Polarimetric Studies Galaxies

Photopolarimetry provides unique insights into the composition, structure, and physical properties of interstellar dust in galaxies. This thesis presents an extensive polarimetric analysis of supernova host galaxies, focusing on interstellar polarization (ISP), dust extinction properties, and the alignment of magnetic fields. Within dust environments light can be polarized by scattering off dust grains or by absorption of spheroidal grains aligned by an external magnetic field. Radiative transfer simulations were realized to provide expectations for the polarization of light due to scattering off different types of dust environments.

Observations were conducted using VLTFORS2 polarimetric imaging, and a robust data reduction sequence was developed to correct instrumental and interstellar polarization effects. The results confirm the presence of an axisymmetric scattering pattern in multiple galaxies of our sample, with a stronger effect in blue bands. Additionally, the wavelength dependence of polarization follow either a U-shape or a monotonic increase, in scattering-dominated regions, aligning with simulations for graphite and silicate grains, respectively. Some observed polarization angle maps reveal alignment with spiral arms, supporting theoretical predictions of magnetic field orientation.

The Serkowski relation is confirmed in several regions, allowing for precise determinations of the peak wavelength (λmax) and total-toselective extinction ratio (RV). These parameters exhibit spatial variations, with RV being on average similar to that of the Milky Way ~3.1 in mid and outer regions of host galaxies but displaying variations between arm and inter-arm regions. Milky Way ISP estimations align well with Planck observations, though with notable differences in angle. Statistical comparisons indicate that polarization, and in a few particular cases RV, distributions vary across different galaxies, emphasizing the complex interplay between dust grain properties and local interstellar environments. These findings contribute to an expanded understanding of dust-induced polarization in intragalactic environments.