Jellyfish galaxy candidates in MACS J0717.5+3745 and thirty-nine other clusters of the DAFT/FADA and CLASH surveys
Florence Durret, Simon Chiche, Catarina Lobo, Mathilde Jauzac
AAstronomy & Astrophysics manuscript no. aanda ©ESO 2021February 5, 2021
Jellyfish galaxy candidates in MACS J0717.5+3745 and 39other clusters of the DAFT/FADA and CLASH surveys
F. Durret , S. Chiche , C. Lobo , , and M. Jauzac , , , (cid:63) Sorbonne Université, CNRS, UMR 7095, Institut d’Astrophysique de Paris, 98bis Bd Arago, 75014, Paris, France Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, CAUP, Rua das Estrelas, PT4150-762 Porto,Portugal Departamento de Física e Astronomia, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre 687,PT4169-007 Porto, Portugal Centre for Extragalactic Astronomy, Durham University, South Road, Durham DH1 3LE, UK Institute for Computational Cosmology, Durham University, South Road, Durham DH1 3LE, UK Astrophysics Research Centre, University of KwaZulu-Natal, Westville Campus, Durban 4041, South Africa School of Mathematics, Statistics & Computer Science, University of KwaZulu-Natal, Westville Campus, Durban4041, South Africa
ABSTRACT
Context.
Galaxies in clusters undergo several phenomena, such as ram pressure stripping and tidal interactions, thatcan trigger or quench their star formation and, in some cases, lead to galaxies acquiring unusual shapes and long tails- some become jellyfish.
Aims.
We searched for jellyfish galaxy candidates in a sample of 40 clusters from the DAFT/FADA and CLASHsurveys covering the redshift range . < z < . . In MACS J0717.5+3745 (MACS0717), our large spatial coverage andabundant sampling of spectroscopic redshifts allowed us to pursue a detailed analysis of jellyfish galaxy candidates inthis cluster and its extended filament. Methods.
We retrieved galaxy spectroscopic redshifts in the NASA Extragalactic Database for galaxies in all the clustersof our sample (except for MACS0717 for which we had an extensive catalogue), looked at the Hubble Space TelescopeACS images of these objects (mainly the F606W and F814W bands), and classified them as a function of their likelinessto be jellyfish galaxies. We give catalogues of jellyfish galaxy candidates with positions, redshifts, magnitudes, andprojected distance to their respective cluster centre. For MACS0717, an eight-magnitude optical and infrared cataloguecovering the entire region allowed us to compute the best stellar population fits with LePhare through the GAZPARinterface. For the 31 jellyfish candidates in the other clusters belonging to the CLASH survey, we extracted up to 17magnitudes available in the CLASH catalogues to fit their spectral energy distribution in the same way.
Results.
We found 81 jellyfish galaxy candidates in the extended region around MACS0717 as well as 97 in 22 otherclusters. Jellyfish galaxy candidates in MACS0717 tend to avoid the densest regions of the cluster, while this does notappear to be the case in the other clusters. The best fit templates found by LePhare show that star formation is occurring.Stellar masses are in the range − M (cid:12) , and the star formation rates (SFRs) are in the − − M (cid:12) yr − range for MACS0717 and in the − − M (cid:12) yr − range for the other sample. Specific star formation rates (sSFR)are notably higher in MACS0717, with more than half of the sample having values larger than − yr − , while in theother clusters, most galaxies have sSFR < − yr − . Stellar populations appear younger in MACS0717 (more thanhalf have an age smaller than . × yrs), and following mid-infrared criteria two galaxies may contain an AGN. In aSFR versus stellar mass diagram, jellyfish galaxy candidates appear to have somewhat larger SFRs than “non-jellyfishstar forming” galaxies. For MACS0717, the mean sSFR of the 79 jellyfish galaxy candidates is 3.2 times larger thanthat of star-forming non jellyfish galaxies (selected with log(sSFR) ≥ − ). Conclusions.
Our jellyfish galaxy candidates are star forming objects, with young ages and blue colours. Based on severalarguments, the jellyfish candidates identified in MACS0717 seem to have fallen rather recently into the cluster. A veryrough estimate of the proportions of jellyfish galaxies in the studied clusters is about 10%, and this number does notseem to vary strongly with the cluster relaxation state, though this result must be confirmed with more data. Oursample of 97 galaxies in 22 clusters represents the basis of future works.
