A Near-Infrared [P II] and [Fe II] Line Survey of Supernova Remnants in the Magellanic Clouds

Supernova (SN) explosions play a major role in the physical and chemical evolution of the interstellar medium (ISM). They supply newly synthesized heavy elements and distribute them throughout the ISM. And additionally, they also supply and destroy dust grains that introduce heavy elements into the ISM.

We observed 17 young and middle-aged supernova remnants (SNRs) in the Large and Small Magellanic Clouds (LMC and SMC, respectively) to investigate dust destruction by SNR shocks, and possible detection of SN ejecta material. Given their proximity, near-frontal geometries, and low galactic foreground absorption, the LMC and SMC are ideal for studying SNRs in great detail. We have analyzed [P II] (1.189 μm) and [Fe II] (1.257 μm and 1.644 μm) narrowband images obtained with the InfraRed Survey Facility (IRSF) 1.4 m telescope at the South African Astronomical Observatory (SAAO). The [P II] narrowband filter has been recently developed and manufactured as part of this research and represents the first time that [P II] emission has been used in imaging observations.

Among the 17 SNRs, we detected 6 SNRs showing both [P II] and [Fe II] emissions. We estimated the P/Fe abundance ratio using the [P II]/[Fe II] line ratio, which provides a good indication of dust content in the ISM since P is not depleted while Fe is a refractory species. In some SNRs, the P/Fe abundance ratios are lower than the general ISM (e.g., Orion Bar), suggesting that there is significant destruction of dust grains by shocks. While in some SNRs, the P/Fe abundance ratios are found to be comparable to or higher than the general ISM. We carried out follow-up spectroscopic studies using GMOS-S on the 8.2 m Gemini-South telescope, and the results will be presented.