<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Dimitrakoudis, Stavros</style></author><author><style face="normal" font="default" size="100%">Mastichiadis, Apostolos</style></author><author><style face="normal" font="default" size="100%">Geranios, Athanasios</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Obtaining the diffusion coefficient for cosmic ray propagation in the Galactic Centre Ridge through time-dependent simulations of their γ-ray emission</style></title><short-title><style face="normal" font="default" size="100%">Astroparticle Physics</style></short-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Astrophysics</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2009</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2009/02/1</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">https://ui.adsabs.harvard.edu/abs/2009APh....31...13D</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">31</style></volume><pages><style face="normal" font="default" size="100%">13 - 18</style></pages><isbn><style face="normal" font="default" size="100%">0927-6505</style></isbn><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Recent observations by the H.E.S.S. collaboration of the Galactic Centre region have revealed what appears to be γ-ray emission from the decay of pions produced by interactions of recently accelerated cosmic rays with local molecular hydrogen clouds. Synthesizing a 3D hydrogen cloud map from the available data and assuming a diffusion coefficient of the form κ(E) = κ&lt;SUB&gt;0&lt;/SUB&gt;(E/E&lt;SUB&gt;0&lt;/SUB&gt;)&lt;SUP&gt;δ&lt;/SUP&gt;, we performed Monte Carlo simulations of cosmic ray diffusion for various propagation times and values of κ&lt;SUB&gt;0&lt;/SUB&gt; and δ. By fitting the model γ-ray spectra to the observed one we were able to infer the value of the diffusion coefficient in that environment (κ = 3.0 ± 0.2 kpc&lt;SUP&gt;2&lt;/SUP&gt; Myr&lt;SUP&gt;-1&lt;/SUP&gt; for E = 10&lt;SUP&gt;12.5&lt;/SUP&gt; eV and for total propagation time 10&lt;SUP&gt;4&lt;/SUP&gt; yr) as well as the source spectrum (2.1 ⩽ γ ⩽ 2.3). Also, we found that proton losses can be substantial, which justifies our approach to the problem.</style></abstract></record></records></xml>