2017/07/04 by Noémie Globus, Noemie Globus, Globus, Noemie +10 · 1 citation
Engineering · Physics and Astronomy · #Astrophysics and Cosmic Phenomena #Particle Accelerators and Free-Electron Lasers #Particle accelerators and beam dynamics #astro-ph.HE
paper · pdf · doi:10.48550/arxiv.1707.01177
8 pages, 3 figures, to appear in the Proceedings of the 35th International Cosmic Ray Conference 10-20 July, 2017 Bexco, Busan, Korea
arxiv created 2017/08/16 · arxiv updated 2017/08/17
The Telescope Array (TA) shows a 20∘ hotspot as well as an excess of UHECRs above 50~EeV when compared with the Auger spectrum. We consider the possibility that both the TA excess and hotspot are due to a dominant source in the Northern sky. We carry out detailed simulations of UHECR propagation in both the intergalactic medium and the Galaxy, using different values for the intergalactic magnetic field. We consider two general classes of sources: transients and steady, adopting a mixed UHECR composition that is consistent with the one found by Auger. The spatial location of the sources is draw randomly. We generate Auger-like and TA-like data sets from which we determine the spectrum, the sky maps and the level of anisotropy. We find that, while steady sources are favored over transients, it is unlikely to account for all the currently available observational data. While we reproduce fairly well the Auger spectrum for the vast majority of the simulated data sets, most of the simulated data sets with a spectrum compatible with that of TA (at most a few percent depending on density model tested) show a much stronger anisotropy than the one observed. We find that the rare cases in which both the spectrum and the anisotropy are consistent require a steady source within ∼ 10 Mpc, to account for the flux excess, and a strong extragalactic magnetic field ∼ 10 nG, to reduce the excessive anisotropy.