Jellyfish galaxy candidates in MACS J0717.5+3745 and 39 other clusters of the DAFT/FADA and CLASH surveys

Context. Galaxies in clusters undergo several phenomena, such as RPS and tidal interactions, that can trigger or quench their star formation and, some cases, lead to galaxies acquiring unusual shapes long tails – become jellyfish. Aims. We searched for jellyfish galaxy candidates a sample of 40 from the DAFT/FADA CLASH surveys covering redshift range 0.2 < z 0.9. In MACS J0717.5+3745 (MACS0717), our large spatial coverage abundant sampling spectroscopic redshifts allowed us pursue detailed analysis this cluster its extended filament. Methods. retrieved NASA Extragalactic Database all (except MACS0717 which we had an extensive catalogue), looked at Hubble Space Telescope ACS images these objects (mainly F 606 W 814 bands), classified them function likeliness be galaxies. give catalogues with positions, redshifts, magnitudes, projected distance respective centre. For MACS0717, eight-magnitude optical infrared catalogue entire region compute best stellar population fits LePhare through GAZPAR interface. 31 other belonging survey, extracted up 17 magnitudes available fit spectral energy distribution same way. Results. found 81 around well 97 22 clusters. Jellyfish tend avoid densest regions cluster, while does not appear case The templates by show is occurring. Stellar masses are 10 9 ? 11 M ? , rates (SFRs) ?1 60 yr sample. Specific (sSFRs) notably higher more than half having values larger ?9 clusters, most have sSFR ?10 . populations younger (more age smaller 1.5 × yrs), following mid-infrared criteria, two may contain active galactic nucleus. SFR versus mass diagram, somewhat SFRs “non-jellyfish star-forming” mean 79 3.2 times star-forming non-jellyfish (selected log(sSFR) ? 11). Conclusions. Our objects, young ages blue colours. Based on arguments, identified seem fallen rather recently into cluster. A very rough estimate proportions studied about 10%; number vary strongly relaxation state, though result must confirmed data. represents basis future works.