GALAXY CLUSTERS IN THE SWIFT /BURST ALERT TELESCOPE ERA: HARD X-RAYS IN THE INTRACLUSTER MEDIUM
Author(s)Ajello, M.; Rebusco, Paola; Cappelluti, N.; Reimer, O.; Böhringer, H.; Greiner, J.; Gehrels, N.; Tueller, J.; Moretti, A.; ... Show more Show less
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We report the detection of 10 clusters of galaxies in the ongoing Swift/Burst Alert Telescope (BAT) all-sky survey. This sample, which mostly comprises merging clusters, was serendipitously detected in the 15-55 keV band. We use the BAT sample to investigate the presence of excess hard X-rays above the thermal emission. The BAT clusters do not show significant (e.g., ≥2σ) nonthermal hard X-ray emission. The only exception is represented by Perseus whose high-energy emission is likely due to NGC 1275. Using XMM-Newton, Swift/XRT, Chandra and BAT data, we are able to produce upper limits of the inverse Compton (IC) emission mechanism which are in disagreement with most of the previously-claimed hard X-ray excesses. The coupling of the X-ray upper limits of the IC mechanism to radio data shows that, in some clusters, the magnetic field might be larger than 0.5 μG. We also derive the first log N-log S and luminosity function distributions of galaxy clusters above 15 keV.
DepartmentMIT Kavli Institute for Astrophysics and Space Research
Institute of Physics/American Astronomical Society
Ajello, M., P. Rebusco, N. Cappelluti, O. Reimer, H. Böhringer, J. Greiner, N. Gehrels, J. Tueller, and A. Moretti. “ GALAXY CLUSTERS IN THE SWIFT /BURST ALERT TELESCOPE ERA: HARD X-RAYS IN THE INTRACLUSTER MEDIUM .” The Astrophysical Journal 690, no. 1 (December 1, 2008): 367–388. © 2008 American Astronomical Society.
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