Non-relativistic radiation mediated shock breakouts: I. Exact bolometric planar breakout solutions

TL;DR

This paper presents exact numerical solutions and approximate analytic models for non-relativistic radiation mediated shock breakouts from stellar surfaces, improving understanding of supernova shock breakout luminosity and temperature.

Contribution

It provides the first exact numerical solutions for planar RMS breakouts with a power-law density profile and develops calibrated analytic expressions for luminosity and temperature.

Findings

Luminosity depends weakly on density profile index n.

Analytic solutions agree with numerical results when shock is far from surface.

Maximum surface temperature is lower than previous steady-state estimates.

Abstract

The problem of a non-steady planar radiation mediated shock (RMS) breaking out from a surface with a power-law density profile, \rho\propto x^n, is numerically solved in the approximation of diffusion with constant opacity. For an appropriate choice of time, length and energy scales, determined by the breakout opacity, velocity and density, the solution is universal, i.e. depends only on the density power law index n. The resulting luminosity depends weakly on the value of n. An approximate analytic solution, based on the self-similar hydrodynamic solutions and on the steady RMS solutions, is constructed and shown to agree with the numerical solutions as long as the shock is far from the surface, \tau>> c/v_{sh}. Approximate analytic expressions, calibrated based on the exact solutions, are provided, that describe the escaping luminosity as a function of time. These results can be used to calculate the bolometric properties of the bursts of radiation produced during supernova (SN) shock breakouts. For completeness, we also use the exact breakout solutions to provide an analytic approximation for the maximum surface temperature for fast (v_{sh}>~0.1) non-thermal breakouts, and show that it is few times smaller than inferred based on steady-state RMS solutions.