A tight N/O-potential relation in star-forming galaxies

TL;DR

This paper finds a stronger correlation between the nitrogen-to-oxygen ratio and the gravitational potential in star-forming galaxies, suggesting a more fundamental link to galaxy evolution than metallicity relations.

Contribution

It demonstrates a tighter N/O versus gravitational potential relation, highlighting its significance over metallicity in understanding galaxy chemical evolution.

Findings

N/O correlates more tightly with gravitational potential than metallicity.

Deeper potential wells resist metal outflows and relate to star formation history.

N/O is less affected by metal-poor inflows, making it a robust evolutionary indicator.

Abstract

We report a significantly tighter trend between gaseous N/O and $M_*/R_e$ (a proxy for gravitational potential) than has previously been reported between gaseous metallicity and $M_*/R_e$, for star-forming galaxies in the MaNGA survey. We argue this result to be a consequence of deeper potential wells conferring greater resistance to metal outflows while also being associated with earlier star-formation histories, combined with N/O being comparatively unaffected by metal-poor inflows. The potential-N/O relation thus appears to be both more resistant to short-timescale baryonic processes and also more reflective of a galaxy's chemical evolution state, when compared to previously-considered relations.