The application of Monte Carlo methods to the synthesis of earlytime supernovae spectra.
Abstract
The application of a Monte Carlo technique for treating multiline transfer in a supernova's expanding envelope and thereby computing synthetic earlytime spectra is described. The main physical assumptions are discussed, especially where they differ from the previous application to stellar winds. These include the calculation of the density and temperature stratification in the envelope, a more realistic treatment of ionization, and the treatment of radiative transfer on the assumption of a purely scattering atmosphere (SchusterSchwarzschild model). A detailed outline of the code, which has already been applied successfully to both supernovae (SNe) II and Ia, is also given, and the main advantages of using Monte Carlo methods for the synthesis of supernova (SN) spectra are emphasized. These lie in the simplicity of the treatment of the multiline transfer, which is useful since line overlapping due to the large velocities reached by the expanding matter is common in a SN envelope; the implicit incorporation of lineblocking of the radiation field, which allows photoionization rates to be calculated straightforwardly; and the possibility of including relativistic effects easily. The isotropy of the expansion in SN envelopes also allows for simplicity and efficiency of the optical depth integrations. The degree of selfconsistency of our code is such that only basic parameters are required as input, so that the synthetic spectra yield valuable information on essential SN parameters such as the bolometric luminosity, the photospheric velocity and the effective wavelength of line formation.
 Publication:

Astronomy and Astrophysics
 Pub Date:
 November 1993
 Bibcode:
 1993A&A...279..447M
 Keywords:

 Monte Carlo Method;
 Radiative Transfer;
 Stellar Envelopes;
 Stellar Models;
 Stellar Spectra;
 Supernovae;
 Computerized Simulation;
 Line Spectra;
 Mathematical Models;
 Photoionization;
 Photosphere;
 Stellar Luminosity;
 Astrophysics