A minimal width of the arrival direction distribution of ultra-high energy cosmic rays detected with the Yakutsk array

TL;DR

This study analyzes the arrival directions of ultra-high energy cosmic rays detected over several decades, finding significant anisotropy likely due to cosmic ray sources, using a novel minimal width distribution method.

Contribution

The paper introduces a new analysis method based on minimal width distributions to detect anisotropy in cosmic ray arrival directions.

Findings

Isotropy hypothesis rejected at 99.5% significance

Decreased minimal width suggests cosmic ray sources in specific regions

Results support presence of anisotropic sources at ultra-high energies

Abstract

This paper presents the results of searches for anisotropy in arrival directions of ultra-high energy cosmic rays detected with the Yakutsk Array during the 1974--2008 observational period together with available data from other giant extensive air shower arrays working at present. A method of analysis based on a comparison of the minimal width of distributions in equatorial coordinates is applied. As a result, a hypothesis of isotropy in arrival directions is rejected at the $99.5\%$ significance level. The observed decrease in the minimal width of distribution can be explained by the presence of cosmic ray sources in energy intervals and sky regions according to the recent indications inferred from data of the Yakutsk Array and Telescope Array experiments.