Dust formation in Type IIn SNe

The source of the very large masses of dust observed in some very early Universe galaxies at redshifts z<6 has been much debated. Core-collapse supernovae (CCSNe) have been predicted to be efficient producers of dust but the majority have only had small masses of warm dust (<0.001 M⊙) detected in their ejecta during their early phases (t<3yr), based on fits to their near-IR and mid-IR SEDs. Observations in the far-IR with Herschel and ALMA have revealed far higher cold dust masses but there are currently no instruments capable of detecting cold SN dust in emission at extra-galactic distances. Dust formation in CCSNe often induces a red-blue asymmetry in the optical and NIR line profiles since redshifted radiation emitted from the receding half of the SN must traverse a higher column depth of dust to reach us. We present Monte Carlo radiative transfer models of dust-induced asymmetries in the optical and NIR line profiles of three interacting supernovae. We have used the Bayesian radiative transfer code DAMOCLES (Bevan & Barlow 2016; Bevan 2018) to model the Balmer and HeI lines of SN 2005ip, SN 2010jl and SN 1995N to determine the rate of dust formation and the current dust mass. We additionally constrain the clumping structure of the ejecta and properties of the dust grains. We compare our results to radiative transfer models of the optical-IR SEDs and consequently isolate the relative contributions to the IR flux from pre-existing circumstellar dust and newly-formed dust in the ejecta or cool, dense shell.