Cosmic Rays in the Large-Scale Structure of the Universe

Abstract

Like in our galaxy, cosmic rays (CRs) are expected to exist in the space between galaxies. Shocks waves induced during the hierarchical formation of the large-scale structure of the universe, which are collisionless like most astrophysical shocks, are believed to be dominant sources of those intergalactic CRs. Here, based on N-body/hydrodynamic simulations of a LCDM universe, I present the nature and origin of intergalactic shock waves in the context of the large-scale structure formation, with an emphasis on those in clusters of galaxies. And then, using PIC and diffusive shock acceleration simulation data, I describe the energy and spectrum of the CRs accelerated at the intergalactic shock waves. I finally discuss the status of the observations of CRs in clusters of galaxies.