The Kinematic Morphology-Density Relation from the SAMI Pilot Survey

TL;DR

This study examines the relationship between galaxy kinematic types and local density in three clusters, revealing varied trends and suggesting different formation histories for slow rotators.

Contribution

It provides the first detailed analysis of the kinematic morphology-density relation across multiple galaxy clusters using SAMI data.

Findings

SR fraction increases with density in Abell 85

SRs are found on cluster outskirts

Different clusters show different density trends

Abstract

We present the kinematic morphology-density relation in three galaxy clusters, Abell 85, 168 and 2399, using data from the SAMI Pilot Survey. We classify the early-type galaxies in our sample as fast or slow rotators (FRs/SRs) according to a measured proxy for their projected specific stellar angular momentum. We find each cluster contains both fast and slow rotators with and average fraction of SRs in the sample of $f_{SR}=0.15\pm$0.04. We investigate this fraction within each cluster as a function of local projected galaxy density. For Abell 85 we find that $f_{SR}$ increases at high local density but for Abell 168 and 2399 this trend is not seen. We find SRs not just at the centres of our clusters but also on the outskirts and hypothesise that these SRs may have formed in group environments eventually accreted to the larger cluster.