Physics (Internal)

Hidden Sector Dark Matter: The Galactic Center Gamma-Ray Excess and Indirect Detection Constraints

This event is part of the HET Seminar Series.

If dark matter is embedded in a non-trivial hidden sector, it may annihilate and decay to lighter hidden sector states which subsequently decay to Standard Model particles. While remaining agnostic to the details of the hidden sector model, our framework - with annihilations followed by cascading hidden sector decays - captures the generic broadening of the spectrum of secondary particles (photons, neutrinos, electron-positrons, and antiprotons) relative to the case of dark matter annihilating directly to Standard Model particles. I will detail how such scenarios can explain the apparent excess in GeV gamma-rays identified in the central Milky Way, while evading bounds from direct detection experiments. Additionally I will describe how indirect constraints on dark matter annihilation limit the parameter space for such cascade/multi-particle decays. In particular I will describe an investigation of the limits from the cosmic microwave background by Plank, the Fermi measurements of photons from the Milky Way Dwarf Spheroidal Galaxies, and positron data from AMS-02. Generally the bound from the Fermi dwarfs is the most constraining for annihilations to photon-rich final states, while AMS-02 is most constraining for electron and muon final states; however in certain instances the CMB bounds overtake both, due to their approximate independence of the details of the hidden sector cascade.