Simulation Studies of Early Afterglows Observed with SWIFT

We have applied numerical simulations and modeling to the particle acceleration, magnetic field generation, and emission from relativistic shocks and plan to compare them with the observed gamma‐ray burst emission. In collisionless shocks, plasma waves and their associated instabilities (e.g., the Weibel, Buneman and other two‐stream instabilities) are responsible for particle (electron, positron, and ion) acceleration and magnetic field generation. A 3‐D relativistic electromagnetic particle (REMP) code is used to study shock processes including spatial and temporal evolution of shocks in unmagnetized electron‐positron plasmas with three different jet velocity distributions. The “jitter” radiation from the shocks is different from synchrotron radiation. The dynamics of shock microscopic process evolution may provide some insight into early afterglows. Our simulation studies provide insight into new GRB observations with Swift.