An Analytical Density Profile of Dense Circumstellar Medium in Type II Supernovae

TL;DR

This paper presents an analytical model for the density profile of dense circumstellar media around Type II supernovae progenitors, based on a double power-law profile fitting simulation data, simplifying the characterization with two key parameters.

Contribution

It introduces a simple, two-parameter analytical density profile for CSM in Type II supernovae, derived from radiation hydrodynamical simulations, aiding future transient emission modeling.

Findings

Double power-law profile fits simulation data well.

CSM described by transition radius and density or total mass.

Profile simplifies modeling of supernova interaction emissions.

Abstract

Observations of Type II supernovae imply that a large fraction of its progenitors experience enhanced mass loss years to decades before core collapse, creating a dense circumstellar medium (CSM). Assuming that the CSM is produced by a single mass eruption event, we analytically model the density profile of the resulting CSM. We find that a double power-law profile, where the inner (outer) power-law index has a characteristic value of -1.5 (-10 to -12), gives a good fit to the CSM profile obtained using radiation hydrodynamical simulations. With our profile the CSM is well described by just two parameters, the transition radius $r_*$ and density at $r=r_*$ (alternatively $r_*$ and the total CSM mass). We encourage future studies to include this profile, if possible, when modelling emission from interaction-powered transients.