Integral Observations of Galaxy

Cluster of galaxies are the largest concentration of visible mass in the universe and therefore a fundamental topic of cosmology and astrophysics. Recent radio, EUV, and X-ray observations suggest that clusters contain large populations of diiuse non-thermal relativistic and/or superthermal particles. These particles may be produced by acceleration in cluster merger shocks, AGNs, and/or supernovae in cluster galaxies. Models for the nonthermal populations in clusters indicate that they should produce substantial hard X-ray and luminosities. The possible role of nonthermal particles in the dynamics of clusters is one of the greatest uncertainties in their use as cosmological probes. INTEGRAL ooers, for the rst time, the possibility of simultaneous medium resolution imaging (12 arcmin) and high resolution spectroscopy ((E/E 2 keV @ 1.3 MeV) with exceptional sensitivity in the hard X-ray/soft-ray band. The spatial resolution will allow discrete sources, such as AGNs, to be separated from the diiuse emission of the cluster. For nearby clusters, the spatial distribution of emission can be determined and compared to models for the nonthermal particle populations and observations in other wavebands. The spectral capabilities may allow diierent components of the nonthermal population to be detected separately. We present simulations of INTEGRAL observations of nearby galaxy clusters that show its capability for detecting the diierent phenomena responsible of clusters emission.