Key words. clusters: galaxies, clusters: individual: MACS J0717+3745, galaxies: star formation
1. Introduction
Due to the high density of galaxies found in clusters andto the presence of hot X-ray emitting gas, cluster galaxies (cid:63)
Based on archive data of the Hubble Space Telescope. Thispaper has made use of the NASA Extragalactic Database andof the GAZPAR tool to apply the LePhare software. are subject to environmental mechanisms that do not af-fect significantly their field counterparts. The most impor-tant ones are ram pressure stripping (Gunn & Gott 1972),hereafter RPS, which affects the gas contained in galaxies,and tidal effects which affect both gas and stars and oftenlead to harrassment (Moore et al. 1996). A nice summaryof all the physical processes taking place in clusters can be
Article number, page 1 of 44 a r X i v : . [ a s t r o - ph . GA ] F e b &A proofs: manuscript no. aanda found in e.g. the introduction of Poggianti et al. (2017b) andwill not be repeated here. We will here concentrate on thedescription of observations performed these last 15 yearsby various teams. Galaxies with unusual shapes and starforming properties have been found in many galaxy clus-ters, mostly at optical wavelengths, but with some features(mainly long tails) that are also sometimes detected in X-rays and/or at radio wavelengths. The number and depthof analyses of such objects have been increasing tremen-dously these last few years, in particular with the advent ofVLT/MUSE (see below). To our knowledge, the first one toname some of these objects « jellyfish galaxies » was Bekki(2009).Owen et al. (2006) studied the very rich merging clus-ter Abell 2125 (z=0.247) at several wavelengths, and foundgalaxy C153 showing an X-ray plume with [OII] emis-sion in knots, interpreted as due to ram pressure strip-ping. The spectral energy distribution (SED) of C153 showsthat it has undergone continuous star formation for 3.5Gyr, further supporting that it can be considered a proto-type jellyfish galaxy, even if not named as such. Sun et al.(2007) found ESO137-001 in the massive cluster Abell 3627(z=0.01625) with a 40 kpc H α tail coinciding with a 70 kpcX-ray tail. The H α emission of the galaxy itself is sharplytruncated, and 49 emission line knots are distributed alongthe tail over 39 kpc. These authors attribute the originof the tail to ram pressure stripping, and mention thatheat conduction may contribute to the energy of the op-tical lines. Cortese et al. (2007) found two peculiar galaxiesfalling into the massive galaxy clusters Abell 1689 (z =0.18) and Abell 2667 (z = 0.23). Their Hubble Space Tele-scope ( HST ) images show extraordinary trails composed ofbright blue knots (with absolute magnitudes in the range − . < M < − . ) and stellar streams associated witheach of these systems, one of them experiencing a strongburst of star formation (SF) while the other has recentlyceased its SF activity. They interpret these results as dueto the combined action of tidal interaction with the clusterpotential and ram pressure stripping. Yoshida et al. (2008)detected a string of "fireballs" (star-forming clouds with alinear stream of young stars extending towards the galaxy,detected in H α ) in the Coma cluster, "hanging" from galaxyRB 199. They showed that tidal effects alone could notaccount for the formation of such fireballs while the rampressure stripping mechanism could provide a good expla-nation. In the optical and UV, Smith et al. (2010) observed13 asymmetric star forming galaxies in the Coma cluster,due to star formation from the gas stripped from the galax-ies by interaction with their environment, and long tailsreaching 100 kpc. Also in Coma, Yagi et al. (2010) foundextended H α clouds in 14 galaxies at the edges of the clus-ter, suggesting that the parent galaxies have a large velocitywith respect to the Coma cluster.Rawle et al. (2014) analysed star formation in 53 galax-ies of Abell 2744 (z=0.308), including some jellyfish galax-ies. They found that the orientations of the trails, and of thematerial stripped from constituent galaxies, indicated thatthe passing shock front of the cluster merger was the trigger.Ebeling et al. (2014) searched for extreme cases of jellyfishgalaxies at z > . with HST
Snapshots, and found six verybright objects with M F606W < − . They proposed a clas-sification of jellyfish galaxies, from J=1 (mildly affected) toJ=5 (very strongly affected) that is now commonly used.This paper was followed by several others. McPartland et al. (2016) studied 63 MACS clusters, and found many morejellyfish galaxies (but with no measured redshifts), showingthe presence of optical tails. Their comparison to a simplemodel showed that extreme RPS events are associated tocluster mergers rather than to infall along filaments, eventhough these do occur too. Kalita & Ebeling (2019) then de-tected a showcase jellyfish galaxy in Abell 1758N and anal-ysed it in detail, with [OII] emission up to 40 kpc. Ebeling& Kalita (2019) analysed the field of Abell 1758N (z=0.28)and detected 8 RPS jellyfish candidates undergoing intenseSF.The first paper describing observations of jellyfish galax-ies with VLT/MUSE was that of Fumagalli et al. (2014)on ESO 137-001 (z=0.01625). They detected a double tailreaching 80 kpc, seen previously in X-rays, and inferredthat the galaxy is falling radially into the massive Normacluster. A complementary study with APEX (Jáchym et al.2014) had already uncovered an exceptionally long molec-ular tail in this galaxy; follow-up observations with ALMA(Jáchym et al. 2019) allowed detecting, for the first time,the molecular gas at the heads of several "fireballs" locatedin the complex tail structure of this spectacular galaxy.Poggianti et al. (2016) published the first analysis ofseveral hundred jellyfish galaxies at low redshift, based onthe WINGS + OMEGAWINGS sample, selecting galax-ies with various asymmetric/disturbed morphologies andknots, suggestive of triggered SF. This team then obtaineda large observing program on VLT/MUSE : the GAs Strip-ping Phenomena survey (GASP, Poggianti et al. 2017b). Inthis first paper of a long series, they show MUSE results onthe massive galaxy JO206 (z=0.0513), which is undergoingRPS in a poor cluster and shows a 90 kpc tail. This paperhas been followed by many others, out of which we onlyquote a few. Bellhouse et al. (2019) analysed the 94 kpc longtails of JO201 in Abell 85. George et al. (2019) analysed thegalaxy JO201 and showed that this galaxy, which is fallinginto Abell 85, is located close to the cluster centre, andundergoes both RPS and AGN feedback. Radovich et al.