2008/11/22 by Stavros Dimitrakoudis, S. Dimitrakoudis, A. Mastichiadis +3
Physics and Astronomy · #Astrophysics and Cosmic Phenomena #Dark Matter and Cosmic Phenomena #Neutrino Physics Research #astro-ph
paper · pdf · doi:10.1016/j.astropartphys.2008.11.001
7 pages, 7 figures, accepted for publication in Astroparticle Physics
openalex publication_date 2008/11/22 · arxiv created 2008/12/02 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
Recent observations by the H.E.S.S. collaboration of the Galactic Centre region have revealed what appears to be gamma-ray emission from the decay of pions produced by interactions of recently accelerated cosmic rays with local molecular hydrogen clouds. Synthesizing a 3-D hydrogen cloud map from the available data and assuming a diffusion coefficient of the form kappa(E) = kappa0(E/E0)delta, we performed Monte Carlo simulations of cosmic ray diffusion for various propagation times and values of kappa0 and delta. By fitting the model gamma-ray spectra to the observed one we were able to infer the value of the diffusion coefficient in that environment (kappa = 3.0 +/- 0.2 kpc2 Myr-1 for E = 1012.5 eV and for total propagation time 104 yr) as well as the source spectrum (2.1 < gamma < 2.3). Also, we found that proton losses can be substantial, which justifies our approach to the problem.