Dust formation and evolution in the ejecta of core-collapse supernovae

Observations of local supernovae over the past couple of decades have reported the presence of dust in the ejecta. The dust masses inferred from observations in mid-infrared and submillimeter wavelengths differ by a factor of 10^2 to 10^4 The composition of dust in the ejecta is yet to be determined with precision. The reddening of the high redshift quasars also indicate the presence of large masses of dust in the early galaxies, the source of which is not yet clear. The sizes of the dust grains in the ejecta control their probability of survival against the reverse-shock(s) in the remnant phase and their contribution to the total dust budget of the galaxy. Core-collapse supernovae and AGB stars are the most important sources of dust in a given galaxy, however their relative contributions are still uncertain.
This project aims to quantify the role of core-collapse supernovae as dust producers in the galaxy. I study the production of dust in Type II-P supernova ejecta by coupling the gas-phase chemistry to the dust nucleation and condensation phases using a chemical kinetic approach. Several supernova progenitor masses with homogeneous and clumpy ejecta is assessed to estimate the chemical type and quantity of dust formed. Grain size distributions are derived for all dust components as a function of post-explosion time. The obtained dust properties are used to calculate the spectral energy distributions which are then compared to the estimated fluxes from SN1987A. The chemistry of the gas-phase and the simultaneous formation of dust clusters are described by a chemical network that includes all possible processes efficient at high gas temperatures and densities. The formation of key bimolecular species (e.g., CO, SiO) and dust clusters of silicates, alumina, metal carbides and sulphides, pure metals, and amorphous carbon is considered.
The findings suggest the formation of dust in the ejecta with final masses between 0.3-0.14 Mʘ depending on the physical conditions. Silicates, alumina and amorphous carbon stand out as the leading dust components. The grain size distributions are slewed towards large grains, and differ from the usual Mathis, Rumpl & Nordsieck power-law distribution characterising interstellar dust. An increase in the degree of clumpiness and a decrease in the amount of radioactive 56^Ni induce an early formation of dust leading to larger dust mass and bigger grains (~ 0.1-1 μm). These grains are most likely to survive the shock phases and enrich the dust budget of the galaxy. The mass of the progenitor dictates the relative abundances C-rich and O-rich dust components. Our results highlight the fact that dust synthesis in Type II-P supernovae is not a single and simple process, as it is often assumed. They confirm the total dust mass gradually builds up over a time span of ~ 5 years post-outburst, and provide a genuine explanation for the discrepancy between the small amounts of dust formed at early post-explosion times and the large dust masses derived from recent observations of supernova remnants.