Diverse lifestyles of bar-like galaxies and their coevolution with the brightest galaxy in the most massive cluster of TNG50

TL;DR

This study investigates the diverse formation and evolution pathways of bar-like galaxies in a massive cluster environment using the TNG50 simulation, highlighting their complex coevolution with brightest cluster galaxy progenitors.

Contribution

It provides detailed insights into the varied mechanisms and timelines of bar formation in cluster galaxies within a high-resolution cosmological simulation.

Findings

Most bars form during pericenter passages around BCG progenitors.

Bar lengths range between 2-6 kpc, not correlated with tidal forces.

Bar formation occurs over a wide timescale of 3-11 Gyr.

Abstract

Clusters can provide propitious environments for bar formation in galaxies. This work studies the formation and evolution of 15 bar-like galaxies in the most massive cluster of the TNG50 simulation from the IllustrisTNG suite. The selection includes galaxies from the last simulation output from well-resolved subhalos with a strongly prolate stellar component. Eleven galaxies form or strongly enhance their bars during a pericenter passage around one or more progenitors of the brightest cluster galaxy (BCG). Two form their bars early as a result of minor mergers, one via an interaction with another massive galaxy, and one via disk instability. The bar formation times differ considerably, ranging between 3-11 Gyr. The lengths of the bars also differ, ranging between 2-6 kpc, and do not correlate with the amount of tidal forcing experienced. All galaxies have at least one pericenter passage around a BCG progenitor, but the number of interactions varies strongly and is reflected in the different amount of mass stripping the galaxies experience. Most bar formation events take place before the BCG is fully formed. In three cases, they occur just before different progenitors of the BCG merge. For six bar-like galaxies, the merger events leading to the final formation of the BCG cause significant changes of their orbits. Their diverse evolutionary histories illustrate the different paths to bar formation in clusters and emphasize the complex nature of the process, which includes coevolution with BCG progenitors.