The MAGPI Survey: Using kinematic asymmetries in stars and gas to dissect drivers of galaxy dynamical evolution

TL;DR

This study compares stellar and gas kinematic asymmetries in galaxies from MAGPI and SAMI surveys to understand the physical processes driving galaxy dynamical evolution, revealing differences related to stellar mass and age.

Contribution

It introduces a method to normalize kinematic asymmetries and compares these asymmetries across surveys, providing new insights into galaxy evolution mechanisms.

Findings

Stellar asymmetries are similar regardless of gas detection.

Anti-correlation between stellar asymmetry and stellar mass.

Older, star-forming galaxies show larger gas asymmetries.

Abstract

We present a study of kinematic asymmetries from the integral field spectroscopic surveys MAGPI and SAMI. By comparing the asymmetries in the ionsied gas and stars, we aim to disentangle the physical processes that contribute to kinematic disturbances. We normalise deviations from circular motion by $S_{05}$, allowing us to study kinematic asymmetries in the stars and gas, regardless of kinematic temperature. We find a similar distribution of stellar asymmetries in galaxies where we do and do not detect ionised gas, suggesting that whatever is driving the stellar asymmetries does not always lead to gas removal. In both MAGPI and SAMI, we find an anti-correlation between stellar asymmetry and stellar mass, that is absent in the gas asymmetries. After stellar mass and mean-stellar-age matching distributions, we find that at all stellar masses, MAGPI galaxies display larger stellar asymmetry compared to SAMI galaxies. In both MAGPI and SAMI galaxies, we find that star-forming galaxies with old mean-stellar-ages typically have larger asymmetries in their gas compared to their stars, whereas galaxies with young mean-stellar-ages have larger asymmetries in their stars compared to their gas. We suggest that this results from continuous, clumpy accretion of gas.