An X-ray, Optical and Radio Search for Supernova Remnants in the Nearby Sculptor Group Sd Galaxy NGC 7793

This paper is the second in a series devoted to examining the multi-wavelength properties of supernova remnants (SNRs) located in nearby galaxies. We consider here the resident SNRs in the nearby Sculptor Group Sd galaxy NGC 7793. Using our own Very Large Array (VLA) radio observations at 6 and 20 cm, as well as archived ROSAT X-ray data, previously published optical results and our own Hα image, we have searched for X-ray and radio counterparts to previously-known optically-identied SNRs, and for new previously unidentied SNRs at these two wavelength regimes. Consistent with our prior results for NGC 300, only a tiny minority of the optically-identied SNRs have been found at another wavelength. The most noteworthy source in our study is N7793-S26, which is the only SNR in this galaxy that is detected at all three wavelengths (X-ray, optical and radio). It features a long ( 450 parsecs) lamentary morphology that is clearly seen in both the optical and the radio images. N7793-S26’s radio luminosity exceeds that of the Galactic SNR Cas A, and based on equipartition calculations we determine that an energy of at least 1052 ergs is required to maintain this source. Suc