What powers the starburst activity of NGC 1068? Star-driven gravitational instabilities caught in the act

TL;DR

This paper investigates how gravitational instabilities, driven by stars, fuel the intense starburst activity in NGC 1068, showing that these instabilities dominate over feedback processes and lead to molecular gas collapse.

Contribution

It demonstrates that stellar-driven gravitational instabilities are the primary mechanism behind starburst activity in NGC 1068, using diagnostic tools and multi-source data.

Findings

NGC 1068 is gravitationally unstable with powerful instabilities.

Star-driven instabilities dominate over feedback effects.

Coupling of stars and gas triggers molecular cloud collapse.

Abstract

We explore the role that gravitational instability plays in NGC 1068, a nearby Seyfert galaxy that exhibits unusually vigorous starburst activity. For this purpose, we use the Romeo-Falstad disc instability diagnostics and data from BIMA SONG, SDSS and SAURON. Our analysis illustrates that NGC 1068 is a gravitationally unstable "monster". Its starburst disc is subject to unusually powerful instabilities. Several processes, including AGN/stellar feedback, try to quench such instabilities from inside out by depressing the surface density of molecular gas across the central kpc, but they do not succeed. Gravitational instability "wins" because it is driven by the stars via their much higher surface density. In this process, stars and molecular gas are strongly coupled, and it is such a coupling that ultimately triggers local gravitational collapse/fragmentation in the molecular gas.