Diffuse gamma emission of the Galaxy from cosmic rays

The diffuse gamma-rays and neutrino emissions of the Galaxy may provide a unique tool to probe galactic cosmic rays (CR) and their interaction with the interstellar medium. At the same time, if not well understood, such emissions may be annoying backgrounds for dark matter searches. Therefore, it is crucial to model them as better as possible. We do that by combining simulations of the CR propagation with recent models of the gas distribution. Respect to previous works, we perform a treatment of CR diffusion which accounts for a more realistic spatial dependence of the diffusion coefficients. Although our analysis is focused on the energy range above the TeV, we can reliably extrapolate our predictions at lower energies and compare them with EGRET measurements finding a good agreement. Then, we compare our predictions with MILAGRO and TIBET observations in several regions of the sky, including Cygnus and the Galactic Centre. Finally, we briefly discuss the implication of our finding for neutrino astronomy. (c) 2008 Elsevier B.V. All rights reserved.