XRISM Observes Supernova Remnant N132D: Key Findings on Velocity and Thermal Properties

The XRISM (X-ray Imaging and Spectroscopy Mission) has conducted its first light observation of the supernova remnant N132D, located in the Large Magellanic Cloud. This observation marks a significant advancement in high-resolution X-ray spectroscopy, utilizing the Resolve microcalorimeter to capture a spectrum in the 1.6-10 keV range. The findings reveal K-shell emission lines from elements such as silicon (Si), sulfur (S), argon (Ar), calcium (Ca), and iron (Fe).

The analysis indicates that the Si and S lines exhibit a relatively narrow profile, characterized by a Gaussian-like velocity dispersion of approximately 450 km/s. In contrast, the Fe Heα lines show substantial broadening, with a velocity dispersion of around 1670 km/s. This broadening is attributed to both thermal Doppler effects, stemming from high ion temperatures, and kinematic Doppler effects due to the expansion of the supernova remnant.

Furthermore, the study estimates the reverse shock velocity during the period when the bulk of the iron ejecta were shock-heated to be between -1000 km/s and 3300 km/s, as observed. The Fe Lyα emission is also noted to be redshifted, with a bulk velocity of approximately 890 km/s, which is significantly greater than the radial velocity of the local interstellar medium surrounding N132D.

These results underscore the capability of high-resolution X-ray spectroscopy to provide insights into the evolutionary stages, geometrical configurations, and velocity distributions of supernova remnants. The research was conducted by the XRISM Collaboration and is documented in the paper titled "The XRISM First Light Observation: Velocity Structure and Thermal Properties of the Supernova Remnant N132D" (arXiv:2408.14301).