An imaging polarimetry survey of Type Ia supernovae: are peculiar extinction and polarization properties produced by circumstellar or interstellar matter?

Abstract

Some highly reddened Type Ia supernovae (SNe Ia) display low total-to-selective extinction ratios (RV ≲ 2) in comparison to that of typical Milky Way dust (RV ≈ 3.3), and polarization curves that rise steeply to blue wavelengths, with peak polarization values at short wavelengths ($\lambda _{\rm max} < 0.4\, \mu$ m) in comparison to the typical Galactic values ($\lambda _{\rm max} \approx 0.55\, \mu$ m). Understanding the source of these properties could provide insight into the progenitor systems of SNe Ia. We aim to determine whether they are the result of the host galaxy’s interstellar dust or circumstellar dust. This is accomplished by analysing the continuum polarization of 66 SNe Ia in dust-rich spiral galaxies and 13 SNe Ia in dust-poor elliptical galaxies as a function of normalised galactocentric distance. We find that there is a general trend of SNe Ia in spiral galaxies displaying increased polarization values when located closer to the host galaxies’ centre, while SNe Ia in elliptical host galaxies display low polarization. Furthermore, all highly polarized SNe Ia in spiral host galaxies display polarization curves rising toward blue wavelengths, while no evidence of such polarization properties is shown in elliptical host galaxies. This indicates that the source of the peculiar polarization curves is likely the result of interstellar material as opposed to circumstellar material. The peculiar polarization and extinction properties observed toward some SNe Ia may be explained by the radiative torque disruption mechanism induced by the SN or the interstellar radiation field.

Diversity of Dust Properties in External Galaxies Confirmed by Polarization Signals from Type II Supernovae

“…The wavelength dependence of the ISP toward SN 2022aau deviates similarly from that of the MW as those toward some Type Ia SNe, i.e., the polarization peaks are at a shorter wavelength (  max l 4000 Å) than the typical ISP in the MW ( 5500 max l ~Å). This is evidence for the presence of non-MW-like dust in its host galaxy, implying a significantly enhanced abundance of small grains compared to MW dust, as suggested for dust in the host galaxies of reddened Type Ia SNe (e.g., Patat et al 2015;Chu et al 2022). This finding implies that such non-MW-like dust might be more common than expected in certain regions of galaxies, which might affect the picture of the star/planet formation in galaxies.…”

Linear and Circular Polarimetry of the Optically Bright Relativistic Tidal Disruption Event AT 2022cmc

“…The normalized Stokes q and u parameters were calculated following the standard approach as described in the FORS2 User Manual (Anderson 2015; see also Cikota et al 2017;Chu et al 2022):…”

Linear and circular polarimetry of the optically bright relativistic Tidal Disruption Event AT 2022cmc

“…The normalized Stokes q and u parameters were calculated following the standard approach as described in the FORS2 User Manual (ESO 2015, see also Cikota et al 2017, andChu et al 2022):…”