Supernova Remnants in the AKARI IRC Survey of the Large Magellanic Cloud

Abstract

Abstract We present a near- to mid-infared study of supernova remnants (SNRs) using the AKARI IRC Survey of the Large Magellanic Cloud (LMC). The LMC survey observed about a 10 square degree area of the LMC in five bands centered at 3, 7, 11, 15, and 24$\mu$m using the Infrared Camera (IRC) aboard AKARI. The number of SNRs in the survey area is 21, which is about a half of the known LMC SNRs. We systematically examined AKARI images and identified eight SNRs with distinguishable infrared emission. All of them were detected at $\gtrsim$10$\mu$m and some at 3 and 7$\mu$m, too. We present their AKARI images and fluxes. In the 11$/$15$\mu$m versus 15$/$24$\mu$m color-color diagram, the SNRs appear to be aligned along a modified blackbody curve, representing thermal emission from dust at temperatures of between 90 and 190K. There is a good correlation between the 24$\mu$m and X-ray fluxes of the SNRs. It was also found that there is a good correlation between the 24$\mu$m and radio fluxes even if there is no direct physical connection between them. We considered the origin of the detected mid-infrared emission in individual SNRs. We conclude that the mid-infrared emissions in five SNRs that show morphologies similar to the X-rays are dominated by thermal emission from hot dust heated by X-ray emitting plasma. Their 15$/$24$\mu$m color temperatures are generally higher than the Spitzer 24$/$70$\mu$m color temperatures, which suggests that a single-temperature dust model cannot describe the full spectral energy distribution (SED) of the SNRs. It also implies that our understanding of the full SED is essential for estimating the dust destruction rate of grains by SNR shocks.