Supernovae (SNe) are of great interest for a number of reasons, one of which being their interactions with the surrounding medium. The propulsion of a high-energy shock through the circumstellar medium (CSM) creates a complex density structure, with turbulence and instabilities shaping the shocked material. The radiation emitted and absorbed in these circumstances is heavily affected by the nature of the CSM. While SNe might be surrounded by a simple wind, dense shells and rings can also be formed from more complex wind interactions and periods of stellar mass loss. This project, as a continuation of project SNIC 2018/3-273, simulates supernova shocks and their interactions with various circumstellar media through the use of a hydrodynamical code. Then, through post-processing, we calculate the X-ray and radio emission produced by the shock system, taking absorption of the rest of the ejecta into account. By running these simulations in 2D we can investigate the effects of turbulence and multi-dimensional instabilities on the structure of the shock as well as the emitted spectrum. 2D simulations also allows us to simulate asymmetrical CSM structures.
This will allow for interesting comparisons to previous studies which were only run in one dimension, such as Chugai & Chevalier (2006). The spectra obtained from the results of the hydro code let us compare our results to observations of supernovae that display strong CSM interactions, such as 2001em and 2014C. These observations are discussed in Chugai & Chevalier (2006) and Margutti et al. (2017), respectively, as well as other sources. During the previous project, of which this is a continuation, we added complexity to the CSM in the form of multiple species. This allows us to simulate cooling more realistically by having separate cooling functions for the ejecta, composed of Oxygen or Helium, and the CSM, made of Hydrogen. We are currently investigating the possible influence of Inverse Compton emission/absorption on the radio spectrum of SN 2014C. This involves testing new CSM structures consisting of an equatorial disk in a smooth wind CSM. The low usage at the start of the previous allocation can be explained by a reliance on 1D simulations to test new additions to the simulations, as well as a lack of work due to vacation. We would like to apply for the same 100k core-hours per month that we had in the previous project.
The hydrodynamical simulations are done using FLASH, an established hydrodynamical code. The modular nature of the code has made it easy to implement a cooling function, allowing us to account for the impact of optically thin cooling on shock dynamics. Implementing the cooling shortens the time-step significantly, however, which increases the computing cost of the code. The use of powerful computing infrastructure allows us to investigate more complete cooling functions, as well as making larger-scale, higher resolution, simulations feasible.