Galaxy Clusters with the Fermi-LAT: Status and Implications for Cosmic Rays and Dark Matter Physics

TL;DR

This paper reviews the current status of galaxy cluster observations with the Fermi-LAT, discussing implications for cosmic rays and dark matter, highlighting the challenges in detecting gamma-ray emissions from these massive systems.

Contribution

It provides an update on Fermi-LAT observations of galaxy clusters and discusses the implications for cosmic ray and dark matter physics, emphasizing the current detection challenges.

Findings

No galaxy cluster has been detected in gamma rays yet.

Fermi-LAT observations constrain models of cosmic rays and dark matter in clusters.

The results inform future strategies for gamma-ray searches in galaxy clusters.

Abstract

Galaxy clusters are the most massive systems in the known universe. They host relativistic cosmic ray populations and are thought to be gravitationally bound by large amounts of Dark Matter, which under the right conditions could yield to a detectable $\gamma$-ray flux. Prior to the launch of the Fermi satellite, predictions were optimistic that Galaxy clusters would be established as $\gamma$-ray bright objects by observations through its prime instrument, the Large Area Telescope (LAT). Yet, despite numerous efforts, even a single cluster detection is still pending.