Physical Properties of the Supernova Remnant Population in the Small Magellanic Cloud

Abstract

The X-ray emission from a supernova remnant is a powerful diagnostic of the state of its shocked plasma. The temperature and the emission measure are related to the energy of the explosion, the age of the remnant, and the density of the surrounding medium. Here we present the results of a study of the remnant population of the Small Magellanic Cloud. Progress in X-ray observations of remnants has resulted in a sample of 20 remnants in the Small Magellanic Clound with measured temperatures and emission measures. We apply spherically symmetric supernova remnant evolution models to this set of remnants, to estimate ages, explosion energies, and circumstellar medium densities. The distribution of ages yields a remnant birthrate of $\sim$1/1200 yr. The energies and densities are well fit with log-normal distributions, with means of 1.6$\times10^{51}$ erg and 0.14 cm$^{-3}$, and 1$\sigma$ dispersions of a factor of 1.87 in energy and 3.06 in density, respectively.Comment: 23 pages, 5 figures, accepted for publication in The Astrophysical Journa