Locations and Morphologies of Jellyfish Galaxies in A2744 and A370

TL;DR

This study investigates the locations, environments, and morphologies of 13 ram-pressure stripped galaxies in two galaxy clusters at intermediate redshift, revealing their association with cluster mergers and their morphological disturbances.

Contribution

It provides new insights into the environmental dependence and morphological features of ram-pressure stripped galaxies in merging galaxy clusters at z~0.3-0.4.

Findings

Stripped galaxies in A370 are isolated infallers not associated with substructures.

Stripped galaxies in A2744 are within a high-velocity substructure linked to a cluster merger.

Stripped galaxies show significant morphological disturbances compared to the general cluster population.

Abstract

We present a study of the orbits, environments and morphologies of 13 ram-pressure stripped galaxies in the massive, intermediate redshift (z$\sim0.3-0.4$) galaxy clusters A2744 and A370, using MUSE integral-field spectroscopy and HST imaging from the Frontier Fields Program. We compare different measures of the locations and morphologies of the stripped sample with a sample of 6 poststarburst galaxies identified within the same clusters, as well as the general cluster population. We calculate the phase space locations of all cluster galaxies and carry out a substructure analysis, finding that the ram-pressure stripped galaxies in A370 are not associated with any substructures, but are likely isolated infalling galaxies. In contrast, the ram-pressure stripped galaxies in A2744 are strictly located within a high-velocity substructure, moving through a region of dense X-ray emitting gas. We conclude that their ram-pressure interactions are likely to be the direct result of the merger between two components of the cluster. Finally, we study the morphologies of the stripped and poststarburst galaxies, using numerical measures to quantify the level of visual disturbances. We explore any morphological deviations of these galaxies from the cluster population, particularly the weaker cases which have been confirmed via the presence of ionised gas tails to be undergoing ram-pressure stripping, but are not strongly visually disturbed in the broad-band data. We find that the stripped sample galaxies are generally divergent from the general cluster sample, with poststarburst galaxies being intermediary in morphology between stripped galaxies and red passive cluster members.