Princeton University Astroplasmas Seminar

Galaxy clusters undergoing mergers host spectacular megaparsec-scale, highly polarized diffuse radio emission known as radio relics. With their enormous extent, these sources trace the largest particle accelerators in the Universe. Relics are usually found at the cluster outskirts and illuminated by relativistic electrons accelerated by merger-driven shock fronts in the intracluster medium (ICM). However, the currently proposed particle acceleration mechanisms are not efficient enough to accelerate particles from the thermal pool of the ICM. There is increasing observational evidence that requires us to consider the unknown acceleration processes across the entire lifetime of clusters, not only in the proximity of large merger events. The new generation of radio telescopes permits wideband spectro-polarimetric radio observations with unprecedented sensitivity and spatial resolution, thus allowing the investigation of the finest details. In this talk, I will discuss recent results obtained with high-resolution radio observations of some well-known relics. These findings challenge our understanding of particle acceleration mechanisms in galaxy clusters and highlight the need for additional theoretical work to uncover the underlying physics.