Dark Matter Annihilation in the light of EGRET, HEAT, WMAP, INTEGRAL and ROSAT (15'+5')

Abstract

The ROSAT Galactic wind observations confirm that our Galaxy launches supernova (SN) driven Galactic winds with wind speeds of about 150 km/s in the Galactic plane. Galactic winds of this strength are incompatible with current isotropic models for Cosmic Ray (CR) transport as implemented in the GALPROP code. In order to reproduce our local CRs in the presence of Galactic winds, charged CRs are required to be much more localized than in the standard isotropic GALPROP models. This requires that anisotropic diffusion is the dominant diffusion mode in the interstellar medium (ISM), particularly that the diffusion in the disk and in the halo are differ ent. In addition small scale phenomena such as trapping by molecular cloud complexes and the structure of our local environment (the local bubble or the local fluff) might influence the secondary CR production rate and our local CR density gradients. We introduce an anisotropic convection driven transport model (aCDM) which is consistent with the Galactic wind observations by ROSAT. This automatically explains the large bulge/disk ratio as observed by INTEGRAL. Furthermore such models predict an increase in the e + /(e + + e )fraction as observed by PAMELA and HEAT, if the synchrotron constraints in the 408 MHz and WMAP range are taken into account. This increase originates entirely from the transport properties of electrons and positrons, no additional contribut ion from Dark Matter (DM) is required. The aCDM is able to explain the absence of a positron annihilation signal from molecular clouds (MCs) as observed by INTEGRAL by virtue of a mechanism which confines and isotropizes CRs between MCs. Unlike isotropic models, this model does not rely on a flattened source distribution or a strong increase in the XCO scaling factor, but uses the supernova remnant (SNR) distribution as source distribution for CRs and a flat XCO scaling factor. We find that the EGRET excess of diffuse γ-rays currently cannot be explained by astrophysical effects in this type of model and that the interpretation of the EGRET excess as Dark Matter annihilation (DMA) is perfectly consistent with all observational constraints from local CR fluxes and s ynchrotron radiation.