MAGIC Gamma-ray Telescope Observation of the Perseus Cluster of Galaxies: implications for cosmic rays, dark matter, and NGC1275 - Astrophysics > High Energy Astrophysical PhenomenaReport as inadecuate




MAGIC Gamma-ray Telescope Observation of the Perseus Cluster of Galaxies: implications for cosmic rays, dark matter, and NGC1275 - Astrophysics > High Energy Astrophysical Phenomena - Download this document for free, or read online. Document in PDF available to download.

Abstract: The Perseus galaxy cluster was observed by the MAGIC Cherenkov telescope fora total effective time of 24.4 hr during 2008 November and December. Theresulting upper limits on the gamma-ray emission above 100 GeV are in the rangeof 4.6 to 7.5 x 10^{-12} cm^{-2} s^{-1} for spectral indices from -1.5 to -2.5,thereby constraining the emission produced by cosmic rays, dark matterannihilations, and the central radio galaxy NGC1275. Results are compatiblewith cosmological cluster simulations for the cosmic-ray-induced gamma-rayemission, constraining the average cosmic ray-to-thermal pressure to <4% forthe cluster core region <8% for the entire cluster. Using simplifiedassumptions adopted in earlier work a power-law spectrum with an index of-2.1, constant cosmic ray-to-thermal pressure for the peripheral clusterregions while accounting for the adiabatic contraction during the cooling flowformation, we would limit the ratio of cosmic ray-to-thermal energy toE CR-E th<3%. The upper limit also translates into a level of gamma-rayemission from possible annihilations of the cluster dark matter the dominantmass component that is consistent with boost factors of ~10^4 for thetypically expected dark matter annihilation-induced emission. Finally, theupper limits obtained for the gamma-ray emission of the central radio galaxyNGC1275 are consistent with the recent detection by the Fermi-LAT satellite.Due to the extremely large Doppler factors required for the jet, a one-zonesynchrotron self-Compton model is implausible in this case. We reproduce theobserved spectral energy density by using the structured jet spine-layermodel which has previously been adopted to explain the high-energy emission ofradio galaxies.



Author: The MAGIC Collaboration: J. Aleksić 1, L. A. Antonelli 2, P. Antoranz 3, M. Backes 4, C. Baixeras 5, S. Balestra 3, J. A. Barrio

Source: https://arxiv.org/



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