Effects of galactic magnetic field on the UHECR correlation studies with starburst galaxies

Abstract

We estimate the biases caused by the coherent deflection of cosmic rays due to the Galactic magnetic field (GMF) in maximum-likelihood analysis for searches of ultrahigh-energy cosmic ray (UHECR) sources in the literature. We simulate mock event datasets with a set of assumptions for the starburst galaxy (SBG) source model (arXiv:1801.06160), coherent deflection by a GMF model (arXiv:1204.3662,arXiv:1210.7820), and mixed-mass composition (arXiv:1901.03338); 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 $f_{\mathrm{ani}}$ is estimated systematically lower than the true value. We estimate the true parameters which are compatible with the best-fit parameters reported in (arXiv:1801.06160), and find that except for a narrow region with a large anisotropic fraction and small separation angular scale a wide parameter space is still compatible with the experimental results. We also develop a maximum-likelihood method that takes into account the GMF model and confirm in the MC simulations that we can estimate the true parameters within a 1$\sigma$ contour under the ideal condition that we know the event-by-event mass and the GMF.

References in corpus (23)

• The Pierre Auger Cosmic Ray Observatory
• Correlation of the highest energy cosmic rays with nearby extragalactic objects
• A New Model of the Galactic Magnetic Field
• Indications of Intermediate-Scale Anisotropy of Cosmic Rays with Energy Greater Than 57 EeV in the Northern Sky Measured with the Surface Detector of the Telescope Array Experiment
• Combined fit of spectrum and composition data as measured by the Pierre Auger Observatory
• Update on the correlation of the highest energy cosmic rays with nearby extragalactic matter
• The Galactic Magnetic Field
• CRPropa 3 - a Public Astrophysical Simulation Framework for Propagating Extraterrestrial Ultra-High Energy Particles
• Deriving global structure of the Galactic Magnetic Field from Faraday Rotation Measures of extragalactic sources
• Indication of anisotropy in arrival directions of ultra-high-energy cosmic rays through comparison to the flux pattern of extragalactic gamma-ray sources
• Searches for Anisotropies in the Arrival Directions of the Highest Energy Cosmic Rays Detected by the Pierre Auger Observatory
• Cosmic Ray Anisotropy Analysis with a Full-Sky Observatory
• Ultra-High-Energy Cosmic Rays
• A new view on Auger data and cosmogenic neutrinos in light of different nuclear disintegration and air-shower models
• AugerPrime: the Pierre Auger Observatory Upgrade
• IMAGINE: A comprehensive view of the interstellar medium, Galactic magnetic fields and cosmic rays
• Large scale distribution of arrival directions of cosmic rays detected above $10^{18}$ eV at the Pierre Auger Observatory
• Testing a reported correlation between arrival directions of ultrahigh-energy cosmic rays and a flux pattern from nearby starburst galaxies using Telescope Array data
• Mapping UHECRs deflections through the turbulent galactic magnetic field with the latest RM data
• A Monte Carlo Bayesian Search for the Plausible Source of the Telescope Array Hotspot
• An upper limit on the strength of the extragalactic magnetic field from ultra-high-energy cosmic-ray anisotropy
• GCOS -- The Global Cosmic Ray Observatory
• Surface detectors of the TAx4 experiment

Cited by in corpus (1)

• Insights on the mass composition of ultrahigh-energy cosmic rays from small-scale anisotropy with large-scale structure simulations