2006ApJ...652L..33W

We report observations with the Multiband Imaging Photometer for Spitzer of four supernova remnants (SNRs) believed to be the result of core-collapse supernovae: N132D (0525-69.6), N49B (0525-66.0), N23 (0506-68.0), and 0453-68.5. All four of these SNRs were detected in whole at 24 µm and in part at 70 µm. Comparisons with Chandra broadband X-ray images show an association of infrared (IR) emission with the blast wave. We attribute the observed IR emission to dust that has been collisionally heated by electrons and ions in the hot, X-ray-emitting plasma, with grain size distributions appropriate for the LMC and the destruction of small grains via sputtering by ions. As with our earlier analysis of Type Ia SNRs, models can reproduce observed 70 µm/24 µm flux ratios only if effects from sputtering are included, destroying small grains. We calculate the mass of dust swept up by the blast wave in these remnants, and we derive a dust-to-gas mass ratio of several times less than the often assumed value of 0.25% for the LMC. We believe that one explanation for this discrepancy could be porous (fluffy) dust grains.