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Galaxy clusters might be sources of TeV gamma rays emitted by high-energy protons and electrons accelerated by large scale structure formation shocks, galactic winds, or active galactic nuclei. Furthermore, gamma rays may be produced in dark matter particle annihilation processes at the cluster cores. We report on observations of the galaxy clusters Perseus and Abell 2029 using the 10 m Whipple Cherenkov telescope during the 2003-2004 and 2004-2005 observing seasons. We apply a two-dimensional analysis technique to scrutinize the clusters for TeV emission. In this paper we first determine flux upper limits on TeV gamma-ray emission from point sources within the clusters. Second, we derive upper limits on the extended cluster emission. We subsequently compare the flux upper limits with EGRET upper limits at 100 MeV and theoretical models. Assuming that the gamma-ray surface brightness profile mimics that of the thermal X-ray emission and that the spectrum of cluster cosmic rays extends all the way from thermal energies to multi-TeV energies with a differential spectral index of -2.1, our results imply that the cosmic ray proton energy density is less than 7.9% of the thermal energy density for the Perseus cluster.
We present Suzaku observations of the galaxy cluster Abell 2029, which exploit Suzakus low particle background to probe the ICM to radii beyond those possible with previous observations (reaching out to the virial radius), and with better azimuthal c
Abell 2029 is one of the most studied clusters due to its proximity (z=0.07), its strong X-ray brightness and its giant cD galaxy which is one of the biggest stellar aggregates we know. We present here the first weak lensing mass reconstruction of th
Galaxy cluster mergers are a powerful laboratory for testing cosmological and astrophysical models. However, interpreting individual merging clusters depends crucially on their merger configuration, defined by the masses, velocities, impact parameter
A recent study has presented marginal statistical evidence that gamma-ray burst sources are correlated with Abell clusters, based on analyses of bursts in the BATSE 3B catalog. Using precise localization information from the 3rd Interplanetary Networ
Recent Chandra and XMM X-ray observations of rich clusters of galaxies have shown that the amount of hot gas which is cooling below ~1 keV is generally more modest than previous estimates. Yet, the real level of the cooling flows, if any, remains to