The Dynamics and Afterglow Radiation of Gamma-Ray Bursts

Andrew MacFadyen (NYU)

Gamma-ray bursts produce afterglow radiation as they drive strong
relativistic shocks into the surrounding medium. The explosion energy
is beamed into narrow jets which initially do not spread significantly
due to relativistic kinematics. As the shock decelerates, lateral
spreading ensues and the blastwave slowly transitions into a spherical
non-relativistic shock. I will discuss recent progress in
understanding the dynamics of this process, as well as the radiative
signatures received by observers at arbitrary angles with respect to
the jet axis. I will then discuss new relativistic MHD simulations of
turbulent amplification of magnetic field relevant for afterglow
radiation as well as for neutron star mergers. If time permits, I will
also briefly discuss very recent work on low-mass protoplanet
migration. These topics are connected by recent developments in
numerical hydrodynamics including the use of dynamical computational
meshes.