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Recent photometric and polarimetric observations of type Ia supernovae (SNeIa) show unusually low total-to-selective extinction ratio ($R_{V}<2$) andwavelength of maximum polarization ($\lambda_{max}<0.4\mu m$) for several SNeIa, which indicates peculiar properties of interstellar (IS) dust in the SNhosted galaxies and/or the presence of circumstellar (CS) dust. In this paper,we use inversion technique to infer best-fit grain size distribution andalignment function of interstellar grains along the lines of sight toward fourSNe Ia with anomalous extinction and polarization data (SNe 1986G, 2006X,2008fp, and 2014J). We find that to reproduce low values of $R_{V}$, asignificant enhancement in the mass of small grains of radius $a< 0.1\mu m$ isrequired. For SN 2014J, a simultaneous fit to observed extinction andpolarization data is unsuccessful if the entire data is attributed to IS dust(model 1), but a good fit is obtained when accounting for the contribution ofCS dust (model 2). For SN 2008fp, our fitting results for model 1 show that, toreproduce an extreme value of $\lambda_{\max}\sim 0.15\mu m$, very smallsilicate grains must be aligned as efficiently as big grains. We suggest thattiny grains in the intervening molecular cloud can be aligned efficiently byradiative torques (RATs) from the SNe Ia. The resulting time dependencepolarization from this RAT alignment model can be tested by observing atultraviolet wavelengths. Our results are in favor of the existence of CS dustin SN 2014J, but its presence in SN 2008fp remains uncertain.

Properties and alignment of interstellar dust grains toward Type Ia Supernovae with anomalous polarization curves