(2019) analysed seven jellyfish galaxies and highlighted theimportance of outflows. Poggianti et al. (2019) achieved avery complete study of JW100 with MUSE and also ALMA,VLA, UVIT, and Chandra , and studied the influence of gasstripping, gas heating and AGN. They propose that ISMheating due to interaction with the intracluster mediumis responsible for the X-ray tail. Moretti et al. (2020) anal-ysed ALMA observations of the jellyfish galaxy JW100, anddetected a large amount of molecular gas, 30% of which islocated in the stripped gas tail out to 5 kpc from the galaxycenter. They interpreted this molecular gas, which withinthe disk is totally displaced relatively to the stellar com-ponent, as newly born from stripped HI gas or recentlycondensed from stripped diffuse molecular gas.Another interesting result of the GASP survey, obtainedto our knowledge for the first time, is that found by Vulcaniet al. (2019), who observed four field galaxies with increasedSF and tattered H α , making them appear similar to someof our jellyfish galaxies, although they are not membersof any cluster. They attributed this increased SF to theeffect of cosmic web filaments (none of the galaxies is in acluster, three are in small groups, and all are embedded ina filament).At higher redshift, VLT/MUSE results were also ob-tained by Boselli et al. (2019), who undertook a spectro-scopic survey at redshift 0.25 < z < 0.85 in groups and clus- Article number, page 2 of 44. Durret et al.: Jellyfish galaxy candidates in medium redshift clusters ters (the MAGIC survey: MUSE gAlaxy Groups In Cosmos,Epinat et al., in prep.). They detected two star-forminggalaxies in the COSMOS cluster CGr32 at z = 0.73 withtwo extended (up to ∼ kpc in projected distance) tailsof ionised gas without any stellar counterpart in the deepoptical images.All these studies are devoted to the observations ofrather small numbers of jellyfish galaxies per cluster. On theother hand, Roman-Oliveira et al. (2019) observed a largenumber of jellyfish galaxies (73, out of which they discardedthree that were probably interacting galaxies) in a singlezone: the multi-cluster system Abell 901/902 (z=0.165). Inparticular, they showed that the starburst phenomenon in-creases with jellyfish class.As far as numerical simulations on these specific objectsare concerned, Bekki (2009) made hydrodynamical simu-lations to study the effect of RPS on galaxies in clustersand, to our knowledge, was the first to use the term « jel-lyfish ». His simulated galaxies look very much like thejellyfish galaxies that are observed. More recently, Rug-giero et al. (2019) published hydrodynamical simulationsto model the four structures observed in Abell 901/902 byRoman-Oliveira et al. (2019). They showed that many (butnot all) jellyfish galaxies are located in the vicinity of rampressure boundaries, defined as regions where gas movingalong each subcluster and gas from the remainder of thesystem meet. Galaxies become jellyfish when they cross aboundary within their parent subcluster, where a signifi-cant pressure increase takes place, due to the merging ofthe cluster gas and subcluster gas. A significant amount ofjellyfish galaxies must be created by this mechanism. Wecan also mention the model by Safarzadeh & Loeb (2019)accounting for SF due to RPS. According to their results,jellyfish galaxies must be late infallers for their model towork, and they predict no jellyfish galaxies to be present atshort clustercentric distances (smaller than (0.3-0.4) R ,see their Fig . 3).We present here a search for jellyfish galaxy candidatesin HST images available for clusters of the DAFT/FADA and CLASH surveys. Though a number of such objectshave been detected and thoroughly analysed these last years(as discussed before), the number of jellyfish galaxies atmedium redshift is still limited, and our aim here is to in-crease this number in the redshift range . < z < . . Forthe cluster MACS J0717.5+3745 (hereafter MACS0717) wehave a large spectroscopic redshift catalogue that allows usto search for jellyfish galaxies not only in the cluster corebut also in its extended filament (Jauzac et al. 2012, 2018b;Durret et al. 2016; Martinet et al. 2016). This will allow adetailed study of the distribution of jellyfish galaxy candi-dates in this extended environment. For the other clusters,our method will not allow us to make a statistical studysince the redshift coverage of the clusters is by no meanscomplete, but it is a first step towards the study of theseinteresting objects, in particular those at relatively highredshift, and therefore closer to the redshift of cluster for-mation. The list of new jellyfish galaxy candidates proposedhere will hopefully be exploited later at various wavelengthsby us or others.The paper is organized as follows. We describe our initialsample of 40 clusters and the method we apply in Section 2. http://cesam.lam.fr/DAFT/index.php https://archive.stsci.edu/prepds/clash/ We give our catalogue of 81 jellyfish candidates in the ex-tended region of MACS0717 in Section 3, and discuss theirspatial distribution and colour. The 97 jellyfish candidatesin 22 other clusters (there are 17 clusters in which we foundno jellyfish galaxy) are presented in Section 4. The spectralenergy distribution and derived quantities (such as stellarmass, star formation rate, etc.) of all the jellyfish candi-dates are analysed in Section 5. Finally, we summarise anddiscuss our results and propose some conclusions in Sect. 6.All distances are computed with Ned Wright’s calcu-lator , assuming H = 70 km s − Mpc − , Ω Λ = 0 . and Ω m = 0 . . Magnitudes are quoted in AB system.
