Supernova Remnants and the Interstellar Medium of M83: Imaging & Photometry with WFC3 on HST

Abstract

We present Wide Field Camera 3 images taken with the Hubble Space Telescope within a single field in the southern grand design star-forming galaxy M83. Based on their size, morphology and photometry in continuum-subtracted H\(\alpha\), [\SII], H\(\beta\), [\OIII] and [\OII] filters, we have identified 60 supernova remnant candidates, as well as a handful of young ejecta-dominated candidates. A catalog of these remnants, their sizes and, where possible their H\(\alpha\) fluxes are given. Radiative ages and pre-shock densities are derived from those SNR which have good photometry. The ages lie in the range \(2.62 < log(\tau_{\rm rad}/{\rm yr}) < 5.0\), and the pre-shock densities at the blast wave range over \(0.56 < n_0/{\rm cm^{-3}} < 1680\). Two populations of SNR have been discovered. These divide into a nuclear and spiral arm group and an inter-arm population. We infer an arm to inter-arm density contrast of 4. The surface flux in diffuse X-rays is correlated with the inferred pre-shock density, indicating that the warm interstellar medium is pressurised by the hot X-ray plasma. We also find that the interstellar medium in the nuclear region of M83 is characterized by a very high porosity and pressure and infer a SNR rate of one per 70-150 yr for the nuclear (\(R<300 \)pc) region. On the basis of the number of SNR detected and their radiative ages, we infer that the lower mass of Type II SNe in M83 is \(M_{\rm min} = 16^{+7}_ {-5}\) M\(_{\odot}\). Finally we give evidence for the likely detection of the remnant of the historical supernova, SN1968L.