Abstract
Observations with the Fermi Large Area Telescope (LAT) indicate an excess in gamma rays originating from the center of our Galaxy. A possible explanation for this excess is the annihilation of Dark Matter particles. We have investigated the annihilation of neutralinos as Dark Matter candidates within the phenomenological Minimal Supersymmetric Standard Model (pMSSM) . An iterative particle filter approach was used to search for solutions within the pMSSM . We found solutions that are consistent with astroparticle physics and collider experiments, and provide a fit to the energy spectrum of the excess. The neutralino is a Bino/Higgsino or Bino/Wino/Higgsino mixture with a mass in the range 84–92 GeV or 87–97 GeV annihilating into W bosons. A third solutions is found for a neutralino of mass 174–187 GeV annihilating into top quarks. The best solutions yield a Dark Matter relic density 0.06 < Ω h2 <0.13. These pMSSM solutions make clear forecasts for LHC, direct and indirect DM detection experiments. If the pMSSM explanation of the excess seen by Fermi-LAT is correct, a DM signal might be discovered soon.
Highlights
We have investigated the annihilation of neutralinos as Dark Matter candidates within the phenomenological Minimal Supersymmetric Standard Model
In our exploration of the phenomenological Minimal Supersymmetric Standard Model (pMSSM) parameter space we find that requiring a χ210 < 40 implies the following three pMSSM parameter ranges: 4.1.1 WW solution 1: Bino-Higgsino neutralino
The reason is that even being away of the A-funnel region the neutralino coupling to pseudoscalars is enhanced due to their bino-higgsino nature and their annihilation to pairs of b-quarks. This solution provides a good fit to the Galactic Center photon spectrum as measured by Fermi. This is partly due to the fact that we, in contrast to previous studies, allow for an additional 10% uncorrelated uncertainty on the predicted photon energy spectrum, as discussed and motivated in appendix A
Summary
The observed gamma-ray flux from DM annihilation per unit solid angle at some photon energy Eγ is given by dΦγ (Eγ ) dEγ dΩ. The net effect is difficult to determine in general, but recent simulations that combine DM with hydrodynamics for the baryonic content [122] show a flattening of the density profile for Mily Way like spiral galaxies (2) The normalization of the DM density distribution is difficult to determine It is usually parametrized by the DM density at the galactocentric distance of the Sun, ρDM(r ). In order to search for corroborating evidence for the Dark Matter interpretation of the excess, it is important to estimate the uncertainties of its spectral properties conservatively. We adopt here the results from [118], where the excess emission was studied at latitudes above 2 degree This region is very sensitive to a Dark Matter signal, but avoids the much more complicated Galactic Center region. In the case that the DM origin of the GeV excess is supported by other experiments, these additional uncertainties require further study
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
