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Midwest Magnetic Field 2011

Motivation Theory Results Discussion. Acceleration of Cosmic-rays by Super- Alfvenic turbulence. Hyeseung Lee University of Wisconsin-Madison Alex Lazarian University of Wisconsin-Madison Reinhard Schlikeiser University of Bochum, Germany. Midwest Magnetic Field 2011. Motivation

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Midwest Magnetic Field 2011

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  1. Motivation Theory Results Discussion Acceleration of Cosmic-rays by Super-Alfvenic turbulence Hyeseung Lee University of Wisconsin-Madison Alex Lazarian University of Wisconsin-Madison ReinhardSchlikeiser University of Bochum, Germany Midwest Magnetic Field 2011

  2. Motivation Theory Results Discussion Cosmic Ray Galaxy Cluster Cosmic Ray Spectrum 1GeV ~ Knee : Galactic Origin (Supernovae) Slope ϒ=-2.7 Knee ~ Ankle : Larger Shocks (Galactic wind - Neutron Stars, Superbubbles, Reaccelerated heavy nuclei) and SN explosions into stellar winds Slope ϒ=-3.1 Slope ϒ=-2.7 UHECR (Ultra High Energy Cosmic rays) Viktor Hess(1912) Midwest Magnetic Field 2011

  3. Motivation Theory Results Discussion Galaxy Cluster Hillas Plot rlar < L It need astrophysical acceleration mechanism UHECR (Ultra High Energy Cosmic rays) Extragalactic (GRB, AGN, Galaxy Cluster) Midwest Magnetic Field 2011

  4. Motivation Theory Results Discussion Stochastic Acceleration Second-order Fermi Acceleration Fermi(1949) Galactic CRs are accelerated as the result of many collision with massive, magnetized cloud Particle in head-on collisions  gains energy Particle in an overtaking collisions  loses energy Stochastic Acceleration by MHD turbulence But, head-on collisions are more frequent On average, net energy gain θexit : <cosθout’> = 0 θenter: ν - Vcosθin Midwest Magnetic Field 2011

  5. Motivation Theory Results Discussion Acceleration by MHD turbulence Property of MHD Turbulence Sub-Alfvenic turbulence ( Vl < VA ) (Cho & Lazarian 2006) Super-Alfvenic turbulence ( Vl > VA ) Super-Alfvenic turbulence evolves along the hydrodynamic isotropic Kolmogorov cascade The acceleration by sub-Alfvenic turbulence had been discussed by Cho & Lazarian 2006. Assume that compression follows Kolmogorov scaling Goldreich-Sridhar 95 scaling For example : ISOTROPIC Cho & Larzarin (2002) Midwest Magnetic Field 2011

  6. Motivation Theory Results Discussion MHD turbulence Diffuse by MHD turbulence Midwest Magnetic Field 2011

  7. Motivation Theory Results Discussion MHD turbulence Diffuse by MHD turbulence Midwest Magnetic Field 2011

  8. Motivation Theory Results Discussion MHD turbulence Diffuse by MHD turbulence Midwest Magnetic Field 2011

  9. Motivation Theory Results Discussion MHD turbulence Diffuse by MHD turbulence Midwest Magnetic Field 2011

  10. Motivation Theory Results Discussion MHD turbulence Comparison of D The acceleration by large-scale turbulence is relative to the momentum diffusion coefficient For super-alfvenic turbulence, Large-Scale motion dominates acceleration of cosmic- ray !!! Midwest Magnetic Field 2011

  11. Motivation Theory Results Summary SUMMARY Super-Alfvenic turbulence is present in astrophysicsal environment : galaxy clusters 2. For super-Alfvenic acceleration by large scale motions dominates resonance scattering. 3. The acceleration by super-Alfvenic turbulence should be taken into account in models for galaxy cluster and molecular cloud. Midwest Magnetic Field 2011

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