Monte Carlo techniques for time-dependent radiative transfer in 3-D supernovae

Astrophysics Group, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ, UK e-mail: l.lucy@imperial.ac.uk

Received: 13 July 2004
Accepted: 7 September 2004

Abstract

Monte Carlo techniques based on indivisible energy packets are described for computing light curves and spectra for 3-D supernovae. The radiative transfer is time-dependent and includes all effects of . Monte Carlo quantization is achieved by discretizing the initial distribution of  into  radioactive pellets. Each pellet decays with the emission of a single energy packet comprising γ-ray photons representing one line from either the  or the  decay spectrum. Subsequently, these energy packets propagate through the homologously-expanding ejecta with appropriate changes in the nature of their contained energy as they undergo Compton scatterings and pure absorptions.
The 3-D code is tested by applying it to a spherically-symmetric SN in which the transfer of optical radiation is treated with a grey absorption coefficient. This 1-D problem is separately solved using Castor's co-moving frame moment equations. Satisfactory agreement is obtained.
The Monte Carlo code is a platform onto which more advanced treatments of the interactions of matter and radiation can be added. Some of these have already been developed and tested in previous papers and are summarized here.