| Abstract |
Polarization has been detected at early times for all types of
supernova, indicating that all such systems result from or quickly
develop some form of asymmetry. In addition, the detection of strong
line polarization in supernovae is suggestive of chemical
inhomogeneities (``clumps") in the layers above the photosphere, which
may reflect hydrodynamical instabilities during the explosion. We have
developed a fast, flexible, approximate semi-analytic code for modeling
polarized line radiative transfer within 3-D inhomogeneous
rapidly-expanding atmospheres. Given a range of model parameters, the
code randomly generates sets of clumps in the expanding ejecta and
calculates the emergent line profile and Stokes parameters for each
configuration. The ensemble of these configurations represents both the
effects of various host geometries and of different viewing angles. We
present results for the first part of our survey of model geometries,
specifically the effects of the number and size of clumps (and the
related effect of covering fraction) on the emergent spectrum and Stokes
parameters. We have also developed a method to connect the results of
our simulations to robust observational parameters such as maximum
degree of polarization and polarized flux throughout the line. Our
models, in connection with spectropolarimetric observations, can
constrain the 3-D structure of supernova ejecta and offer important
insight into the SN explosion physics and the nature of their progenitor
system.
This research was funded in part by the National Science Foundation
through grant AST-0807664. |