Numerical Simulations of Low-Luminosity Gamma Ray Bursts

We have employed RENZO, an adaptive mesh refinement relativistic hydrodynamics code, to study the propagation of a mildly relativistic low-power jet through the progenitor star, the effect of dense circumstellar material on jet propagation, and the transition from a collimated to a spherical outflow. This investigation is still in progress; here, we present preliminary results. 1. Propagation of a low power jet • A high luminosity engine produces a jet that punches through the star, while at lower power the jet can be choked off, driving a spherical explosion instead. • A low power jet requires a narrow opening angle to successfully penetrate the star 2. Effect of dense circumstellar material • Placing a sufficiently dense wind around the star can significantly affect the jet’s breakout and subsequent propagation outside the star. 3. Effects at large scales • At later times, the jet becomes uncollimated, ultimately transitioning to a spherical outflo