Acceleration of CR at Large Scale Shocks and Their Cosmological Role for   Structure Formation in the Universe
  We investigate the dynamical importance of a newly recognized possible source of significant feedback generated during structure formation; namely cosmic ray (CR) pressure. We present evidence for the existence of numerous shocks in the hot gas of galaxy clusters (GCs). We employ for the first time an explicit numerical treatment of CR acceleration and transport in hydro simulations of structure formation. According to our results, CRs provide an important fraction of the total pressure inside GCs, up to several tenths. This was true even at high redshift (z=2), meaning that such non-thermal component could affect the evolution of structure formation. 
Francesco Miniati (1), Dongsu Ryu (2), T. W. Jones (1), Hyesung Kang   (3) ((1) University of Minnesota, (2) Chungnam Nation...