A scaling-relation for disc galaxies: circular-velocity gradient versus central surface brightness

TL;DR

This paper establishes a scaling relation between the inner circular-velocity gradient and central surface brightness in disc galaxies, linking stellar density to the shape of the gravitational potential across diverse galaxy types.

Contribution

It introduces a new empirical scaling relation connecting velocity gradient and surface brightness, applicable to both luminous and low-surface-brightness galaxies.

Findings

d_{R}V(0) correlates with mu_{0} over large ranges

Central stellar density relates to the inner potential well shape

Applicable to dark matter dominated low-luminosity galaxies

Abstract

For disc galaxies, a close relation exists between the distribution of light and the shape of the rotation curve. We quantify this relation by measuring the inner circular-velocity gradient d_{R}V(0) for spiral and irregular galaxies with high-quality rotation curves. We find that d_{R}V(0) correlates with the central surface brightness mu_{0} over more than two orders of magnitude in d_{R}V(0) and four orders of magnitudes in mu_{0}. This is a scaling-relation for disc galaxies. It shows that the central stellar density of a galaxy closely relates to the inner shape of the potential well, also for low-luminosity and low-surface-brightness galaxies that are expected to be dominated by dark matter.