Jets as diagnostics of the circumstellar medium and the explosion energetics of supernovae: the case of Cas A

TL;DR

This study uses hydrodynamical models to analyze the jets and circumstellar medium of Cas A, revealing that a short Wolf-Rayet phase is necessary to preserve the observed jet structures and estimating a lower limit for jet energy.

Contribution

The paper introduces detailed hydrodynamical models incorporating progenitor wind evolution to constrain the Wolf-Rayet phase duration and jet energy in Cas A.

Findings

Jet is destroyed if the Wolf-Rayet phase is long and a massive shell forms.

The Wolf-Rayet phase in Cas A's progenitor was likely short, a few thousand years.

Lower limit for jet energy in Cas A is approximately 10^{48} erg.

Abstract

We present hydrodynamical models for the Cassiopeia A (Cas A) supernova remnant and its observed jet / counter-jet system. We include the evolution of the progenitor's circumstellar medium, which is shaped by a slow red supergiant wind that is followed by a fast Wolf-Rayet (WR) wind. The main parameters of the simulations are the duration of the WR phase and the jet energy. We find that the jet is destroyed if the WR phase is sufficiently long and a massive circumstellar shell has formed. We therefore conclude that the WR phase must have been short (a few thousand yr), if present at all. Since the actual jet length of Cas A is not known we derive a lower limit for the jet energy, which is ~10^{48} erg. We discuss the implications for the progenitor of Cas A and the nature of its explosion.