Confirmation of nonthermal hard X-ray excess in the coma cluster from two epoch observations

We report the hard X- ray spectrum of the Coma Cluster obtained using the Phoswich Detection System data of two independent BeppoSAX observations performed with a time interval of about 3 yr. In both the spectra a nonthermal excess with respect to the thermal emission is present at a confidence level of similar to 3.4 sigma. The combined spectrum obtained by adding up the two spectra allows a measurement of the excess at the level of similar to 4.8 sigma at energies above 20 keV. The analysis of the full BeppoSAX data set provides a revised nonthermal X- ray flux that is slightly lower than that previously estimated ( Fusco- Femiano et al.) and in agreement with that measured by two Rossi X- Ray Timing Explorer observations. The analysis of the offset fields in our Coma observations provides a possible flux determination of the BL Lac object 1ES 1255 + 244.