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19.05.2023 / 10:00 / Zeuthen, Zoom
Astroparticle SeminarGiant Cosmic-Ray Halos around M31 and the Milky Way
Sarah Recchia | Torino University
In recent years, a diffuse emission of 1–100 GeV gamma-rays has been detected from the direction of M31, extending up to 200 kpc from its center. The interpretation of such extended emission by the escape of cosmic rays produced in the galactic disk or in the galactic center is problematic and alternative explanations involving dark matter as a possible source have been proposed in the lite-rature. Here we provide a critical evaluation of a possible cosmic-ray origin (either leptonic or hadronic) of the gamma-ray emission in the frame-work of nonstandard cosmic-ray propagation scenarios or in the case of in situ particle acceleration in the galaxy’s halo. Correspondingly, the halo is powered by the galaxy’s nuclear activity or by the accretion of intergalactic gas. Intriguingly, if the formation of cosmic-ray halos around galaxies is a common phenomenon, the inter-actions of cosmic-ray protons and nuclei with the circumgalactic gas surrounding the Milky Way could be responsible for the isotropic diffuse flux of neutrinos observed by IceCube.
More Information: https://confluence.desy.de/display/DESYAstroparticlePublic/Astroparticle+Seminar
