Synchronized formation of starburst and poststarburst galaxies in merging clusters of galaxies

TL;DR

This paper presents numerical simulations showing that major cluster mergers can trigger synchronized star formation in gas-rich galaxies due to increased ICM pressure, leading to observable starburst and poststarburst populations.

Contribution

It introduces a new model linking cluster mergers to synchronized galaxy star formation and poststarburst transformation, supported by simulation data.

Findings

ICM pressure increases significantly during cluster mergers

Star formation is efficiently triggered by cold gas compression

Spatial distribution of poststarburst galaxies differs from other populations

Abstract

We propose that synchronized triggering of star formation in gas-rich galaxies is possible during major mergers of cluster of galaxies, based on new numerical simulations of the time evolution of the physical properties of the intracluster medium (ICM) during such a merger event. Our numerical simulations show that the external pressure of the ICM in which cluster member galaxies are embedded, can increase significantly during cluster merging. As such, efficient star formation can be triggered in gas-rich members as a result of the strong compression of their cold gas by the increased pressure. We also suggest that these star-forming galaxies can subsequently be transformed into poststarburst galaxies, with their spatial distribution within the cluster being different to the rest of its population. We discuss whether this possible merger-induced enhancement in the number of star-forming and post-star-forming cluster galaxies is consistent with the observed evolution of galaxies in merging clusters.