2. Galaxy sample and identification of jellyfishcandidates
We have considered 40 clusters from the DAFT/FADA andCLASH surveys, which were all selected to be massive clus-ters (M > × M (cid:12) for DAFT/FADA, and kT > keV,corresponding to a mass in the (5 − × M (cid:12) range, forCLASH). For all clusters except MACS0717, we retrievedfrom NED all galaxy spectroscopic redshifts available inthe regions covered by the HST images. The cluster listis given in Table 1. The cluster redshift range covered is . ≤ z ≤ . . For MACS0717, the large spectroscopicredshift catalogue available covers not only the cluster corebut its extended filament as well, so we dedicate an impor-tant part of this paper to its study. The redshift coveragein most clusters is quite homogeneous.For each cluster, we identify galaxies with spectroscopicredshifts in the range previously chosen to draw galaxy den-sity maps (Durret et al. 2016, 2019), and roughly corre-sponding to an interval of ± . around the correspondingcluster redshift. This translates into a velocity range in-dicated in Table 1 for each cluster, expressed in units ofthe corresponding cluster velocity dispersion (computed inSection 2.3). We can thus see that the redshift interval firstchosen by Durret et al. (2016) is somewhat limited in somecases, and could make us miss fast moving galaxies. In par-ticular for MACS0717, to which a large part of this paper isdedicated, this strategy would limit our analysis to a rangeof ± . σ v (see Fig. 5 of Durret et al. (2016), initial value).We thus decided to extend the redshift interval of this clus-ter to ± σ v (final value reported in the same Table), thesole system where we have a large enough spectroscopic andspatial coverage allowing for a more detailed analysis thanwhat is possible for the remaining clusters.Two of us (FD and SC) separately looked at each of theselected galaxies, searching for objects that could be classi-fied as jellyfish galaxy candidates, based on several criteria:asymmetry, tidal arms, star trails. We independently clas-sified them between J=1 and J=5 according to their prob-ability of being a jellyfish, as suggested by Ebeling et al.(2014): J=1 being the smallest confidence index and J=5the largest. In most cases, our classifications agreed within ± , but we prefer to give both classifications, in Tables 2and 3, to illustrate the relative difficulty of eye classifica-tion. We nonetheless favored eye classification since jellyfishgalaxies cover a large variety of shapes, making it difficult https://ned.ipac.caltech.edu/ Article number, page 3 of 44 &A proofs: manuscript no. aanda to automatize their identification. Out of the 40 clustersconsidered, there were 17 in which we detected no jellyfishcandidate. This is probably due to the fact that in someclusters we only have a small number of redshifts withinthe imaged area, and in those clusters none of the galax-ies with a measured redshift entered this category. We aretherefore left with a sample of jellyfish candidates in 22cluster fields (besides MACS0717).To visually identify jellyfish galaxies, we used HST im-ages. All clusters apart from Cl0152.7-1357 have data inthe F814W filter. Whenever possible, we also consideredimages in the F606W filter as well, to compare the aspectof the galaxies in both filters. Sometimes, F606W imageswere not available, so we considered another filter, as indi-cated in Table 3. When possible, we show for each galaxyits images in two filters (with the bluer image to the left andthe redder to the right, at the same scale, see Appendix). Insome cases, fields covered by the two filters are not exactlythe same, so even if a cluster is observed in two filters, anindividual galaxy may be found only in one image. In suchcases, as well as for clusters observed in a single band, onlyone image is shown. For a very small number of cases, theastrometries of the two
HST images are slightly different,so images look a little displaced.However, we must keep in mind that clusters in our sam-ple cover a rather large redshift range, so the rest-framewavelengths corresponding to the filters analysed are notall the same. For MACS0717 (z=0.5458), the central wave-lengths of F606W and F814W filters correspond to rest-frame wavelengths of 392 and 527 nm respectively. At theextreme redshifts of our sample, at z=0.2, the central wave-lengths of F606W and F814W filters correspond to rest-frame wavelengths of 505 and 678 nm respectively, whileat z=0.9 they correspond to rest frame wavelengths of 310and 428 nm respectively.The selection of jellyfish candidates in MAC0717 fol-lowed the same general procedure as outlined here butthe dedicated catalogue of magnitudes and redshifts forthis specific system introduced some differences that willbe described in Section 3. We must note that, exceptfor MACS0717, our study relies on spectroscopic redshiftsgathered from NED, which are not complete in any way. Wewill therefore obtain some indications, but will not be ableto obtain statistically meaningful results, so this search ismainly a basis for future studies.Jellyfish galaxies are mainly accounted for by hydrody-namical interactions (ram pressure stripping) with the hotintracluster gas, which causes various observable effects onthe galaxy gas, such as compression of the leading edge ofthe galaxy, trailing tails, or even unwinding of spiral arms(Bellhouse et al. 2021). On the other hand, gravitationaleffects (tidal effects, harrassment) affect both gas and starsand can lead to galaxy shapes that can be reminiscent ofthose of jellyfish galaxies. It is therefore important to spotjellyfish candidates that may be undergoing tidal effectsfrom a neighbour galaxy. For this, we examined all the im-ages of jellyfish candidates and searched for galaxies locatedwithin a distance of 50 kpc. Out of the 90 (in MACS0717)and 103 (in the other clusters) jellyfish galaxy candidatesthat we initially identified, 9 (in MACS0717) and 6 (inother clusters) showed actual evidence for gravitational in-teraction (tidal arms), so they were eliminated from oursample. Among the remaining ones, 5 jellyfish candidates(in MACS0717) and 18 (in the other clusters) had possible companions but without any signature of interaction withthe jellyfish candidate. We kept these galaxies but markthem in Tables 2 and 3 with an asterisk. Our final sam-ple therefore includes 81 jellyfish candidates in MACS0717,and 97 in the 22 other clusters.
