1. Effects of the Galactic Magnetic Field on the UHECR Correlation Studies with Starburst Galaxies
- Author
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Ryo Higuchi, Takashi Sako, Toshihiro Fujii, Kazumasa Kawata, and Eiji Kido
- Subjects
Cosmic ray astronomy ,Cosmic ray sources ,Cosmic rays ,Ultra-high-energy cosmic radiation ,Astrophysics ,QB460-466 - Abstract
We estimate the biases caused by the coherent deflection of cosmic rays due to the Galactic magnetic field (GMF) in maximum likelihood analyses for searches of ultrahigh-energy cosmic-ray sources in the literature. We simulate mock event data sets with a set of assumptions for the starburst galaxy source model, coherent deflection by a GMF model, and mixed-mass composition. We then conduct a maximum likelihood analysis without accounting for the GMF in the same manner as previous studies. We find that the anisotropic fraction f _ani is estimated to be systematically lower than the true value. We estimate the true parameters that are compatible with the best-fit parameters that were reported, and find that except for a narrow region with a large anisotropic fraction and a small separation angular scale, a wide parameter space is still compatible with the experimental results. We also develop a maximum likelihood method that takes the GMF model into account and confirm in Monte Carlo simulations that we can estimate the true parameters within a 1 σ contour under the ideal condition that we know the event-by-event mass and the GMF.
- Published
- 2023
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