Early evolution of spherical ejecta expanding into the circumstellar matter at ultra-relativistic speeds

TL;DR

This paper introduces a new self-similar model for the early stages of ultra-relativistic spherical ejecta expanding into circumstellar matter, capturing shock dynamics and ejecta behavior.

Contribution

It provides a novel analytical solution describing the initial evolution of ultra-relativistic ejecta interacting with circumstellar matter.

Findings

Derivation of a self-similar solution for ultra-relativistic ejecta expansion.

Characterization of shock wave propagation in circumstellar matter.

Insight into the weak discontinuity within the ejecta at sound speed.

Abstract

We present a new self-similar solution describing early evolution of an ultra-relativistic flow resulting from a collision of homologously expanding spherical ejecta with the circumstellar matter, in which a shock wave propagates in the circumstellar matter while a weak discontinuity propagates in the ejecta at the sound speed