ACP Seminar (Astronomy - Cosmology - Particle Physics)

Speaker: Elena Sorokina (Sternberg)
Title: Expansion opacity for type Ia supernovae: How to survive when you need to use more than 10 million spectral lines
Date (JST): Thu, Feb 28, 2013, 14:00 - 15:00
Place: Seminar Room A
Related File: 893.pdf
Abstract: Modern study of supernova light curves relies on detailed radiative transfer calculations. This requires accurate implementation of all sources of opacity. Spectral lines are the main source of opacity for type Ia supernovae (SN Ia). The correct and fast treatment of them is needed very much to produce light curves of SN Ia. We confirm the result of other authors that a line list of tens million lines is needed to calculate SN Ia light curve correctly. Taking them into account directly, line by line, for each mesh zone at each time step should take too much run time. We propose a new method of line opacity calculation in Sobolev approximation for freely expanding ejecta of supernovae. The method is partly based on the ideas of the method of opacity distribution function, but we save a distribution of lines for different physical conditions instead of values of opacity itself, which allows us to use the same tables for any chemical composition. The method highly reduces time needed for calculation of supernova light curves.
For huge line lists which contain tens illion lines, the code becomes more than 100 times faster with using these tables instead of direct opacity calculation.