From total destruction to complete survival: Dust processing at different evolutionary stages in the supernova remnant Cassiopeia A

TL;DR

This study models dust destruction in supernova remnant Cassiopeia A, revealing how dust survival varies with remnant age and grain size, and showing most dust is destroyed early on but larger grains survive better over time.

Contribution

It provides a detailed simulation-based analysis of dust survival rates at different evolutionary stages of Cassiopeia A, highlighting the impact of reverse shocks on dust destruction.

Findings

Most dust is hit by the reverse shock within 350 years after explosion.

Dust destruction is nearly complete within the first 200 years.

Larger grains have higher survival fractions over the remnant's evolution.

Abstract

The expanding ejecta of supernova remnants (SNRs) are believed to form dust in dense clumps of gas. Before the dust can be expelled into the interstellar medium and contribute to the interstellar dust budget, it has to survive the reverse shock that is generated through the interaction of the preceding supernova blast wave with the surrounding medium. The conditions under which the reverse shock hits the clumps change with remnant age and define the dust survival rate. To study the dust destruction in the SNR Cassiopeia A, we conduct magnetohydrodynamical simulations of the evolution of a supernova blast wave and of the reverse shock. In a second step we use these evolving conditions to model clumps that are disrupted by the reverse shock at different remnant ages. Finally, we compute the amount of dust that is destroyed by the impact of the reverse shock. We find that most of the dust in the SNR is hit by the reverse shock within the first 350 yr after the SN explosion. While the dust destruction in the first 200 yr is almost complete, we expect greater dust survival rates at later times and almost total survival for clumps that are first impacted at ages beyond 1000 yr. Integrated over the entire evolution of the SNR, the dust mass shows the lowest survival fraction (17 per cent) for the smallest grains (1 nm) and the highest survival fraction (28 per cent) for the largest grains (1000 nm).