AAS 197, January 2001
Session 107. Galaxy Clusters and Large Scale Structure II
Display, Thursday, January 11, 2001, 9:30-4:00pm, Exhibit Hall

[107.18] Simulations of High Energy Particle Acceleration During Cosmic Structure Formation

T. W. Jones (University of Minnesota), F. Miniati (University of Minnesota & Max-Planck-Institute for Astrophysics), D. Ryu (Chungnam National University), H. Kang (Pusan National University)

There is strong and growing interest in the properties of relativistic particles, or cosmic-rays, in clusters of galaxies. Those CRs may provide not only unique and vital diagnostic information through their emissions, but may influence cluster formation and dynamics as well as thermal ICM emissions if they constitute a dynamically significant component. We report here on initial results of simulations of cosmic structure formation that include for the first time explicit treatment of the acceleration and transport of CR protons and electrons. The calculations were done using an Eulerian TVD hydro + N-body cosmology code with passive magnetic fields and CRs. The CR treatment includes the effects of diffusive shock acceleration, plus adiabatic, radiative and Coulomb losses. Both protons and electrons are injected at shocks from the thermal plasma using an established model, while additional CR electrons and positrons result from decay of charged pions produced during inelastic collisions between CRs and thermal plasma.

The simulations suggest that structure'' shocks penetrate into clusters much more commonly than generally assumed, and that they are probably effective CR accelerators capable of producing CR pressures representing a significant fraction of the ICM gas pressure. Using the simulated cluster properties we have computed synthetic observations'' of their radio, nonthermal X-ray and \gamma-ray luminosity and brightness distributions as well as the SZ and Faraday rotation modifications of background radiations penetrating them. This work has been supported in the US by the NSF, NASA and the University of Minnesota Supercomputing Institute and in Korea by KOSEF.