Group pre-processing versus cluster ram-pressure stripping: the case of ESO156-G029

TL;DR

This study examines the effects of group pre-processing and ram-pressure stripping on galaxy ESO156-G029, revealing disturbed gas dynamics and predicting rapid evolution as it approaches the cluster center.

Contribution

It provides observational evidence of pre-processing and ram-pressure effects on a galaxy at the cluster's virial radius, proposing a scenario of its past merger and future evolution.

Findings

ESO156-G029 shows disturbed gas kinematics and asymmetric HI distribution.

The galaxy likely experienced a minor gas-rich merger in the past.

It is beginning to undergo ram-pressure effects, with rapid evolution expected near the cluster center.

Abstract

We report on observations of ESO156-G029, member of a galaxy group which is positioned at the virial radius of cluster Abell 3193. ESO156-G029 is located ~ 1.4 Mpc in projected distance from the brightest cluster galaxy NGC1500. We show that ESO156-G029 has disturbed gas kinematics and a highly asymmetric neutral hydrogen (HI) distribution, which are consequences of group pre-processing, and possibly of ram-pressure. Based on the current data we propose a scenario in which ESO156-G029 had a minor gas-rich merger in the past and now starts to experience ram-pressure. We infer that the galaxy will undergo rapid evolution once it gets closer to the cluster centre (less than 0.5 Mpc) where ram-pressure is strong enough to begin stripping the HI from the galaxy.