ASpitzer Space TelescopeInfrared Survey of Supernova Remnants in the Inner Galaxy

Using Infrared Array Camera (IRAC) images at 3.6, 4.5, 5.8, and 8 micronsfrom the GLIMPSE Legacy science program on the Spitzer Space Telescope, wesearched for infrared counterparts to the 95 known supernova remnants that arelocated within galactic longitudes 65>|l|>10 degrees and latitudes |b|<1degree. Eighteen infrared counterparts were detected. Many other supernovaremnants could have significant infrared emission but are in portions of theMilky Way too confused to allow separation from bright HII regions andpervasive mid-infrared emission from atomic and molecular clouds along the lineof sight. Infrared emission from supernova remnants originates from synchrotronemission, shock-heated dust, atomic fine-structure lines, and molecular lines.The detected remnants are G11.2-0.3, Kes 69, G22.7-0.2, 3C 391, W 44, 3C 396,3C 397, W 49B, G54.4-0.3, Kes 17, Kes 20A, RCW 103, G344.7-0.1, G346.6-0.2, CTB37A, G348.5-0.0, and G349.7+0.2. The infrared colors suggest emission frommolecular lines (9 remnants), fine-structure lines (3), and PAH (4), or acombination; some remnants feature multiple colors in different regions. Noneof the remnants are dominated by synchrotron radiation at mid-infraredwavelengths. The IRAC-detected sample emphasizes remnants interacting withrelatively dense gas, for which most of the shock cooling occurs throughmolecular or ionic lines in the mid-infrared.Comment: Accepted 10/18/2005 for publication in "The Astronomical Journal". The figures in this astro-ph submission are drastically reduced in quality in order to fit within its limit