In order to obtain magnitude measurements for our candi-date jellyfish galaxies, we proceeded as follows.For all CLASH clusters except for MACS0717, we re-trieved the corresponding catalogues from the CLASH web-site that contain up to 17 wavebands, between 225 nm and1.6 µ m. Some of these magnitudes are given in Table 3, tohelp characterise the galaxies. The CLASH magnitudes arecorrected for Galactic extinction, and can therefore be usedfor spectral energy distribution analyses straightforwardly(section 5.2.3).For galaxies from the DAFT/FADA survey that are notpart of CLASH, we computed the zero points ZP AB apply-ing the HST formula: − . ∗ log10(PHOTFLAM) − ∗ log10(PHOTPLAM) − . , where the PHOTFLAM and PHOTPLAM values werefound in the image headers. We then ran SExtractor (Bertin& Arnouts 1996) on individual images and retrieved theMAG_AUTO magnitudes. The values given in Table 1 arecorrected for Galactic extinction computed from the E(B-V) maps by Schlegel et al. (1998) multiplied by the R valuesgiven in Table 6 of Schlafly & Finkbeiner (2011).For MACS0717: the F606W and F814W magnitudesfor the entire mosaic of images of MACS0717 were takenfrom the data by Martinet et al. (2017) (we did not usethe CLASH catalogue available in the F606W and F814Wfilters for this cluster because it only covers the central re-gion). We also used an eight-band ground-based optical andinfrared catalogue for the whole zone covered by MACS0717and its filament with Subaru/SuprimeCam data in the B,V, R c , I c and z bands, CFHT/MegaCam data in the u ∗ band, and CFHT/WIRCAM data in the near-infrared Jand K s bands from Jauzac et al. (2012). More details canbe found in Ma et al. (2008, 2009).This eight magnitude catalog for MACS0717 as well asthe 17 CLASH magnitudes for all the other CLASH clusterswere used to fit the spectral energy distributions of the jel-lyfish galaxies, and analyse their main stellar populations,with LePhare (Ilbert et al. 2006), through the GAZPARfacility as reported in Sect. 5. We also analyzed the stellarpopulations of non-jellyfish galaxies in MACS0717, in orderto compare the properties of our jellyfish candidates withthose of “normal” galaxies. In order to calculate the projected distances of jellyfishgalaxy candidates in units linked to the cluster properties,we compute for each cluster its r value, correspondingto the radius at which the cluster density is 200 times themean density of the Universe. We did this in several ways.For the seven clusters studied by Martinet et al. (2016), we https://gazpar.lam.fr/homeArticle number, page 4 of 44. Durret et al.: Jellyfish galaxy candidates in medium redshift clusters Table 1.
Clusters studied, ordered by right ascension. Columns are: cluster name (where the subscript C indicates that thecluster comes from the CLASH survey, the other clusters belonging to the DAFT/FADA sample), coordinates, redshift, numberof galaxies examined (i.e. galaxies in the cluster redshift range and found in the
HST images that we analyzed) and number ofjellyfish candidates. A zero in the sixth column means that none of the galaxies for which a spectroscopic redshift in the clusterrange was available appeared to be a jellyfish candidate. For the clusters in which jellyfish candidates were found, we give in thelast three columns the values of r , σ v , and the velocity interval ∆ v in which jellyfish candidates were searched in units of σ v (see text). The last three columns are empty for [ MJM98 ] _034, for which we did not find the information Cluster RA (J2000.0) Dec (J2000.0) redshift Obs. Jelly r σ v ∆ v/σ v (deg) (deg) gal. cand. (kpc) (km/s)Cl 0016+1609 4.64098 16.43796 0.5410 103 8 1820 1034 ± . Abell 209 C ± . Cl J0152.7-1357 28.17083 -13.96250 0.8310 66 6 1670 1083 ± . Abell 383 C ± . MACS J0416.1-2403 C ± . MACS J0429.6-0253 C ± . MACS J0454.1-0300 73.54635 -3.01494 0.5500 92 5 2110 1205 ± . MACS J0717.5+3745 C ± . MACS J0744.9+3927 C C ± . LCDCS 0172 163.60083 -11.77167 0.6972 45 9 870 526 ± . MACS J1115.8+0129 C C ± . MACS J1206.2-0847 C ± . BMW-HRI_J122657.3+333253 C ± . MACS J1311.0-0310 C [ MJM98 ] _034 203.80742 37.81564 0.3830 8 1LCDCS 0829 C ± . LCDCS 0853 208.54083 -12.51708 0.7627 20 7 1590 987 ± .
3C 295 CLUSTER 212.85167 52.21056 0.4600 30 8 1790 984 ± . MACS J1423.8+2404 C C ± . RCS J1620.2+2929 245.05000 29.48333 0.8700 1 0MACS J1621.4+3810 245.35292 38.16889 0.4650 1 0MS 1621.5+2640 245.89792 26.57028 0.4260 31 3 1718 941 ± . OC02 J1701+6412 255.34583 64.23583 0.4530 1 0RX J1716.4+6708 259.20667 67.14167 0.8130 22 1 1685 1085 ± . MACS J1720.2+3536 C C ± . MS 2053.7-0449 314.09083 -4.63083 0.5830 32 1 1620 952 ± . MACS J2129.4-0741 C C C ± . RX J2328.8+1453 352.20792 14.88667 0.4970 3 0directly take r from this paper. For the other clusters,we compute r from the M mass. Nine clusters have M values in Umetsu et al. (2018), and for the remain-ing clusters (except one, MJM98, for which we can not finda mass in the literature), we take the M masses derivedfrom X-ray masses by Chu et al. (A&A submitted). We thencalculate r by applying the following formula (Biviano,private communication): G × M = 100 × H ( z ) × r where H ( z ) = H × [Ω m (1 + z ) + Ω Λ ] (1 / is the Hubble parameter at the cluster redshift, z, com-puted with the cosmological parameters given at the end ofSection 1, and G is the gravitational constant.We also compute the cluster velocity dispersions usingequation (1) from Munari et al. (2013): σ v = 1090 × [ h ( z ) × M ] (1 / Article number, page 5 of 44 &A proofs: manuscript no. aanda where h ( z ) = H ( z ) / , M is expressed in units of M (cid:12) , and σ v is the unidimensional velocity dispersionin units of km/s.The values of r and σ v are given in Table 1 for allclusters that have jellyfish candidates.For each galaxy, we compute its velocity relative to themean cluster velocity in units of σ v , and give the corre-sponding values in Tables 2 and 3.
