Scientific Computing Seminar

Date:

Friday, May 28, 2004

Time:

1:00pm-2:00pm

Location:

50A-5132

Seminar Speaker:

Daniel Kasen
UCB/LBNL

Title:

Asymmetry and Polarization of Type Ia Supernovae

Abstract:

Recent polarization observations have shown that Type Ia supernovae (SNe Ia) are not perfectly spherical. The source of this asymmetry is likely closely tied to the supernova progenitor system and explosion physics; some possibilities include: instabilities in the nuclear burning front, an off-center deflagration-to-detonation transition, rapid rotation of the white dwarf, and/or the presence of a nearby companion star. For many of these scenarios, sophisticated numerical explosion simulations are now able to calculate the predicted 3-D ejecta distribution in some detail. To test the viability of such models, 3-D radiation transfer calculations are essential -- computing the synthetic spectra, polarization and lightcurves of the models allows us to directly confront them with observations. After a short review of recent SNe Ia observations, I will describe a 3-D Monte Carlo code developed to solve the polarized radiative transfer equation in expanding atmospheres. I will then present some applications of the code to study the observable consequences of asymmetries arising from a SN Ia interacting with a binary companion star. The models reveal how theoretically predicted asymmetries may play an important role in understanding the intrinsic dispersion in peak magnitudes and the "peculiar" spectral features observed in some SNe Ia.

Sponsor of Seminar:

Peter Nugent

Scientific Computing

Contact Esmond G. Ng EGNg@lbl.gov