Spitzer and Herschel studies of dust in supernova remnants in the Small
  Magellanic Cloud
  With the entire Small Magellanic Cloud (SMC) mapped by the Spitzer Space
Telescope and Herschel Space Observatory, we were able to search 8-250 micron
images in order to identify infrared (IR) emission associated with SMC
supernova remnants (SNRs). A valid detection had to correspond with known
X-ray, Halpha and radio emission from the SNRs. From the 24 known SNRs, we made
5 positive detections with another 5 possible detections. Two detections are
associated with pulsars or pulsar wind nebula, and another three detections are
part of the extended nebulous emission from the SNRs. We modelled dust emission
where fast moving electrons are predicted to collide and heat dust grains which
then radiate in IR. With known distance (62.44+-0.47kpc), measured SNR sizes,
electron densities, temperatures from X-ray emission as well as hydrogen
densities, the modelling of SMC SNRs is straightforward.
  If the higher range of hydrogen and electron densities were to be accepted,
we would expect almost all SMC SNRs to be detected in the IR, at least at 24
micron, but the actual detection rate is only 25%. One possible and common
explanation for this discrepancy is that small grains have been destroyed by
the SNRs shockwave. However, within the uncertainties of hydrogen and electron
densities, we find that infrared dust emission can be explained reasonably
well, without invoking dust destruction. There is no conclusive evidence that
SNRs destroy swept-up ISM dust.