3. Jellyfish candidates in MACS J0717.5+3745(z=0.5458)
MACS0717 is a well-known massive cluster with a large ex-tension/filament reaching a total of about 9 Mpc towardsthe south-east and studied by Jauzac et al. (2012, 2018a,b)and Martinet et al. (2016). Based on a weak lensing study,its mass was estimated to be . × M (cid:12) within the R radius by Martinet et al. (2016). An extensive spectroscopicredshift catalogue, with 646 galaxies in the redshift inter-val . ≤ z ≤ . , allows us to search for jellyfishgalaxies in a very efficient way throughout the structure,which has been almost entirely covered by HST/ACS ob-servations.
Fig. 1.
In red, redshift histogram of the 646 galaxies in all theMACS0717 region, and in green, redshift histogram of the 81candidate jellyfish galaxies.
For this cluster, we examined 18 individual
HST/ACS images in both F606W and F814W bands. Out of the 646galaxies with redshifts in the cluster range, 81 were iden-tified as jellyfish candidates. The list of these galaxies isgiven in Table 2, and corresponding images are displayedin Appendix A. The histograms of all redshifts available inthe MACS0717 region and of the identified jellyfish galaxycandidates is shown in Fig. 1. This plot seems to show thatjellyfish candidates generally follow the velocity distribu-tion of the cluster.The jellyfish classification was separately made by twoof us, and the corresponding classes are given in the lasttwo columns (classS and classF) of Table 2. It appears thatclassF is often stricter than classS, so for some results shownbelow we made two samples of “strong probability” jellyfish objects (i.e. of types 3, 4 and 5), according to classF andto classS separately.
Fig. 2.
Colour-magnitude diagram for MACS0717. The bluepoints show the 81 candidate jellyfish galaxies belonging to thecluster. The full red line shows the position of the red sequenceand the dashed lines correspond to ± . on either side of thered sequence. The colour-magnitude diagram for MACS0717 is shownin Fig. 2. The red sequence drawn from Subaru data in theV and I bands was: V-I= − . × I+2.75 (Durret et al.2016), computed by considering the positions on this se-quence of several tens of galaxies at the cluster redshift. Itswidth of ± . was chosen to include all the galaxies belong-ing to the cluster according to their spectroscopic redshift,as explained by Durret et al. (2016). We adapted this redsequence to the F606W and F814W filters using the trans-formations given by Fukugita et al. (1995) and the result isshown in Fig. 2 (red lines). The data points refer to the jel-lyfish candidates found in the cluster. We can see that mostof them are blue and lie below the red sequence. For thefour galaxies located notably above the red sequence, the fitof the SED by a stellar population model (see Sect. 5.2.1)gives internal extinctions of 0.4 for three galaxies, and 0 forthe fourth one. Thus, except for the last galaxy, their redcolours may be at least partly explained by internal dust. The positions of the jellyfish candidates in MACS0717 areshown in Fig. 3. We highlight galaxies of types 3, 4 and5 (considering both classifications), since they have a highprobability of being real jellyfish galaxies. We can see thata large number is located outside the densest regions andabout one third lie in regions less dense than the σ contourabove the average background density. Interestingly, abouthalf of the jellyfish candidates are located in the extendedfilament South region of the cluster (filament C in Durretet al. (2016), the vertical yellow ellipse in Fig. 3), a low-density zone where only faint X-ray emission is detected(Ma et al. 2009), and therefore where RPS is not expectedto be strong but might be gently acting.Another way to illustrate the spatial distribution of jel-lyfish galaxies in the large scale MACS0717 structure is to Article number, page 6 of 44. Durret et al.: Jellyfish galaxy candidates in medium redshift clusters
Fig. 3.
Grey shading and green isocontours show the density map of red sequence galaxies taken from Durret et al. (2016). Theblack circle is centred on the cluster centre, and has a 1 Mpc radius. The two yellow ellipses show the 3 σ contours of the densitydistribution. The positions of the candidate jellyfish galaxies are indicated as follows: red circles: galaxies classified as jellyfish types3, 4, and 5 according to the strictest classification; blue: additional galaxies classified as types 3, 4, and 5 according to the lessstrict classification; black: all candidate jellyfish galaxies from Table 2. The yellow rectangle shows the approximate HST coverage. draw the histogram of projected distances to the clustercentre, as shown in Fig. 4. This figure confirms the paucityof jellyfish galaxies in the innermost cluster regions. Thehistogram of the galaxy velocities in units of σ v has a sim-ilar shape. This lack of jellyfish candidates in the clustercentre agrees with the model by Safarzadeh & Loeb (2019)that predicts no jellyfish galaxies at small clustercentric dis-tances. This result is at odds with the results of the GASPsurvey, where jellyfish galaxies at low redshift tend to befound in the innermost regions of clusters (Gullieuszik et al.2020).A morphometric analysis of the jellyfish galaxies inMACS0717, comparable to that performed by Roman-Oliveira et al. (2021) with MORFOMETRYKA on alarge sample of ram-pressure stripping candidates in theAbell 901/902 multi-cluster system, would be very inter-esting.
4. Jellyfish candidates in 22 other clusters
Positions and magnitudes of the 97 jellyfish candidatesfound in 22 clusters are given in Table 3. For CLASH clus-ters, galaxy coordinates are those of the CLASH catalogue,which always match very well those measured in the images. For the DAFT/FADA clusters, galaxy coordinates arethose measured by SExtractor on the HST images, as theyare more accurate than some of the coordinates extractedfrom NED. We checked by superimposing galaxies from theSDSS catalogue that the astrometry of our
HST images wascorrect.The redshift histogram of the 97 jellyfish candidatesfound in 22 clusters (other than MACS0717) is shown inFig. 5.
