Radio observations of the X-ray supernova remnant G272.2– 3.2

Abstract

Radio continuum observations are presented for the recently discovered X-ray supernova remnant (SNR) G272.2 - 3.2. Radio emission from this SNR has never before been detected. We find this remnant to have a non-thermal radio spectral index of 0.55 ± 0.15 (S ∝ λ), and an almost circular appearance with a diameter of approximately 15 arcmin (in agreement with the X-ray size). High-resolution observations with the Australia Telescope Compact Array (ATCA) reveal the remnant to consist of a series of faint filaments and patches of emission, with a maximum surface brightness of 10 mJy beam area at 1.4 GHz, and a diffuse emisson component. This diffuse emission appears to be produced by shock-accelerated electrons. Modest spectral index variations are seen across the SNR, indicating that G272.2 - 3.2 contains no significant thermal or plerionic component. Optical filaments in the region appear to align well with the radio 'blobs', whilst the X-ray enhancements show no correlation with the 'blobs'. These correlations are consistent with a somewhat higher age for the remnant than is derived from the X-ray data; perhaps 6 × 10 yr or so. Within the sensitivity of the observations no polarized emission was detected from G272.2 - 3.2, which is possibly indicative of a highly twisted magnetic field.