A Method for Constraining Cosmic Magnetic Field Models Using Ultra-High Energy Cosmic Rays: The Field Scan Method

TL;DR

This paper introduces a novel method to evaluate the consistency of cosmic magnetic field models with ultra-high energy cosmic ray data by comparing backtracked directions to isotropic simulations.

Contribution

It presents a new self-consistency method for testing cosmic magnetic field models against observed ultra-high energy cosmic ray data.

Findings

Method effectively distinguishes between different magnetic field hypotheses.

Provides a statistical framework for assessing cosmic ray source correlations.

Enhances understanding of galactic magnetic field influence on cosmic rays.

Abstract

The Galactic magnetic field, locally observed to be on the order of a few $\mu$G, is sufficiently strong to induce deflections in the arrival directions of ultra-high energy cosmic rays. We present a method that establishes measures of self-consistency for hypothesis sets comprised of cosmic magnetic field models and ultra-high energy cosmic ray composition and source distributions. The method uses two independent procedures to compare the backtracked velocity vectors outside the magnetic field model to the distribution of backtracked velocity directions of many isotropic observations with the same primary energies. This allows for an estimate of the statistical consistency between the observed data and simulated isotropic observations. Inconsistency with the isotropic expectation of source correlation in both procedures is interpreted as the hypothesis set providing a self-consistent description of GMF and UHECR properties for the cosmic ray observations.