The images of the 97 jellyfish candidates are shown in Ap-pendix B. In some cases, we give below a few indications onspecific galaxies when we think it is useful and we indicateif clusters are merging whenever this information is avail-able. In particular, we mention if the positions of the jelly-fish candidates lie in the direction of the general elongationof the cluster, defined both from the position angle of thebrightest cluster galaxy, from the alignment of the brightestcluster galaxies, and from the red-sequence galaxy densitymaps drawn by Durret et al. (2016) and Durret et al. (2019)when available. This direction should trace the orientationof the filamentary regions, at large scale, where each clus-ter is embedded, and along which one would expect thelargest galaxy infall to happen (e.g. West 1994; West et al.
Article number, page 7 of 44 &A proofs: manuscript no. aanda
Fig. 4.
Red: histogram of the projected distance to the cluster centre of candidate jellyfish galaxies in MACS0717 (81 galaxies).Left: superimposed in blue: candidate jellyfish galaxies of classes 3, 4, and 5 according to the strictest classification (26 galaxies).Right: superimposed in green: candidate jellyfish galaxies of classes 3, 4, and 5 according to the less strict classification (47 galaxies).Distances are in in units of r . Fig. 5.
Redshift histogram of the 97 candidate jellyfish galaxiesin 22 clusters (excluding MACS0717).
Images of the eight jellyfish galaxy candidates in Cl0016+16are shown in Fig. B.1.1. Out of the eight jellyfish galaxies(out of 103 galaxies at the cluster redshift), four are wellaligned with the general cluster elongation (see Durret et al.(2019), Fig. B.1), and three others are not far from thisregion/direction.
Images of the two jellyfish galaxy candidates (out of 39galaxies at the cluster redshift) are shown in Fig. B.2. Oneof them is aligned along the cluster main elongation region((Durret et al. 2019), fig. B.2).
Images of the six jellyfish galaxy candidates (out of 66galaxies at the cluster redshift) are shown in Fig. B.3. All ofthem are in the Northern part of this merging cluster (seeGuennou et al. (2014) and references therein), which is themain zone covered by the HST image. Based on X-ray dataand on a large number of galaxy spectroscopic redshifts,Girardi et al. (2005) showed that Cl0152.7-1357 consistsof three galaxy clumps of different mean velocities: a lowvelocity clump in the central-South-West region, a high ve-locity clump in the Eastern region, and a weaker Easternclump.
Images of the two jellyfish galaxy candidates (out of 32galaxies at the cluster redshift) are shown in Fig. B.4. One islocated in the cluster elongation area (Durret et al. (2019),Fig. B.5), one is close to this region, and the third one isfurther out.
Images of the eight jellyfish galaxy candidates (out of 205galaxies at the cluster redshift) are shown in Fig. B.5.Galaxy f may be superimposed on a gravitational arc. Outof the eight jellyfish galaxies, seven seem to be roughly spa-tially aligned with the main cluster merging axis.
Article number, page 8 of 44. Durret et al.: Jellyfish galaxy candidates in medium redshift clusters
Images of the two jellyfish galaxy candidates (out of onlytwo galaxies at the cluster redshift) are shown in Fig. B.6,none of them being located along the main cluster elonga-tion area.
Images of the five jellyfish galaxy candidates (out of 92galaxies at the cluster redshift) are shown in Fig. B.7.Galaxy a may not be a jellyfish galaxy, but we keep it inthe sample because of its two nuclei. Two galaxies followthe main cluster elongation, and a third one is close-by.
Images of the eleven jellyfish galaxy candidates (out of 102galaxies at the cluster redshift) are shown in Fig. B.8. Allbut one are located in the Northern half of the cluster, butwith no specific alignment. This is a merging cluster (Durretet al. 2016).
The images of the nine candidate jellyfish galaxies (out of45 galaxies at the cluster redshift) are displayed in Fig. B.9,and show no particular spatial distribution.
Images of the four jellyfish galaxy candidates (out of 106galaxies at the cluster redshift) are shown in Fig. B.10.Three of them follow the main cluster elongation. Galaxiesc and d are interacting, with many filaments in their neigh-bourhood. Thus the image also shows their environment.
Images of the three jellyfish galaxy candidates (out of 64galaxies at the cluster redshift) are shown in Fig. B.11.Two of these galaxies are located along the main clusterelongation.
Images of the seven jellyfish galaxy candidates (out of 80galaxies at the cluster redshift) are shown in Fig. B.12.Their spatial distribution shows no particular trend. Thebright arc North and East of galaxy e is a gravitationalarc.
Image of the single jellyfish galaxy candidate (out of eightgalaxies at the cluster redshift) is shown in Fig. B.13. Asnoted by Guennou et al. (2014) this cluster is at redshiftz=0.383 and not at z=0.5950 as found in NED.
Image of the single jellyfish galaxy candidate (out of 35galaxies at the cluster redshift) is shown in Fig. B.14. Itsposition is roughly aligned with the cluster elongation.
Images of the seven jellyfish galaxy candidates (out of 20galaxies at the cluster redshift) are shown in Fig. B.15. Allseven galaxies are located in the South-East quarter of thecluster.
Images of the eight jellyfish galaxy candidates (out of 30galaxies at the cluster redshift) are shown in Fig. B.16.They show no particular distribution throughout the clus-ter. Due to different spatial coverage, some appear in bothfilters, others only in one.
