# Galaxy cluster mergers as triggers for the formation of jellyfish galaxies: case study of the A901/2 system

## TL;DR

This study models the complex merger of galaxy clusters A901/2 and links the formation of jellyfish galaxies to high ram pressure regions caused by gas interactions during the merger.

## Contribution

It introduces a hydrodynamic model of the A901/2 merger and suggests ram pressure stripping as a key mechanism for jellyfish galaxy formation in merging clusters.

## Key findings

- Jellyfish galaxies are located near gas boundary regions in the merger.
- Ram pressure increases by up to 1000 times, triggering gas loss.
- The model aligns with observed diffuse X-ray emission.

## Abstract

The A901/2 system is a rare case of galaxy cluster interaction, in which two galaxy clusters and two smaller groups are seen in route of collision with each other simultaneously. Within each of the four substructures, several galaxies with features indicative of jellyfish morphologies have been observed. In this paper, we propose a hydrodynamic model for the merger as a whole, compatible with its diffuse X-ray emission, and correlate the gas properties in this model with the locations of the jellyfish galaxy candidates in the real system. We find that jellyfish galaxies seem to be preferentially located near a boundary inside each subcluster where diffuse gas moving along with the subcluster and diffuse gas from the remainder of the system meet. The velocity change in those boundaries is such that a factor of up to $\sim$1000 increase in the ram pressure takes place within a few hundred kpc, which could trigger the high rate of gas loss necessary for a jellyfish morphology to emerge. A theoretical treatment of ram pressure stripping in the environment of galaxy cluster mergers has not been presented in the literature so far; we propose that this could be a common scenario for the formation of jellyfish morphologies in such systems.