Multiwavelength Study of the X-ray Bright Supernova Remnant N522-S48 in NGC 522

We present a multiwavelength examination of the supernova remnant (SNR) S26 in the nearby galaxy NGC 300 using data from Chandra X-ray Observatory, XMM-Newton X-ray Observatory, Hubble Space Telescope (HST), the Very Large Array, and the Australia Telescope Compact Array. We simultaneously fit all of the available X-ray data with a thermal plasma model and find a temperature of 0.77±0.13 keV with a hydrogen column density of (9.7+6.4 −4.8)×1020 cm−2. HST imaging allows us to measure a semimajor axis of 0.78±0.10 arcsec (7.5±1.0 pc) and a semiminor axis of 0.69+0.14 −0.12 arcsec (6.7+1.2 −1.4 pc). This precise size helps to constrain the age and velocity of the shock to be (3.3+0.7 −0.6)×103 yr and 411+275 −122 km s−1. We also fit photometry of the surrounding stars to infer the age and mass of the progenitor star to be 8±1 Myr and 25+1 −5 M. Based on measured radio properties of the source and assuming equipartition, the estimated radio luminosity of 1.7×1034 erg s−1 over the 108 to 1011 Hz frequency range results in a minimum magnetic field associated with this SNR of 0.067 mG and the minimum energy needed to power the observed synchrotron emission of 1.5× 1049 erg. The size and temperature of N300-S26 appear to be similar to the Galactic SNR G311.5–0.3 except that G311.5–0.3 has a significantly lower X-ray luminosity, is older, and has a slower shock velocity