Average Opacity Calculation for Core-collapse Supernovae

Supernovae (SNe) are among the most intensely studied objects of modern astrophysics, but due to their complex physical nature, theoretical models are essential to better understand these exploding stars, as well as the properties of the variation of the emitted radiation. One possibility for modeling SNe light curves (LCs) is the construction of a simplified semianalytic model, which can be used for getting order-of magnitude estimates of the SN properties. One of the strongest simplifications in most of these LC models is the assumption of the constant Thomson-scattering opacity that can be determined as the average opacity of the ejecta. Here we present a systematic analysis for estimating the average opacity in different types of core-collapse supernovae that can be used as the constant opacity of the ejecta in simplified semianalytic models. To use these average opacities self-consistently during LC fit, we estimate their values from hydrodynamic simulations. In this analysis, we first generate MESA stellar models with different physical parameters (initial mass, metallicity, and rotation), which determine the mass-loss history of the model star. Then we synthesize SN LCs from these models with the SNEC hydrodynamic code and calculate the Rosseland mean opacity in every mass element. Finally, we compute the average opacities by integrating these Rosseland mean opacities. As a result, we find that the average opacities from our calculations show adequate agreement with the opacities generally used in previous studies.