Destruction of Interstellar Dust in Evolving Supernova Remnant Shock Waves

TL;DR

This study models the destruction of interstellar dust by supernova remnant shocks, showing that evolving, radiative shocks increase dust survival timescales compared to previous steady shock models, impacting our understanding of dust lifecycle.

Contribution

It introduces new calculations of dust destruction in evolving supernova remnants, accounting for radiative effects and different ISM conditions, improving upon steady shock assumptions.

Findings

Dust destruction timescales are ~2-3 Gyr in a warm ISM.

Evolving shocks increase destruction timescales compared to steady shocks.

Results help reconcile dust lifecycle timescales with supernova rates.

Abstract

Supernova generated shock waves are responsible for most of the destruction of dust grains in the interstellar medium (ISM). Calculations of the dust destruction timescale have so far been carried out using plane parallel steady shocks, however that approximation breaks down when the destruction timescale becomes longer than that for the evolution of the supernova remnant (SNR) shock. In this paper we present new calculations of grain destruction in evolving, radiative SNRs. To facilitate comparison with the previous study by Jones et al. (1996), we adopt the same dust properties as in that paper. We find that the efficiencies of grain destruction are most divergent from those for a steady shock when the thermal history of a shocked gas parcel in the SNR differs significantly from that behind a steady shock. This occurs in shocks with velocities >~ 200 km/s for which the remnant is just beginning to go radiative. Assuming SNRs evolve in a warm phase dominated ISM, we find dust destruction timescales are increased by a factor of ~2 compared to those of Jones et al. (1996), who assumed a hot gas dominated ISM. Recent estimates of supernova rates and ISM mass lead to another factor of ~3 increase in the destruction timescales, resulting in a silicate grain destruction timescale of ~2-3 Gyr. These increases, while not able resolve the problem of the discrepant timescales for silicate grain destruction and creation, are an important step towards understanding the origin, and evolution of dust in the ISM.