study:

• To investigate the implications of decaying dark matter particles.
• To explore models including universal extra dimensions and supersymmetry for dark matter decay.
• To determine if decaying dark matter can explain the observed MeV gamma-ray excess.

Main Methods:

• Analysis of the diffuse photon background as a probe for dark matter decay.
• Consideration of very late decays of weakly interacting massive particles (WIMPs).
• Modeling decays into Kaluza-Klein gravitons and gravitinos within specific theoretical frameworks.

Main Results:

• Decaying dark matter, even with lifetimes exceeding the age of the universe, can be constrained by the diffuse photon background.
• The energy spectrum and flux of the observed MeV gamma-ray excess can be simultaneously explained by decaying dark matter with MeV mass splittings.
• This provides a potential explanation for a long-standing astrophysical puzzle.

Conclusions:

• Decaying dark matter is a viable explanation for the MeV gamma-ray excess.
• Future observations of photon fluxes will test this hypothesis.
• This research may yield novel constraints on cosmological parameters and dark matter properties.