The MAGPI Survey: the subtle role of environment and not-so-subtle impact of generations of stars on galaxy dynamics

The stellar age and mass of galaxies have been suggested as the primary determinants for the dynamical state of galaxies, with environment seemingly playing no or only a very minor role. We use a sample of 77 galaxies at intermediate redshift (z ∼ 0.3) in the Middle-Ages Galaxies Properties with Integral field spectroscopy (MAGPI) Survey to study the subtle impact of environment on galaxy dynamics. We use a combination of statistical techniques (simple and partial correlations and principal component analysis) to isolate the contribution of environment on galaxy dynamics, while explicitly accounting for known factors such as stellar age, star formation histories, and stellar masses. We consider these dynamical parameters: high-order kinematics of the line-of-sight velocity distribution (parametrised by the Gauss-Hermite coefficients h₃ and h₄), kinematic asymmetries V_asym derived using KINEMETRY, and the observational spin parameter proxy λRe . Of these, the mean h₄ is the only parameter found to have a significant correlation with environment as parametrised by group dynamical mass. This correlation exists even after accounting for age and stellar mass trends. We also find that satellite and central galaxies exhibit distinct dynamical behaviours, suggesting they are dynamically distinct classes. Finally, we confirm that variations in the spin parameter λRe
are most strongly (anti-)correlated with age as seen in local studies, and show that this dependence is well-established by z ∼ 0.3.