Evidence for the Sombrero Galaxy as an Accelerator of the Highest-Energy Cosmic Rays

TL;DR

This study presents evidence linking the Sombrero galaxy to the origin of the highest-energy cosmic rays, suggesting active supermassive black holes as their accelerators based on 17 years of observational data.

Contribution

It provides the first significant spatial association between a specific galaxy and ultrahigh-energy cosmic rays, supporting black holes as their potential sources.

Findings

Significant association between cosmic ray multiplet and the Sombrero galaxy.

Detection of a multiplet of 25.7 cosmic rays with >4.5 sigma significance.

Evidence supporting active supermassive black holes as cosmic ray sources.

Abstract

Ultrahigh-energy cosmic rays (UHECRs) are the highest energy messenger from space, with energies exceeding 1 EeV. Although UHECRs were discovered over 60 years ago, their origin still remains a mystery. Pinpointing sources of UHECRs is crucial for understanding the extreme astrophysical processes that accelerate particles to such extraordinary energies. We searched for UHECR multiplets via analyzing 17 years of data with energies greater than 40 EeV from the Pierre Auger Observatory. A spatial association is found between a multiplet of $25.7^{+6.2}_{-7.0}$ cosmic rays and the Sombrero galaxy with a local (global) significance of $4.5~\sigma~(3.3~\sigma)$. The Sombrero galaxy hosts a supermassive central black hole with a mass of $\sim1\times 10^9 M_{\odot}$ and exhibits large-scale radio lobes and jets. Our finding provides critical evidence on active supermassive black holes as the source of the highest-energy cosmic rays.