Constraining the Minimum Halo Mass that Supports Water Formation in a CCSN Remnant

TL;DR

This study uses simulations to determine the minimum minihalo mass capable of supporting water formation after Population III supernovae, finding that only halos above 10^6 solar masses can recollapse efficiently to enable water synthesis.

Contribution

It provides the first simulation-based lower mass limit for minihaloes that can support water formation post-supernova, highlighting the importance of host halo mass over stellar mass.

Findings

Minihaloes of mass 5×10^5 M⊙ do not support significant water formation.

Lower metallicity persists in the recollapsing core, limiting water synthesis.

Higher mass minihaloes (>10^6 M⊙) are more conducive to water formation.

Abstract

We present a simulation probing the formation of water in the remnant of low-mass Population III supernovae in a cosmological minihalo, and provide a tentative lower mass limit on host minihaloes that can recollapse on a short enough timescale and efficiently mix metals at high densities. We start from cosmological initial conditions and end the simulation when the central density undergoes catastrophic recollapse, whereby the water abundance is reported. During the Population III stars lifetime, the minihalo (M$ = 5 \times 10^5$ M$_{\odot}$) becomes blown out, and consequently the faint supernova explosion (E$_{\mathrm{SN}} = 5\times 10^{50}$ ergs) is completely unconfined to the virial radius of the minihalo. At the end of the simulation there is no significant water formation anywhere throughout the remnant, and the central recollapsing region is inefficient at incorporating the first metals into itself, remaining at low metallicity. The majority of metals are ejected from the core via bipolar outflow into the void and reach a peak metallicity of $\mathrm{Z} \sim 10^{-6}\ \mathrm{Z}_{\odot}$ at very low densities. The mass of the minihalo is low enough such that the recollapse timescale is unreasonable for this configuration to be the primary avenue of water formation in the early universe. We also provide a comparison with a regular CCSN (E$_{\mathrm{SN}} = 10^{51}$ ergs) and find the same effect, but amplified. As such, we can suggest that the minimum minihalo mass required for a confined explosion, and therefore the possibility of water formation is at least $10^{6}$ M$_{\odot}$ and the chemo-thermal evolution of a supernova remnant is more sensitive to the mass of the host minihalo than the mass of the Population III star residing within it.