On the role of non-circular motions in MaNGA galaxies I: global properties

TL;DR

This study systematically analyzes non-circular motions in 1624 MaNGA disk galaxies, revealing their dependence on stellar mass and their limited impact on overall galaxy rotation curves and the Tully-Fisher relation.

Contribution

It provides a large-scale, detailed analysis of non-circular motions in galaxies and assesses their influence on galaxy dynamics and scaling relations.

Findings

Non-circular motions range from 5% to 20% of circular rotation.

Low mass and late-type galaxies exhibit stronger non-circular motions.

Non-circular motions associated with spiral arms and bars minimally affect rotation curves.

Abstract

Non-circular (NC) motions represent the imprints of non-axisymmetric structures in galaxies, providing opportunities to study the physical properties of gas departing from circular rotation. In this work, we have conducted a systematic study of the non-circular motions in a sample of 1624 gas-rich disk galaxies from the MaNGA MPL-11. By using the H$\alpha$ velocity as a tracer of the disk rotation, we find indications that the amplitude of the non-circular motions is related to the stellar mass, with the low mass and late-type galaxies the most affected. In our sample, we find ratios of non-circular to circular rotation ranging from 5% to 20%. By implementing harmonic models to include NC motions associated with spiral arms and stellar bars, we find that the rotational curves traced with H$\alpha$ are barely affected by the NC induced by these structures. Consequently, in our sample, we do not find evidence that NC motions contribute to the scatter of the stellar Tully-Fisher relation. Our results suggest that non-circular motions might have a more localized effect in galaxies rather than a global one.