Suzaku Observations of the Supernova Remnant N23 in the Large Magellanic Cloud

TL;DR

This study uses Suzaku X-ray data to analyze the supernova remnant N23 in the LMC, revealing new thermal components, refining ionization timescales, and estimating its age and elemental abundances.

Contribution

First detection of a low-temperature thermal emission component in N23, leading to revised ionization timescale and age estimates, and confirming the origin of X-ray emission as swept-up ambient material.

Findings

Identified a new ~0.2 keV thermal component.

Revised ionization timescale to >10^{12} cm^{-3}s.

Estimated N23's age to be ~8000 years.

Abstract

X-ray emission from the supernova remnant N23 in the Large Magellanic Cloud (LMC) is studied using the X-ray Imaging Spectrometer (XIS) onboard Suzaku. Thanks to superior energy resolution of the XIS in the soft X-ray band, we resolved H-like and He-like Oxygen K\alpha emission lines from N23 with unprecedentedly high quality, and as a result, identified a new optically thin thermal emission component with a temperature ~0.2 keV, as well as that with a temperature of ~0.5-0.7 keV previously known. This alters the estimate of the ionization timescale net from ~10^{10-11} cm^-3s to >~10^{12} cm^{-3}s. Under the assumption that N23 is still in the Sedov phase, its age evaluated from the newly discovered low temperature component is ~8000 yr, although it is possible that N23 has already moved into the radiative phase. The abundances of the heavy elements are found to be roughly consistent with those of the LMC average, which indicates that the origin of the X-ray emission of N23 is swept-up ambient material, as expected from its ionization timescale.