Using Spitzer to Search For Dust Signatures in Evolved Supernova Remnants

Using the Spitzer Space Telescope, we have undertaken a spectral mapping program for three Large Magellanic Cloud supernova remnants (SNRs), LHa 120-N49, N63, and N11L, which show signs of significant interactions with the surrounding ISM. Previous imaging and uncalibrated spectral observations of these objects did not turn up strong evidence for the presence of thermal continuum emission, as would be expected from hot dust. We therefore have undertaken to investigate whether this result can be confirmed with fully calibrated spectra; and, if so, whether the entire remnant lacks such emission, or whether there are significant spatial variations. We here present our preliminary results from this spectral mapping project. We have confirmed the findings from previous work, in that certain selected regions show little if any continuum emission. We also find, however, that other regions within the SNRs show varying levels of continuum emission. The full maps of these SNRs may cast new light on areas of dust concentration and, possibly, destruction within SNRs. This work is based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. Support for this work was provided by NASA through an award issued by JPL/Caltech. Additional support for the authors was provided through NASA Long-Term Space Astrophysics grant NNG05GC97G.