Establish the origin of enhanced gas-phase phosphorus in SNR shocks

Establish whether the enhanced PO⁺ abundance in molecular clouds impacted by the W44 and IC443 supernova-remnant shocks results from injection of phosphorus into the gas phase, processing of refractory phosphorus-bearing material, or redistribution of phosphorus among gas-phase chemical forms.

Background

The observations detect PO⁺ toward both supernova remnants but do not detect PN, while chemical models indicate that enhanced ionisation can shift phosphorus chemistry toward ionised species. These results do not identify whether the shocks add phosphorus to the gas or merely transform phosphorus already present in the cloud.

Resolving this issue is important for assessing whether supernova-remnant feedback enriches star-forming material with phosphorus or instead changes its chemical speciation. The distinction also bears on the proposed role of supernova-remnant shocks in supplying pre-biotic material to forming planetary systems.