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Arxiv: A First-look at Spatially-resolved Infrared Supernova Remnants in M33 with JWST Published: 10/15/2024 8:49:07 PM Updated: 10/15/2024 8:49:07 PM

Paper abstract: We present the first spatially-resolved infrared images of supernova remnants(SNRs) in M33 with the unprecedented sensitivity and resolution of JWST. Weanalyze 43 SNRs in four JWST fields: two covering central and southern M33 withseparate NIRCam (F335M, F444W) and MIRI (F560W, F2100W) observations, one~5 kpc-long radial strip observed with MIRI F770W, and one covering thegiant HII region NGC 604 with multiple NIRCam and MIRI broad/narrowbandfilters. Of the 21 SNRs in the MIRI field, we found three clear detections(i.e., identical infrared and \ha morphologies), and six partial-detections,implying a detection fraction of 43\% in these bands. In contrast, only one SNR(out of 16) is detectable in the NIRCam field. One of the SNRs, L10-080, is apotential candidate for having freshly-formed ejecta dust, based on its sizeand centrally-concentrated 21 \mum emission. Two SNRs near NGC 604 have strongevidence of molecular (H_2) emission at 4.7 \mum, making them the farthestknown SNRs with visible molecular shocks. Five SNRs have F770W observations,with the smaller younger objects showing tentative signs of emission, while theolder, larger ones have voids. Multi-wavelength data indicate that theclearly-detected SNRs are also among the smallest, brightest at otherwavelengths (\ha, radio and X-ray), have the broadest line widths (H\alphaFWHM~250-350 km/s), and the densest environments. No strong correlationwith star-formation histories are seen, with the clearly-detected SNRs havingboth high-mass (~35 \Msun) and low-mass (<~10 \Msun) progenitors.