Infrared Ejecta and Cold Dust in the Young Supernova Remnant N132D

Abstract

We present Spitzer, WISE, and Herschel observations of the young supernova remnant (SNR) N132D in the LMC, including 3-40 microns Spitzer IRS mapping, 12 microns WISE and 70, 100, 160, 250, 350, and 500 microns Herschel images. The high-velocity lines of [Ne II] at 12.8 microns, [Ne III] at 15.5 microns, and [O IV] 26 microns reveal infrared ejecta concentrated in a central ring and coincide the optical and X-ray ejecta. Herschel images reveal far-IR emission coinciding with the central ejecta, which suggests that the IR emission is freshly formed, cold dust in the SN-ejecta. The infrared spectra are remarkably similar to those of another young SNR of 1E0102 with Ne and O lines. Shock modeling of the Ne ejecta emission suggests a gas temperature of 300 - 600 K and densities in the range 1000-20,000 cm^{-3} in the post-shock photoionized region. The IR continuum from the ejecta shows an 18 microns-peak dust feature. We performed spectral fitting to the IRS dust continuum and Herschel photometry. The dust mass associated with the central ejecta is 1.25+-0.65 Msun, while the 18 microns dust feature requires forsterite grains. The dust mass of the central ejecta region in N132D is higher than those of other young SNRs, which is likely associated with its higher progenitor mass. We discuss the dust productivity in the ejecta of N132D and infer its plausible implications for the dust in the early Universe.