The Effects of Circumstellar Dust Scattering on the Light Curves and Polarizations of Type Ia Supernovae

TL;DR

This paper models how dust scattering in the circumstellar environment affects the light curves and polarization signals of Type Ia supernovae, highlighting the importance of polarimetric observations for detecting circumstellar dust.

Contribution

It introduces a Monte Carlo radiative transfer model considering various CSM geometries to analyze their effects on SN Ia observables, emphasizing the role of polarimetry.

Findings

Dust location influences light curve and color evolution.

Photometric data alone cannot reliably constrain CSM geometry.

Polarimetry over time can unambiguously detect circumstellar dust.

Abstract

Observational signatures of the circumstellar material (CSM) around Type Ia supernovae (SNe Ia) provide a unique perspective on their progenitor systems. The pre-supernova evolution of the SN progenitors may naturally eject CSM in most of the popular scenarios of SN Ia explosions. In this study, we investigate the influence of dust scattering on the light curves and polarizations of SNe Ia. A Monte Carlo method is constructed to numerically solve the process of radiative transfer through the CSM. Three types of geometric distributions of the CSM are considered: spherical shell, axisymmetric disk, and axisymmetric shell. We show that both the distance of the dust from the SN and the geometric distribution of the dust affect the light curve and color evolutions of SN. We found that the geometric location of the hypothetical circumstellar dust may not be reliably constrained based on photometric data alone, even for the best observed cases such as SN 2006X and SN 2014J, due to the degeneracy of CSM parameters. Our model results show that a time sequence of broadband polarimetry with appropriate time coverage from a month to about one year after explosion can provide unambiguous limits on the presence of circumstellar dust around SNe Ia.