Forbidden Iron Lines and Dust Destruction in Supernova Remnant Shocks: The Case of N49 in the Large Magellanic Cloud

TL;DR

This study combines integral field spectroscopy and advanced shock modeling to analyze iron emission lines in supernova remnant N49, revealing significant dust destruction through sputtering and collisions in fast shocks.

Contribution

It provides the first detailed abundance and dynamical analysis of optical Fe lines in a supernova remnant using the new MAPPINGS 5.1 code, linking dust destruction to ionization stages.

Findings

30% - 90% destruction of Fe-bearing dust in fast shocks

Confirmation of non-thermal sputtering and grain collisions as main destruction mechanisms

Detailed ionization-dependent dust depletion factors derived

Abstract

We present results of a complete integral field survey of the bright SNR N49 in the LMC, obtained with the WiFeS instrument mounted on the ANU 2.3m telescope at Siding Spring Observatory. From theoretical shock modelling with the new MAPPINGS 5.1 code we have, for the first time, subjected the optical Fe emission line spectrum of a supernova remnant to a detailed abundance and dynamical analysis covering 8 separate stages of ionisation. This allows us to derive the dust depletion factors as a function of ionisation stage. We have shown that there is substantial (30% - 90%) destruction of Fe-bearing dust grains in these fast shocks ($v_s \sim 250$ km/s), and we have confirmed that the dominant dust destruction is through the non-thermal sputtering and grain-grain collision mechanisms developed in a number of theoretical works.