γ-ray Constraints on Decaying Dark Matter and Implications for IceCube.

Area of Science:

• Astrophysics
• Particle Physics
• Cosmology

Background:

• Dark matter (DM) is a major component of the universe, but its properties remain largely unknown.
• The decay of dark matter particles is a potential source of observable astrophysical signals.
• Previous studies have explored dark matter decay using various observational data.

Purpose of the Study:

• To derive stringent constraints on the lifetime of dark matter particles across a wide mass range.
• To test the hypothesis that dark matter decay can explain observed astrophysical anomalies, such as neutrino and positron fluxes.
• To interpret the constraints within specific dark matter models.

Main Methods:

• Analysis of 413 weeks of Fermi Pass 8 gamma-ray data from the Inner Galaxy.
• Utilizing profile-likelihood analysis with updated models for diffuse gamma-ray emission.
• Modeling both Galactic and extragalactic dark matter decay, including primary emission and inverse-Compton scattering.
• Calculating extragalactic flux contributions from cascade processes.

Main Results:

• Strongest constraints to date on dark matter lifetime for particle masses from MeV to EeV.
• Exclusion of decaying dark matter as an explanation for the IceCube neutrino flux (10 TeV-1 PeV).
• Challenging decaying dark matter as an explanation for the AMS-02 positron flux.

Conclusions:

• The Fermi gamma-ray data provide powerful constraints on dark matter properties.
• Decaying dark matter models face significant challenges in explaining current astrophysical observations.
• The results are interpreted in the context of simplified dark matter scenarios, including hidden-sector models.