The structure of colissionless shocks
 
Collisionless shocks are ubiquitous in astrophysical environments where supersonic motions in tenuous plasma are common. These shocks are seen on all scales, ranging from the interplanetary space in our solar system to accretion shocks on cosmological scales. Collisionless shocks are believed to be the main cosmic particle accelerators, generating the high energy cosmic rays observed on Earth. Being collisionless, the interaction in these shocks is provided by collective electromagnetic plasma processes. Thus, the structure of collisionless shocks depend on their magnetization level and plasma content (ion-electrons, pairs, etc.). Our study focuses on the structure of relativistic unmagnetized or weakly magnetized shocks. This field is flourishing in recent years due to new numerical simulations, that for the first time, are able to obtain shocks, accelerate particles and generate strong magnetic fields. Nevertheless, these simulations are still far from reaching steady state or from covering the entire scale range that is relevant for astrophysical shocks. We examine, mostly analytically with the guidance of specially designed numerical simulations, various processes that are likely to play an important role in the final non-linear structure of such shock.
 
Growth rate of two-stream-like
modes (Nakar et al., 2011)
Recent publications Nakar, E., Bret, A. & Milosavljević, M. (2011), Two-stream-like Instability in Dilute Hot Relativistic Beams and Astrophysical Relativistic Shocks, ApJ, 738, 93 Couch, S., Milosavljević, M. & Nakar, E. (2008), Shock Vorticity Generation from Accelerated Ion Streaming in the Precursor of Ultrarelativistic Gamma-Ray Burst External Shocks, ApJ, 688, 462 http://adsabs.harvard.edu/abs/2011ApJ...738...93Nhttp://adsabs.harvard.edu/abs/2008ApJ...688..462Cshapeimage_3_link_0shapeimage_3_link_1