Optical Emission Line Nebulae in Galaxy Cluster Cores 1: The Morphological, Kinematic and Spectral Properties of the Sample

TL;DR

This study uses integral field spectroscopy to analyze the morphology, kinematics, and ionization of H-alpha emitting gas in 73 galaxy clusters, revealing mostly ordered gas dynamics and the influence of AGN activity.

Contribution

It provides a comprehensive kinematic and morphological analysis of ionized gas in galaxy cluster cores using VLT/VIMOS data, highlighting the prevalence of ordered gas motions and AGN disruption.

Findings

Majority of systems have ordered, disc-like gas kinematics

Over 50% of H-alpha flux is associated with ordered gas

Approximately 20% show disturbed morphologies due to AGN activity

Abstract

We present an Integral Field Unit survey of 73 galaxy clusters and groups with the VIsible Multi Object Spectrograph (VIMOS) on VLT. We exploit the data to determine the H$\alpha$ gas dynamics on kpc-scales to study the feedback processes occurring within the dense cluster cores. We determine the kinematic state of the ionised gas and show that the majority of systems ($\sim$ 2/3) have relatively ordered velocity fields on kpc scales that are similar to the kinematics of rotating discs and are decoupled from the stellar kinematics of the Brightest Cluster Galaxy. The majority of the H$\alpha$ flux ($>$ 50%) is typically associated with these ordered kinematics and most systems show relatively simple morphologies suggesting they have not been disturbed by a recent merger or interaction. Approximately 20% of the sample (13/73) have disturbed morphologies which can typically be attributed to AGN activity disrupting the gas. Only one system shows any evidence of an interaction with another cluster member. A spectral analysis of the gas suggests that the ionisation of the gas within cluster cores is dominated by non stellar processes, possibly originating from the intracluster medium itself.