1. Interaction among cosmic Rays, waves and large scale turbulence Interaction among cosmic Rays, waves and large scale turbulence Huirong Yan Kavli Institute of Astronomy & Astrophysics, Peking U Collaboration: A. Lazarian (UW-Madison), R. Schlickeiser (U Ruhr-Bochum)

2. ImportanceImportance Propagation: Acceleration: CMB synchrotron foreground Diffuse ɣ ray emission diffuse Galactic 511 keV radiation Stochastic Acceleration: Fermi (49) Gamma ray burst Solar Flare

3. Big simulation itself is not adequate big numerical simulations fit results due to the existence of "knobs" of free parameters (see, e.g., http://galprop.stanford.e du/). http://galprop.stanford.e du Self-consistent picture can be only achieved on the basis of theory with solid theoretical foundations and numerically tested.

4. Compressible Turbulence dominates CR scattering Scattering frequency (Kolmogorov ) Alfven modes Big difference!!! (Chandran 2000) The often adopted Alfven modes are useless. Fast modes dominate CR scattering (Yan & Lazarian 02,04,08). eddies l||l|| ll modesmo des momodes Depends ondamping dam damping fast modes

5. CR Transport varies from place to place! Flat dependence of mean free path can occur due to collisionless damping ( Yan & Lazarian 2008 ). CR Transport in ISM Mean free path (pc) Kinetic energy halo WIM Text from Bieber et al 1994 Palmer consensus

6. Feedback of Cosmic Rays (CRs) on MHD turbulence Slab modes with Lazarian & Beresnyak 2006, Yan & Lazarian 2011

7. Gyroresonance Instability Turbulence compression Scattering by instability generated slab wave A β ≝ Pgas/P mag < 1, fast modes ( isotropic cascade +anisotropic damping ) β > 1 slow modes ( GS95 ) Wave Growth is limited by Nonlinear Suppression!

8. Scattering by growing waves Anisotropy cannot reach δv/v A, the value predicted earlier ( Lazarian & Beresnyak 2006 ), and the actual growth is slower and smaller amplitude due to nonlinear suppression ( Yan &Lazarian 2011 ). By balancing it with the rate of increase due to turbulence compression, we can get Bottle-neck of growth due to energy constraint: Simple estimates:

9. Gyroresonance instabiltiy of cosmic rays

10. domains for different regimes of CR scattering Damped by background turbulence λ fb cutoff due to linear damping

11. Hydronic picture of gamma ray emission near SNR Supernova remnant Text streaming CRs molecular clouds

12. Acceleration is limited by the wave growth at the shock front for MHD turbulence with k ⊥ >> k ||

13. maximum energy at a give epoch Maximum energy accelerated at a given shock radius is higher than the case when the background turbulence is assumed isotropic.

14. Accelerated CR flux and γ ray emission D<<D ISM

15. Result is self-consistent! Steaming instability due to increased CR flux is sufficient to overcome the damping by turbulence.

16. SummarySummary Compression by large scale turbulence results in anisotropic distribution of CRs, which induces gyroresonance instability. The growth of the instability is balanced by the feedback of the slab waves on the anisotropy of CRs. Small scale slab waves are generated in compressible turbulence by gyroresonance instability, dominating the scattering of low energy CRs (<100GeV). Feedback of CRs on turbulence should be included in future turbulence simulations. The flux of CRs near SNRs is increased enough to create strong streaming instability that can overcome the damping by background turbulence for the energy range considered. The enhanced scattering by the instability is enough to reproduce the observed gamma ray flux from molecular clouds. at the proximity of SNR. The enhanced scattering by the instability is enough to reproduce the observed gamma ray flux from molecular clouds. at the proximity of SNR. \item The enhanced scattering by the instability is enough to reproduce the observed gamma ray flux from molecular clouds at the proximity of SNR. The interaction of streaming instability and background turbulence determines the maximum energy of accelerated particles. For perpendicular transport: Perpendicular transport