Title: MEASURING THE HARD X-RAY SPECTRUMOF CLUSTERS OF GALAXIES WITH INTEGRAL

Title: MEASURING THE HARD X-RAY SPECTRUMOF CLUSTERS OF GALAXIES WITH INTEGRAL

Proposal ID: 0120143
Subject category: Extragalactic Object
Principal investigator: Petrosian
Institute: Stanford University

Abstract

We propose INTEGRAL observations of hard X-ray/soft-gamma-ray emission in clusters of galaxies, to determine and characterize the nature of the hard spectral component, beyond the thermal X-ray emission detected by RXTE and {\it Beppo}SAX in several clusters. We wish to measure the spectrum of such a component in one previously detected (A2256 for 150 ks) and two new candidates (A2163 and A1914 for 250 ks each), where such emission is predicted by our criteria based on their soft X-ray and radio data. Detailes of such a hard component are likely to reveal the nature of the emission process and the acceleration mechanism of the relativistic electrons, and aid in understanding the process of formation of clusters.