Local instability signatures in ALMA observations of dense gas in NGC7469

TL;DR

This study uses ALMA observations to analyze the stability and local instability scales of dense gas in NGC7469, revealing a correlation between instability scales and star-forming regions.

Contribution

It provides the first detailed measurement of disc stability and instability scales in NGC7469 using dense gas tracers with high spatial resolution.

Findings

Disc stability parameter falls below unity where star formation is intense.

Measured instability scale (~180 pc) matches sizes of star cluster complexes.

Dense gas effectively traces regions of high-mass star formation.

Abstract

We present an unprecedented measurement of the disc stability and local instability scales in the luminous infrared Seyfert 1 host, NGC7469, based on ALMA observations of dense gas tracers and with a synthesized beam of 165 x 132 pc. While we confirm that non-circular motions are not significant in redistributing the dense interstellar gas in this galaxy, we find compelling evidence that the dense gas is a suitable tracer for studying the origin of its intensely high-mass star forming ring-like structure. Our derived disc stability parameter accounts for a thick disc structure and its value falls below unity at the radii in which intense star formation is found. Furthermore, we derive the characteristic instability scale and find a striking agreement between our measured scale of ~ 180 pc, and the typical sizes of individual complexes of young and massive star clusters seen in high-resolution images.