A search for outstanding sources of PeV cosmic rays: Cassiopeia A, the Crab Nebula, the Monogem Ring--But how about M33 and the Virgo cluster?

TL;DR

This study analyzes 1.4 million PeV cosmic ray air showers, identifying potential sources like supernova remnants, nearby galaxies, and galaxy clusters, suggesting some objects contribute significantly to cosmic ray flux.

Contribution

It introduces an iterative algorithm for analyzing cosmic ray arrival directions and finds correlations with known astrophysical objects, indicating their possible role as sources.

Findings

Zones with >3 sigma excess flux of cosmic rays identified

Significant coincidences with SNRs, pulsars, and star clusters found

Evidence of contributions from M33 galaxy and Virgo cluster to cosmic rays

Abstract

We study arrival directions of 1.4x10^6 extensive air showers (EAS) registered with the EAS--1000 Prototype Array in the energy range 0.1--10 PeV. By applying an iterative algorithm that provides uniform distribution of the data with respect to sidereal time and azimuthal angles, we find a number of zones with excessive flux of cosmic rays (CRs) at >=3 sigma level. We compare locations of the zones with positions of galactic supernova remnants (SNRs), pulsars, open star clusters, and regions of ionized hydrogen and find remarkable coincidences, which may witness in favour of the hypothesis that certain objects of these types, including the SNRs Cassiopeia A, the Crab Nebula, the Monogem Ring and some other, provide a noticeable contribution to the flux of CRs in the PeV range of energies. In addition, we find certain signs of a contribution from the M33 galaxy and a number of comparatively nearby groups of active galactic nuclei and interacting galaxies, in particular those in the Virgo cluster of galaxies. The results also provide some hints for a search of possible sources of ultra-high energy (UHE) cosmic rays and support an earlier idea that a part of both UHE and PeV CRs may originate from the same astrophysical objects.