Revisiting the formation of molecules and dust in core collapse supernovae

TL;DR

This study presents a new, exhaustive chemical model for a 15 M$_\odot$ core-collapse SN ejecta, applying a single reaction network to all regions to quantify molecule and dust-cluster yields up to ~11 years post-explosion. It identifies dominant molecular reservoirs (O$_2$, CO, SiS, SiO, CO$_2$, SO$_2$, CaS, N$_2$, CS) and shows dust is primarily silicates, silica, and carbon with limited alumina, while pure metal clusters are negligible. The results demonstrate that high-density clumps favor carbon-dust formation and that silicate/silica production requires warmer conditions; a low-temperature silicate regime suppresses dust yields significantly. The findings, consistent with recent JWST data, advance understanding of SN dust budgets and emphasize chemistry’s key role in shaping the dust output of supernovae in local and high-redshift galaxies.

Abstract

Context. Core-collapse Supernovae of Type II contribute the chemical enrichment of galaxies through explosion. Their role as dust producers in the high-redshift Universe may be of paramount importance. However, the type and amount of dust they synthesise after outburst is still a matter of debate and the formation processes remain unclear. Aims. We aim to identify and understand the chemical processes at play in the dust formation scenario, and derive mass yields for molecules and dust clusters at late post-explosion time. Methods. We revisit existing models by improving on the physics and chemistry of the supernova ejecta. We identify and consider new chemical species and pathways underpinning the formation of dust clusters, and apply a unique exhaustive chemical network to the entire ejecta of a Supernova with a 15 Msun progenitor. We test this new chemistry for various gas conditions in the ejecta, and derive mass yields for molecules and dust clusters. Results. We obtain the molecular component of the ejecta up to 11 years after explosion. The most abundant species are, in order of decreasing masses, O2, CO, SiS, SiO, CO2, SO2, CaS, N2, and CS. We identify molecules that are tracers of high-density clumps. As for dust clusters, we find the composition is dominated by silicates and silica, along with carbon dust, but with modest amounts of alumina. Pure metal clusters and metal sulphide and oxide clusters have negligible masses. High-density gas favours the formation of carbon clusters in the outer ejecta region whereas low temperatures hamper the formation of silicates in the oxygen core. The results are in good agreement with existing astronomical data and recent observations with the James Webb Space Telescope. They highlight the importance of chemistry for the derivation of dust budget from Supernovae.

Figures (22)

• Figure 1: Elemental composition as a function of enclosed mass for a Type II-P SN with 15 ${\rm M_{\odot}}$ progenitor from rau02.
• Figure 2: Zone velocity as a function of enclosed mass and zone position for the 15 ${\rm M_{\odot}}$ explosion model of rau02.
• Figure 3: Gas temperature for the ejecta regions defined in Table \ref{['par']} as a function of post-explosion time from koz98 except the O/C/Mg zone where values are from lil20. The label SC13 refers to the temperature profile used in sar13. The shaded area represents the temperature regime at which dust forms in dust-producing experiments in the laboratory (e.g. high-temperature flame or vapour condensation experiments).
• Figure 4: Mass fractions of molecules produced in the Si/S/Ca ejecta region at z=1.85 ${\rm M_{\odot}}$ as a function of post-explosion time for the Standard Case. The zone mass is $4.64 \times 10^{-3}$${\rm M_{\odot}}$.
• Figure 5: Total masses of molecules produced over the Si/S/Ca region as a function of post-explosion time for the Standard Case. The region mass is 0.111 ${\rm M_{\odot}}$ (see Table \ref{['par']}).