7 keV Scalar Dark Matter and the Anomalous Galactic X-ray Spectrum

Understand

We present a simple model for a 7 keV scalar dark matter particle which also explains the recently reported anomalous peak in the galactic X-ray spectrum at 3.55 keV in terms of its two photon decay.

• The model is arguably the simplest extension of the Standard Model, with the addition of a real scalar gauge singlet field subject to a reflection symmetry.
• This symmetry breaks spontaneously at an energy scale of a few MeV which triggers the decay of the dark matter particle into two photons.
• In this framework, the Higgs boson of the Standard Model is also the source of dark matter in the Universe.