Speaker
Description
Ultra high energy cosmic rays are charged particles originating from various astrophysical sources and they exhibit anisotropic distributions in their arrival directions at Earth. Several studies have been conducted by the Pierre Auger Observatory on the arrival directions of such particles by employing a likelihood analysis which showed that the starburst galaxies (SBG) model have a better agreement than the hypothesis of isotropy with a 4$\sigma$ significance. Although in these analysis the role of the galactic magnetic field (GMF) has not been considered. The GMF is expected to play a key role in the arrival direction of charged particles and understanding its role in shaping these anisotropies is of great importance in grasping the mechanisms governing cosmic ray propagation and their sources.
To address this, we created simulated datasets based on the SBG catalog on which we conducted the likelihood analysis employed by the Pierre Auger Collaboration. The datasets have been constructed by adding an isotropic background to the signal events which have been generated with CRPropa3. The model by Jansson & Farrar (JF12) has been employed as the GMF and a lens has been created to apply its effects to the simulated events.
Our analysis revealed that in 20% of the simulated datasets, it was possible to recover a compatible set of best-fit parameters. However, it was noted that the true anisotropy fraction needed to be increased due to the effect that the elements which dominate the spectrum at high energy are highly isotropized.
