X-ray measurements of nonthermal emission from the Abell 1367 galaxy cluster using the Rossi X-ray Timing Explorer

Observations with the Rossi X-Ray Timing Explorer (RXTE), the Advanced Sate llite for Astrophysics and Cosmology, and ROSAT have been used to search fo r X-ray emission produced by the inverse Compton process in the Abell 1367 galaxy cluster. The three data sets provide a high-quality spectrum which e xtends from 0.4 to 20 keV, allowing accurate separation of thermal and nont hermal components. In the cases of both the duster's radio halo relic and r adio galaxy 3C 264 the detection of nonthermal emission is model dependent. Nonthermal emission from the relic is detected using the RXTE Proportional Counter Array with a flux of similar to0.010-0.019 photons cm(-2) keV(-1) s(-1) at 1 keV, when the thermal emission is modeled with a single thermal component. However, modeling the thermal emission with two thermal componen ts provides a better fit to the data and obviates the need for a nonthermal power-law component. We also find that thermal emission is a physically pl ausible origin for the second component. Using two thermal components to mo del the spectrum gives an upper limit of 3.3 x 10(-3) photons cm(-2) keV(-1 ) s(-1) on nonthermal X-ray emission from the radio relic region. We derive an average intracluster magnetic field of greater than or equal to0.84 muG for this region. This value is consistent with the radial field derived fr om Faraday rotation studies of noncooling flow clusters. For the central re gion of the intracluster medium, we find an upper limit of 1.08 x 10(-3) ph otons cm(-2) keV(-1) s(-1) at 1 keV for nonthermal emission. Joint fitting of the data sets gives a detection of nonthermal emission for 3C 264 of 1.2 1 x 10(-4) to 2.45 x 10(-4) photons cm(-2) keV(-1) s(-1) at 1 keV, using a single thermal component. However, as with the radio relic region, two ther mal components provide a much better fit to the spectrum and give an upper limit of less than 5.3 x 10(-5) photons cm(-2) keV(-1) s(-1) at 1 keV. Comb ining the X-ray upper limit with the radio spectrum gives an average magnet ic field greater than 0.41 muG.