A Monte Carlo Bayesian Search for the Plausible Source of the Telescope Array Hotspot

TL;DR

This paper introduces a Monte Carlo Bayesian method to identify the likely source of the Telescope Array hotspot of ultrahigh-energy cosmic rays, supporting a single-source hypothesis with a 0.2% chance probability.

Contribution

The paper develops a novel Bayesian inference approach for source localization of cosmic rays, integrating magnetic deflections and applying it to TA hotspot data.

Findings

Hotspot distribution consistent with a single source

Chance probability of homogeneous origin is 0.2%

Method can infer source location and magnetic field parameters

Abstract

The Telescope Array (TA) collaboration has reported a hotspot of 19 ultrahigh-energy cosmic rays (UHECRs). Using a universal model with one source and energy-dependent magnetic deflections, we show that the distribution of the TA hotspot events is consistent with a single source hypothesis, although multiple sources cannot be ruled out. The chance probability of this distribution arising from a homogeneous distribution is $0.2\%$. We describe a Monte Carlo Bayesian (MCB) inference approach, which can be used to derive parameters of the magnetic fields as well as the source coordinates, and we apply this method to the TA hotspot data, inferring the location of the likely source. We discuss possible applications of the same approach to future data.