# Modeling C-Shock Chemistry in Isolated Molecular Outflows

## TL;DR

This paper enhances a chemical network model to better simulate shock-induced chemistry in molecular outflows, successfully reproducing observed molecular distributions and revealing new formation pathways for complex organic molecules.

## Contribution

The study introduces an improved shock-chemistry model incorporating high-temperature reactions and non-thermal desorption, providing new insights into molecule formation in shocked regions.

## Key findings

- Model reproduces observed molecular distributions in L1157
- Identifies new post-shock formation routes for certain COMs
- Suggests specific molecules as effective shock tracers

## Abstract

Shocks are a crucial probe for understanding the ongoing chemistry within ices on interstellar dust grains where many complex organic molecules (COMs) are believed to be formed. However, previous work has been limited to the initial liberation into the gas phase through non-thermal desorption processes such as sputtering. Here, we present results from the adapted three-phase gas-grain chemical network code NAUTILUS, with the inclusion of additional high-temperature reactions, non-thermal desorption, collisional dust heating, and shock-physics parameters. This enhanced model is capable of reproducing many of the molecular distributions and abundance ratios seen in our prior observations of the prototypical shocked-outflow L1157. In addition, we find that, among others, NH$_2$CHO, HCOOCH$_3$, and CH$_3$CHO have significant post-shock chemistry formation routes that differ from those of many other COMs observed in shocks. Finally, a number of selected species and phenomena are studied here with respect to their usefulness as shock tracers in various astrophysical sources.