Numerical Simulations of Supernova Remnant Evolution in a Cloudy Interstellar Medium

TL;DR

This paper uses numerical hydrodynamical simulations to study supernova remnant evolution in a cloudy interstellar medium, testing and extending the White & Long analytical model with detailed emission predictions.

Contribution

It provides the first detailed 2D and 3D numerical models including thermal conduction, revealing differences from the White & Long model and emphasizing the role of cloud evaporation and conduction effects.

Findings

X-ray luminosity peaks early due to shocked cloud gas

Thermal conduction causes further flattening of X-ray brightness

Simulations show lower X-ray temperatures and altered emission profiles

Abstract

The mixed morphology class of supernova remnants has centrally peaked X-ray emission along with a shell-like morphology in radio emission. White & Long proposed that these remnants are evolving in a cloudy medium wherein the clouds are evaporated via thermal conduction once being overrun by the expanding shock. Their analytical model made detailed predictions regarding temperature, density and emission profiles as well as shock evolution. We present numerical hydrodynamical models in 2D and 3D including thermal conduction, testing the White & Long model and presenting results for the evolution and emission from remnants evolving in a cloudy medium. We find that, while certain general results of the White & Long model hold, such as the way the remnants expand and the flattening of the X-ray surface brightness distribution, in detail there are substantial differences. In particular we find that the X-ray luminosity is dominated by emission from shocked cloud gas early on, leading to a bright peak which then declines and flattens as evaporation becomes more important. In addition, the effects of thermal conduction on the intercloud gas, which is not included in the White & Long model, are important and lead to further flattening of the X-ray brightness profile as well as lower X-ray emission temperatures.