Indirect Detection of Dark Matter and Uncertainties in Cosmic Ray Propagation

by Phill Grajek (VUB (Pheno-group))

Friday 18 Feb 2011, 14:00 → 15:00 Europe/Brussels

Large seminar room (1G-003) (IIHE(ULB-VUB))

Cosmic ray observations reveal an anomalous positron flux in excess of the expected astrophysical background. Possible explanations include pulsars and also exotic contributions such as annihilating dark matter particles. The SUSY neutralino makes a cosmologically attractive dark matter candidate, and neutralino annihilations may explain the positron excess. However, under traditional assumptions about how cosmic rays propagate throughout the galaxy, neutralino annihilations over-produce the flux of anti-protons. Recently a new cosmic ray propagation model was introduced by de Boer and Gebauer, which incorporates anisotropic diffusion as a way to accomodate strong galactic winds suggested by analysis of ROSAT X-ray data. These modifications lead to a reduced anti-proton flux relative to the PAMELA measurement, suggesting that an excess has been observed in this channel as well. In my talk I will review the anomalous positron signals and some potential physical explanations. Then I will discuss the canonical cosmic ray propagation scenario, the motivations for its modification, and the modifications themselves. Finally I will discuss some recent work attempting to fit this enhanced model to measured flux ratios as well as the PAMELA anti-proton ratio.

Slides iihe_18Feb2011-2.pdf