A spectral synthesis code for rapid modelling of supernovae

• Published in: Monthly notices of the Royal Astronomical Society Vol. 440; no. 1; pp. 387 - 404
• Main Authors: Kerzendorf, Wolfgang E., Sim, Stuart A.
• Format: Journal Article
• Language: English
• Published: London Oxford University Press 01.05.2014
• Subjects: Approximation; Astrophysics; Comparative analysis; Monte Carlo simulation; Plasma physics; Spectrum analysis; Supernovae; methods: numerical; supernovae: general; radiative transfer
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1093/mnras/stu055

We present tardis - an open-source code for rapid spectral modelling of supernovae (SNe). Our goal is to develop a tool that is sufficiently fast to allow exploration of the complex parameter spaces of models for SN ejecta. This can be used to analyse the growing number of high-quality SN spectra being obtained by transient surveys. The code uses Monte Carlo methods to obtain a self-consistent description of the plasma state and to compute a synthetic spectrum. It has a modular design to facilitate the implementation of a range of physical approximations that can be compared to assess both accuracy and computational expediency. This will allow users to choose a level of sophistication appropriate for their application. Here, we describe the operation of the code and make comparisons with alternative radiative transfer codes of differing levels of complexity (syn++, python and artis). We then explore the consequence of adopting simple prescriptions for the calculation of atomic excitation, focusing on four species of relevance to Type Ia SN spectra - Si ii, S ii, Mg ii and Ca ii. We also investigate the influence of three methods for treating line interactions on our synthetic spectra and the need for accurate radiative rate estimates in our scheme.