Neutrinos and Gamma Rays from Galaxy Clusters

TL;DR

This paper explores the potential detection of high-energy neutrinos and gamma rays from galaxy clusters, linking recent mergers and gamma-ray emissions to cosmic ray interactions, and estimates detection rates for upcoming observatories.

Contribution

It assesses the prospects of detecting neutrinos and gamma rays from specific galaxy clusters, highlighting their connection to recent mergers and gamma-ray emissions, and provides estimated detection rates for ICECUBE and Auger.

Findings

Potential detection of up to 0.3 neutrinos per year from Coma by ICECUBE.

Possible detection of a few gamma-ray events per year from Abell clusters by Auger.

Correlation between radio and gamma-ray fluxes supports cluster gamma-ray emission hypothesis.

Abstract

The next generation of neutrino and gamma-ray detectors should provide new insights into the creation and propagation of high-energy protons within galaxy clusters, probing both the particle physics of cosmic rays interacting with the background medium and the mechanisms for high-energy particle production within the cluster. In this paper we examine the possible detection of gamma-rays (via the GLAST satellite) and neutrinos (via the ICECUBE and Auger experiments) from the Coma cluster of galaxies, as well as for the gamma-ray bright clusters Abell 85, 1758, and 1914. These three were selected from their possible association with unidentified EGRET sources, so it is not yet entirely certain that their gamma-rays are indeed produced diffusively within the intracluster medium, as opposed to AGNs. It is not obvious why these inconspicuous Abell-clusters should be the first to be seen in gamma-rays, but a possible reason is that all of them show direct evidence of recent or ongoing mergers. Their identification with the EGRET gamma-ray sources is also supported by the close correlation between their radio and (purported) gamma-ray fluxes. Under favorable conditions (including a proton spectral index of 2.5 in the case of Abell 85, and sim 2.3 for Coma, and Abell 1758 and 1914), we expect ICECUBE to make as many as 0.3 neutrino detections per year from the Coma cluster of galaxies, and as many as a few per year from the Abell clusters 85, 1758, and 1914. Also, Auger may detect as many as 2 events per decade at ~ EeV energies from these gamma-ray bright clusters.