Speakers
Description
There's a reported correlation between the arrival directions of ultra-high-energy cosmic rays (UHECRs) and nearby starburst galaxies (SBGs). Auger collaboration (2018, 2022) reported a ~4 sigma significance correlation with SBGs, and the Telescope Array (TA) experiment also shows consistent results (TA collaboration 2018). The effects of the magnetic field on UHECR flux would be mandatory to constrain the UHECR source population. We re-investigate the correlation of UHECR arrival direction obtained by TA and Auger experiments with nearby SBGs. In the analysis, we change the UHECR flux model from SBGs based on three assumptions: (1) the same flux model as in the Auger collaboration (2022), (2) scattering by a turbulent extra-galactic magnetic field, (3) deflection and scattering by the galactic magnetic (GMF) field. For the estimation of the effects of the galactic magnetic (GMF) field, we develop the method to calculate the log-likelihood with the GMF model (Jansson and Farrar 2012ab) and mass composition model (global-spline fit, Dembinski et al. 2017). We confirm less than 2 and 4 sigma global significance for TA and Auger experiments, respectively. The assumption of scattering by a turbulent extra-galactic magnetic field does not change the significance with order. The current result with GMF is sensitive to mass-composition assumption. In this talk, we report the current status of our analysis and discuss the model dependence.
