Prof Subir Sarkar

Abstract:

As ultra-high energy cosmic ray protons propagate through the universe, they undergo photo-meson interactions with the cosmic microwave background, generating the 'cosmogenic' neutrino flux. If, however, a substantial fraction of the cosmic ray primaries are heavy nuclei rather than protons, they would preferentially lose energy through photo-disintegration so the corresponding neutrino flux may be substantially depleted. We investigate this issue using a Monte Carlo simulation of cosmic ray propagation through intragalactic radiation fields and assess the impact of the altered neutrino fluxes on next-generation neutrino telescopes. © 2004 Elsevier B.V. All rights reserved.

Abstract:

Two ground-based experiments have recently independently detected TeV γ-rays from the direction of the galactic centre. The observations made by the VERITAS and CANGAROO collaborations are unexpected, although not impossible to interpret in terms of astrophysical sources. Here we examine in detail whether the observed γ-rays may arise from the more exotic alternative of annihilations of dark matter particles clustered in the centre of the galaxy. ©2004 IOP Publishing Ltd.