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Probing the Cosmic Ray Population of the Giant Elliptical Galaxy M 87 with Observed TeV Gamma-Rays

Christoph Pfrommer·Torsten A. Ensslin
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Abstract

We examine the cosmic ray proton (CRp) population within the giant elliptical galaxy M 87 using the TeV gamma-ray detection of the HEGRA collaboration. In our scenario, the gamma-rays are produced by decaying pions which result from hadronic CRp interactions with thermal gas of the interstellar medium of M 87. By comparing the gamma-ray emission to upper limits of EGRET, we constrain the spectral index of the CRp population to alpha(GeV,TeV) < 2.275 within our scenario. Both the expected radial gamma-ray profile and the required amount of CRp support this hadronic scenario. The accompanying radio mini-halo of hadronically originating cosmic ray electrons is outshone by the synchrotron emission of the relativistic jet of M 87 by one order of magnitude. According to our predictions, the future GLAST mission should allow us to test this hadronic scenario.

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Christoph Pfrommer, Torsten A. Ensslin. 2003-07-17. Probing the Cosmic Ray Population of the Giant Elliptical Galaxy M 87 with Observed TeV Gamma-Rays. https://doi.org/10.1051/0004-6361%3A20031088

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