Trends in Dwarf Early-Type Kinematics with Cluster-centric Radius Driven By Tidal Stirring

TL;DR

This study models dwarf early-type galaxy dynamics in the Virgo cluster, showing that tidal stirring likely influences the observed radial trends in their rotational support, with simulations matching observational data.

Contribution

It demonstrates that tidal stirring can explain the observed radial dependence of dwarf galaxy kinematics in clusters, a novel insight into environmental effects.

Findings

Tidal stirring accounts for 34% of simulated gradients matching observations.

Models without environmental effects do not reproduce observed gradients.

Large scatter exists in the gradient of galaxy dynamics with radius.

Abstract

We model the dynamics of dwarf early-type galaxies in the Virgo cluster when subject to a variety of environmental processes. We focus on how these processes imprint trends in dynamical state (rotational vs. pressure support as measured by the $\lambda^*_{\rm Re/2}$ statistic) with projected distance from the cluster center, and compare these results to observational estimates. We find a large scatter in the gradient of $\lambda^*_{\rm Re/2}$ with projected radius. A statistical analysis shows that models with no environmental effects produce gradients as steep as those observed in none of the 100 cluster realizations we consider, while in a model incorporating tidal stirring by the cluster potential 34% of realizations produce gradients as steep as that observed. Our results suggest that tidal stirring may be the cause of the observed radial dependence of dwarf early-type dynamics in galaxy clusters.