The First Reported Infrared Emission from the SN 1006 Remnant

TL;DR

This study presents the first infrared observations of the SN 1006 remnant, revealing dust heated by the shock, with findings indicating rapid dust destruction and a lower dust-to-gas ratio than typical interstellar values.

Contribution

First infrared imaging and spectroscopy of SN 1006, providing new insights into dust heating, destruction, and the dust-to-gas ratio in supernova remnants.

Findings

Infrared emission traces shock-heated dust near the NW rim.

Rapid decline in IR emission suggests higher dust destruction rates.

Lower dust-to-gas ratio than expected for Galactic ISM.

Abstract

We report results of infrared imaging and spectroscopic observations of the SN 1006 remnant, carried out with the Spitzer Space Telescope. The 24 micron image from MIPS clearly shows faint filamentary emission along the northwest rim of the remnant shell, nearly coincident with the Balmer filaments that delineate the present position of the expanding shock. The 24 micron emission traces the Balmer filaments almost perfectly, but lies a few arcsec within, indicating an origin in interstellar dust heated by the shock. Subsequent decline in the IR behind the shock is presumably due largely to grain destruction through sputtering. The emission drops far more rapidly than current models predict, however, even for a higher proportion of small grains than would be found closer to the Galactic plane. The rapid drop may result in part from a grain density that has always been lower -- a relic effect from an earlier epoch when the shock was encountering a lower density -- but higher grain destruction rates still seem to be required. Spectra from three positions along the NW filament from the IRS instrument all show only a featureless continuum, consistent with thermal emission from warm dust. The dust-to-gas mass ratio in the pre-shock interstellar medium is lower than that expected for the Galactic ISM -- as has also been observed in the analysis of IR emission from other SNRs but whose cause remains unclear. As with other SN Ia remnants, SN 1006 shows no evidence for dust grain formation in the supernova ejecta.