Evolution of the gas kinematics of galaxies in cosmological simulations

TL;DR

This study uses cosmological hydrodynamical simulations to analyze how galaxy gas kinematics evolve and how mergers and interactions contribute to the scatter in the Tully-Fisher relation, identifying the best velocity proxy for galaxy potential.

Contribution

It extends previous work by analyzing a broader simulated galaxy sample, highlighting the impact of mergers on kinematic scatter, and identifying the optimal velocity measure for galaxy potential.

Findings

Mergers and interactions increase Tully-Fisher scatter.

Kinematic indicators combining rotation and dispersion are more reliable.

Rotation velocity at the maximum of the rotation curve best proxies the potential well.

Abstract

We studied the evolution of the gas kinematics of galaxies by performing hydrodynamical simulations in a cosmological scenario. We paid special attention to the origin of the scatter of the Tully-Fisher relation and the features which could be associated with mergers and interactions. We extended the study by De Rossi et al. (2010) and analysed their whole simulated sample which includes both, gas disc-dominated and spheroid-dominated systems. We found that mergers and interactions can affect the rotation curves directly or indirectly inducing a scatter in the Tully-Fisher Relation larger than the simulated evolution since z=3. In agreement with previous works, kinematical indicators which combine the rotation velocity and dispersion velocity in their definitions lead to a tighter relation. In addition, when we estimated the rotation velocity at the maximum of the rotation curve, we obtained the best proxy for the potential well regardless of morphology.