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Francesco Miniati, T. W. Jones (University of Minnesota), D. Ryu (Chungnam National University), H. Kang (Pusan National University)
We have investigated in detail the properties of cosmic rays (CRs) accelerated by cosmic shock waves during structure formation in the universe. We show for the first time from numerical simulations of structure formation the expected spatial and spectral properties of CR electrons and protons inside these structures. Our simulations include explicitly both the magnetic field, diffusive acceleration of CRs and relevant energy losses. We have carried out synthetic observations of radiative emissions expected and present a comparison with some observational results and their implications.
Extremely complex shock structures have recently been revealed through accurate analysis of numerical simulation data (Miniati etal 1999a, b). Here we concentrate on these shocks as sites for efficient CR acceleration. This physics is now very relevant, since recent observational evidence shows the presence of energetically important CRs populating cosmic structures. In particular, relativistic CR electrons have been observed in galactic clusters (GCs) through EUV and hard X-ray synchrotron emission. A quantitative assessment suggests the need for cosmically recent particle acceleration there. These detections of CR electrons indirectly verify the existence of a substantial proton component as well. Some estimates of the latter accordingly suggest that they could provide a substantial fraction of the total pressure in GCs. That would be of great cosmological relevance. We will explore these issues in the light of our new simulation results.
This work is supported in part by the NSF, NASA and the University of Minnesota Supercomputing Institute.
The author(s) of this abstract have provided an email address for comments about the abstract: min@msi.umn.edu