Mitchell Institute for Fundamental Physics & Astronomy
College Station, Texas 77843
Spectropolarimetric observations of SNe Ia allow us to (i) study the geometry of the ejecta by observing the polarization of absorption lines, and (ii) study the dust along the line of sight to SNe Ia by observing the ISM continuum polarization. Understanding the effect of dust extinction on SNe Ia is essential for accurate measurement of cosmological parameters and the expansion history of the Universe. Different studies of the host galaxies dust extinction from SNe Ia yielded diverse values of the absorption to reddening ratio, Rv, ranging from Rv=1 to Rv=3.5 (see e.g. Cikota et al. 2016). Studies of dust along the lines of sight of SNe Ia might lead to conclusions on the progenitor system, because the single degenerate (SD) and double degenerate (DD) models imply different circumstellar environments. Furthermore, studeis of line polarization of SNe Ia might imply different explosion scenarios. Polarization models of SNe Ia predict different polarization signatures for the violent merger scenario, compared to the double-detonation and delayed-detonation models (Bulla et al. 2015, 2016). I will discuss the peculiar continuum polarization profiles of SNe Ia sight lines, and present preliminary line polarization results extracted from our spectropolarimetric observations of a sample of ~30 SNe Ia observed with VLT at more than 120 epochs in total.