Volume 484 - 7th International Symposium on Ultra High Energy Cosmic Rays (UHECR2024) - session Posters
Correlation studies on UHECR arrival direction and source candidates, with a convolution of magnetic field and mass composition
R. Higuchi* and  for the TA collaboration
*: corresponding author
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Pre-published on: March 21, 2025
Published on: —
Abstract
Several studies reported the correlation between the arrival directions of ultra-high-energy cosmic rays (UHECRs) and nearby starburst galaxies (SBGs). Auger collaboration (2018, 2022) reported a $\sim 4 \sigma$ significance correlation with SBGs, and the Telescope Array (TA) experiment also showed consistent results (TA collaboration 2018).
Considering 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 the TA and Auger experiments with nearby SBGs. In the analysis, we changed the UHECR flux model from SBGs based on three assumptions: (1) the same flux model as in the Auger collaboration (2022), (2) distance dependence of scattering angle 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 developed 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 confirmed 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 report, we report the current status of our analysis and discuss the model dependence.
DOI: https://doi.org/10.22323/1.484.0093
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