Polarized Line Profiles as Diagnostics of Circumstellar Geometry in Type IIn Supernovae.pdfVIP

To appear in “Circumstellar Media and Late Stages of Massive Stellar Evolution (2006)”RevMexAA(SC) POLARIZED LINE PROFILES AS DIAGNOSTICS OF CIRCUMSTELLAR GEOMETRY IN TYPE IIN SUPERNOVAE Jennifer L. Hoffman1,2 RESUMEN Favor de proporcionar un resumen en espa˜nol. If you cannot provide a spanish abstract, the editors will do this. Supernovae of type IIn possess spectral signatures that indicate an intense interaction 6 between the supernova ejecta and surrounding dense circumstellar material cast off by the star in pre-explosion 0 mass-loss episodes. Studying this interaction can yield clues to the nature of Type IIn progenitors and their 0 mass loss history. In particular, polarization spectra of Type IIn’s show complex line polarization and position 2 angle features that arise from a combination of geometrical and optical effects. I have constructed a Monte c Carlo code that simulates the transfer of the Hα line through circumstellar shells with various geometrical e D configurations and optical characteristics. The superposition of broad and narrow line components produced in different regions of the circumstellar environment and modified by electron and line scattering, hydrogen 0 absorption, thermal emission, and geometrical and viewing angle effects gives rise to a variety of polarized 1 line shapes in the model spectra. Comparison of these results with recent high-quality spectropolarimetric observations of Type IIn supernovae suggests that a model “shock” region between the supernova photosphere 1 v and the circumstellar shell is necessary to p