UNIVERSITÄT ZU KÖLN

Katya Makarenko

Radiative cooling is one of the fundamental processes in astrophysical plasma that governs the energy balance and thermal evolution. Radiative cooling from supernovae (SN) plays a significant role in the energy and momentum input for the surrounding interstellar medium (ISM). Typically, radiative cooling is treated optically thin in ISM simulations because of the high computational costs. This makes high-resolution 3D simulations unphysical. The growing ability of X-ray imaging spectroscopy allows observations of SN remnants (SNRs) to define pixel-by-pixel based parameters (such as plasma temperature, ionisation state, and abundance of different elements). We therefore urgently need more realistic simulations of SNRs.

This work is one of the first implementations of radiative cooling emission from a SNR treated self-consistently on the fly in ISM hydrodynamic simulations using the FLASH code. Our new SPECTRE module allows us to calculate the cooling energy in different energy bands (user-defined) from extended sources like SNRs. We calculate the emission and absorption on the fly using backward ray tracing with the TreeRay module (Wünsch et al., 2021). Each cell within the SNR is treated as a source of radiation. It is also coupled to the Chemistry non-equilibrium network (Nelson & Langer 1999; Glover et al. 2011), so the most important heating and cooling processes are taken into account. To simulate the SNR we use the 3-D Sedov explosion problem (Sedov 1965). The simulation box has a volume of (400 pc)³ with isolated boundary conditions. Initial conditions of the simulations are the following: n = 10 cm^-3, T = 300 K with the maximum resolution of 0.5 pc. We let the SNR evolve during the first 70 years to simulate thermal X-ray emission. As a result, we created synthetic maps of the simulated SNR in several X-ray energy bands.

Understanding radiative cooling in SNRs is essential for accurately modeling their evolution, and interpreting the observed spectra and images.