Confirmation of non-thermal 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 PDS data of two independent BeppoSAX observations performed with a time interval of about three years. In both the spectra a non thermal excess with respect to the thermal emission is present at a confidence level of ∼ 3.4σ. The combined spectrum obtained by adding up the two spectra allows a measurement of the excess at the level of ∼ 4.8σ at energies above 20 keV. The analysis of the full BeppoSAX data set provides a revised non-thermal X-ray flux which is slightly lower than that previously estimated (Fusco-Femiano et al. 1999) and in agreement with that measured by two RXTE observations. The analysis of the offset fields in our Coma observations provides a possible flux determination of the BL Lac object 1ES 1255+244. Subject headings: cosmic microwave background — galaxies: clusters: individual (Coma) — magnetic fields — radiation mechanisms: non-thermal — X–rays: galaxies: BL Lacertae objects: individual (1ES 1255+244)