Hydrodynamical interaction of mildly relativistic ejecta with an ambient medium

Understand

Hydrodynamical interaction of spherical ejecta freely expanding at mildly relativistic speeds into an ambient cold medium is studied in semi-analytical and numerical ways to investigate how ejecta produced in energetic stellar explosions dissipate their kinetic energy through the interaction with the surrounding medium.

• We especially focus on the case in which the circumstellar medium is well represented by a steady wind at a constant mass-loss rate having been ejected from the stellar surface prior to the explosion.
• As a result of the hydrodynamical interaction, the ejecta and circumstellar medium are swept by the reverse and forward shocks, leading to the formation of a geometrically thin shell.
• We present a semi-analytical model describing the dynamical evolution of the shell and compare the results with numerical simulations.