The influence of cosmic rays in the circumnuclear molecular gas of NGC1068

TL;DR

This study investigates how elevated cosmic ray ionization rates influence molecular composition in the circumnuclear disk of NGC1068, revealing that high cosmic ray flux significantly affects molecular abundances.

Contribution

It introduces a chemical model that accounts for high cosmic ray ionization rates to explain molecular observations in NGC1068's nucleus.

Findings

Most molecular species' column densities are better matched with high cosmic ray ionization.

The molecular gas in NGC1068 is heavily influenced by cosmic rays, about 1000 times the Milky Way rate.

External radiation fields also impact molecular chemistry in the galaxy's nucleus.

Abstract

We surveyed the circumnuclear disk of the Seyfert galaxy NGC1068 between the frequencies 86.2 GHz and 115.6 GHz, and identified 17 different molecules. Using a time and depth dependent chemical model we reproduced the observational results, and show that the column densities of most of the species are better reproduced if the molecular gas is heavily pervaded by a high cosmic ray ionization rate of about 1000 times that of the Milky Way. We discuss how molecules in the NGC1068 nucleus may be influenced by this external radiation, as well as by UV radiation fields.