Cluster passage driving galaxy kinematic and structural evolution in the SAMI Galaxy Survey

TL;DR

This study investigates how galaxy passage through clusters affects their stellar and gas kinematics, revealing increased disturbances and structural changes in cluster environments, especially for recent infallers and those in complex substructures.

Contribution

It provides new insights into the impact of cluster environments on galaxy kinematic asymmetries and star formation distribution, using SAMI survey data to analyze the effects of ram pressure stripping.

Findings

Higher fraction of gas asymmetries in cluster galaxies

Recent infallers show more disturbed kinematics

Cluster substructure correlates with increased asymmetries

Abstract

The cluster environment can have a significant impact on galaxy evolution. We study the impact that passage through a cluster has on stellar and ionised gas kinematics for galaxies within the Sydney-AAO Multi Integral field (SAMI) Galaxy Survey. We compute the kinematic asymmetry $v_{\rm asym}$ in the line-of-sight stellar and ionsied gas velocity maps to quantify how the cluster environment disturbs the kinematics of the stars and ionised gas. We find a significantly higher fraction of galaxies with elevated gas asymmetries in clusters compared to non-cluster environments (17$^{+2}_{-3}$\%, 26/154 vs. 11$^{+1}_{-1}$\%, 72/751), with these galaxies most likely being recent infallers passage based on their position in projected-phase-space. Compared to cluster galaxies without elevated gas asymmetries, cluster galaxies with elevated gas asymmetries have, on average, more centrally concentrated star-formation. Finally, we find the highest fraction of galaxies with elevated gas asymmetries in clusters likely to host significant substructure or be dynamically complex. Our findings are consistent with the scenario of galaxies falling into clusters, either individually or in groups, and undergoing disk-fading and a redistribution of gas, due to ram pressure stripping experienced during pericentre passage.