Jellyfish galaxy candidates in MACS J0717.5+3745 and thirty-nine other clusters of the DAFT/FADA and CLASH surveys

TL;DR

This study identifies and analyzes jellyfish galaxy candidates across 40 galaxy clusters, revealing their properties, distribution, and recent infall into clusters, with implications for understanding galaxy evolution in dense environments.

Contribution

First comprehensive catalog and analysis of jellyfish galaxy candidates in multiple clusters, highlighting their properties and spatial distribution.

Findings

81 candidates in MACS J0717 and 97 in other clusters.

Jellyfish candidates are mostly star-forming, blue, and have high SFRs.

Candidates tend to avoid the densest regions in MACS J0717.

Abstract

Galaxies in clusters undergo several phenomena such as ram pressure stripping and tidal interactions, that can trigger or quench their star formation and, in some cases, lead to galaxies acquiring unusual shapes and long tails. We searched for jellyfish galaxy candidates in a sample of 40 clusters from the DAFT/FADA and CLASH surveys covering the redshift range 0.2<z<0.9. In MACS J0717.5+3745 (MACS0717), our large spatial coverage and abundant sampling of spectroscopic redshifts allowed us to pursue a detailed analysis of jellyfish galaxy candidates in this cluster and its extended filament. We looked at the Hubble Space Telescope images of all the cluster galaxies (based on redshifts), and classified them as a function of their likeliness to be jellyfish galaxies, and give catalogues of jellyfish candidates with positions, redshifts, magnitudes, and projected distance to the respective cluster centre. We found 81 jellyfish candidates in the extended region around MACS0717, and 97 in 22 other clusters. Jellyfish galaxy candidates in MACS0717 tend to avoid the densest regions of the cluster, while this does not appear to be the case in the other clusters. For 79 galaxies in MACS0717 and 31 in other clusters, we computed the best stellar population fits with LePhare through the GAZPAR interface. We find that jellyfish candidates tend to be star forming objects, with blue colours, young ages, high star formation rates and specific star formation rates. In a SFR versus stellar mass diagram, jellyfish galaxy candidates appear to have somewhat larger SFRs than non-jellyfish star forming galaxies Based on several arguments, the jellyfish candidates identified in MACS0717 seem to have fallen rather recently into the cluster. A very rough estimate of the proportions of jellyfish galaxies in the studied clusters is about 10%.