Molecular Formation in Low-Metallicity Hot Cores

TL;DR

This study models how physical parameters, especially cosmic ray ionisation rate, influence molecular abundances in low-metallicity hot cores, aligning results with observations from the Large Magellanic Cloud.

Contribution

It introduces a detailed chemical model analyzing the impact of physical parameters on molecular evolution in low-metallicity hot cores, emphasizing the role of CRIR.

Findings

CRIR significantly affects molecular abundances.

Model matches observations at 10^5 years and specific CRIR.

Oxygen-bearing complex organic molecules may originate in different environments.

Abstract

The chemical complexity in low-metallicity hot cores has been confirmed by observations. We investigate the effect of varying physical parameters, such as temperature, density and the cosmic ray ionisation rate (CRIR), on the molecular abundance evolution in low-metallicity hot cores using the UMIST gas phase chemical model. CRIR had the strongest effect on molecular abundance. The resultant molecular abundances were divided into three categories with different trends in time evolution. We compared our results with the observations of hot cores in the Large Magellanic Cloud (LMC). Our model fits best with the observations at a time of around $10^5$ years after the evaporation of ice and at the CRIR of $1.36 \times 10^{-16}$ s$^{-1}$. The resultant abundances of the oxygen-bearing complex organic molecules (COMs), such as CH$_3$OH, HCOOCH$_3$ and CH$_3$OCH$_3$, do not fit with observations in the same physical condition and may be located in a different physical environment. Our results suggest that investigating the CRIR value is crucial to predict the molecular evolution in LMC hot cores.