Jul 12 – 23, 2021
Europe/Berlin timezone

Effects of Galactic magnetic field on the UHECR anisotropy studies

Jul 15, 2021, 12:00 PM
1h 30m


Talk CRI | Cosmic Ray Indirect Discussion


Ryo Higuchi


Telescope Array (TA) and Auger experiments reported anisotropies in the arrival direction of ultra-high-energy cosmic rays (UHECRs). In particular, Auger reported a correlation between UHECR events and the flux model of assumed sources, and suggested a contribution of starburst galaxies (SBGs) to the anisotropy of UHECRs. However, they did not take into account the effect of coherent deflections by the galactic magnetic field (GMF) and the consequent effects of the energy spectrum and mass composition. In this study, we investigated the effect of the GMF on the arrival directions of UHECRs using the cosmic ray propagation code CRPropa3. We used a backtracking technique which consists in propagating antiparticles from the Earth. We analyzed the reported anisotropies, namely, the hot spot by TA and the SBG correlation by Auger, and found that the effect of GMF is small with pure proton assumption. By building a forward-tracking-function based on the backtracking calculation, we constructed a new method of calculating the flux model of sources with a convolution of GMF, energy spectrum and mass composition. We studied the source models of UHECRs that can be verified at high significance with the upcoming TAx4 data.


"Cosmic Ray","Galactic Magnetic Field"

Collaboration Telescope Array
Subcategory Experimental Results

Primary author


Dr Takashi Sako (ICRR, University of Tokyo) Kazumasa Kawata Toshihiro Fujii (Hakubi Center for Advanced Research, Kyoto University) Eiji Kido (RIKEN)

Presentation materials