Note on the Origin of the Highest Energy Cosmic Rays

TL;DR

This paper critiques a galactic magnetic field model used to interpret the origins of the highest energy cosmic rays, arguing it prevents source identification and challenges previous clustering interpretations.

Contribution

It provides a critical analysis of the galactic magnetic field model, showing it cannot reliably trace cosmic ray origins or identify point sources at ultra-high energies.

Findings

The model causes focusing of particles towards the North galactic pole.

Directional information from cosmic rays at energies up to 200 EeV is unreliable.

Clustering of cosmic rays does not imply point sources or link to M87.

Abstract

In this note we argue that the galactic model chosen by E.-J. Ahn, G. Medina-Tanco, P.L. Bierman and T. Stanev in their paper discussing the origin of the highest energy cosmic rays, is alone responsible for the focussing of positive particles towards the North galactic pole. We discuss the validity of this model, in particular in terms of field reversals and radial extensions. We conclude that with such a model one cannot retreive any directional information from the observed direction of the cosmic rays. In particular one cannot identify point sources at least up to energies of about 200 EeV. Therefore the apparent clustering of the back-traced highest energy cosmic rays observed to date cannot be interpreted as an evidence for a point source nor for the identification of M87, which happens to be close to the North pole, as being such a source.