High energyγ-ray emission from the starburst nucleus of NGC 253

Abstract
The high density medium that characterizes the central regions of starburst galaxies and its power to accelerate particles up to relativistic energies make these objects good candidates as $\gamma$-rays sources. In this paper, a self-consistent model of the multifrequency emission of the starburst galaxy NGC 253, from radio to gamma-rays, is presented. The model is in agreement with all current measurements and provides predictions for the high energy behavior of the NGC 253 central region. Prospects for observations with the HESS array and GLAST satellite are especially discussed.Comment: 17 pages, 13 figures. To appear in A&A. Modelling parameters and results are unchanged from the previous version but we enhance here the detail with which they are described. 3 new figures and 1 new section have been added, including a figure showing the consistency of the model with the recently reported HESS observations (astro-ph/0507370) of NGC 25