Image of the single jellyfish galaxy candidate (this galaxyis in fact the brightest cluster galaxy, and there is onlyone other galaxy with a measured redshift in the cluster) isshown in Fig. B.17, as well as a zoomed image showing adisturbed structure.
Images of the three jellyfish galaxy candidates (out of 31galaxies at the cluster redshift) are shown in Fig. B.18.They show no particular distribution in the cluster. Thetwo filters do not cover exactly the same region. Galaxy amay be interacting with one or two galaxies, but spectro-scopic redshifts are not available for these objects. Galaxy bhas a plume of emission to the South, and seems to be sur-rounded by gravitational arcs in the North. Spectroscopy isalso needed to confirm the jet-like feature East of galaxy c.
Image of the single jellyfish galaxy candidate (out of 22galaxies at the cluster redshift) is shown in Fig. B.19.
Images of the two jellyfish galaxy candidates (out of onlythree galaxies at the cluster redshift) are shown in Fig. B.20.
Image of the single jellyfish galaxy candidate (out of 32galaxies at the cluster redshift) is shown in Fig. B.21. Itlies exactly North of the cluster centre, positioned alongthe direction of the cluster elongation.
Images of the five jellyfish galaxy candidates (out of 42galaxies at the cluster redshift) are shown in Fig. B.22. Two
Article number, page 9 of 44 &A proofs: manuscript no. aanda out of five galaxies are located within the cluster elongationarea/direction.
5. Jellyfish galaxy candidate properties
The histogram of the projected distances of jellyfish galaxycandidates to the centre of the respective cluster is shownin Fig. 6, where we compare the result already shown forMAC0717 but limited to within 1800 kpc (on the left) withthe results obtained for all the other clusters taken together(right panel). This figure shows that the number of jelly-fish galaxy candidates in the central region of MACS0717is rather small, whereas it is large in the ensemble of allthe other clusters. Unlike for MACS0717, our coverage ofthe remaining clusters is far from complete; nonetheless,this result indicates that in MACS0717 there seems to be areal absence of jellyfish galaxy candidates in the innermostcluster region.
We matched our catalogue of 81 jellyfish galaxy candidatesdetected in MACS0717 with the eight band optical andinfrared ground-based catalogue covering the entire regionof MACS0717 described in Section 2. We found 79 galaxiesin common using a match radius of 1.5 arcsec.We then used LePhare (Ilbert et al. 2006), through theGAZPAR interface , to fit the spectral energy distribu-tions (SED) of these 79 jellyfish galaxy candidates with theBruzual & Charlot (2003) models and the Chabrier (2003)initial mass function: based on an input catalogue with po-sitions, magnitudes and corresponding errors, and in ourcase spectroscopic redshift, LePhare fits the galaxy SED,computes absolute magnitudes in the input bands, and in-fers, from the best fit template in each case, the stellar mass,star formation rate, specific star formation rate, mean stel-lar population age, as well as other quantities that we willnot consider here. The input parameter space was carefullyselected so as to cover the expected characteristics of late-type galaxies with probable SF activity.We can note that for all 79 galaxies but a few the best fittemplate spectrum includes an H α line, and among theseabout 80% of the template spectra include all the mainemission lines in the optical ([OII]3727, [OIII]4959, 5007,H β and H α ), thus implying that the majority of our jel-lyfish candidates are forming stars. As an illustration ofthe obtained fits, we show in Fig. 7 the SED and best fittemplates for two galaxies, one with only a weak H α emis-sion line and one with several emission lines in the bestfit template. We see that these fits are quite good, and thiswas indeed the case for all galaxies that GAZPAR/LePhareanalysed.The histogram of jellyfish galaxy candidate stellarmasses in MACS0717 is shown in the left-hand panel ofFig. 8. The galaxies cover the range of stellar masses be-tween and M (cid:12) . We divided the sample into high-mass (log M ≥ ) and low-mass (log M < ) galaxies and https://gazpar.lam.fr/home checked their spatial distribution but found no differencebetween these two samples.The histogram of jellyfish galaxy candidate star forma-tion rates for MACS0717 is shown in the left hand panel ofFig. 9. The SFRs cover a large range, essentially between0.1 and 60 M (cid:12) yr − . We also show in Fig. 10 the histogramof the specific star formation rates in MACS0717: values gofrom − to − yr − (except for two galaxies that havevery low sSFRs and do not appear on the figure), and morethan 30 galaxies have sSFR > − yr − . We mark on thesSFR histograms the indicative value of log(sSFR) = − below which galaxies are commonly considered to be quies-cent.The histogram of the stellar population age for the jel-lyfish galaxy candidates in MACS0717 is shown in Fig. 11.We can see that more than half of the galaxies are, on av-erage, younger than . × yrs, so the stellar populationis globally quite young.The relation between the SFR and galaxy stellar massesis shown in Fig. 12. We superimposed on this plot the mainsequence of SF galaxies as determined by Peng et al. (2010),based on a very large sample of galaxies from the SDSS andzCOSMOS surveys, and its dispersion that we estimated tobe ± . around the relation (see their Fig. 1). We see that12 (15%) jellyfish galaxies are below this sequence, 23 (29%)are in the interval of Peng et al. (2010), and the 44 otherones (56%) lie above the SF main sequence.In agreement with the previously noted fact that SEDsof the jellyfish galaxies in MACS0717 are in majority bestfitted by a spectrum including one or several emission lines,this confirms that, in average, jellyfish galaxy candidatesseem to have a higher SFR than “normal” star forminggalaxies of the same stellar mass. Figure 12 suggests thatthe majority seems to form a sequence parallel to that ofPeng et al. (2010), but with a SFR about 10 times higher.There are, however, a few cases of very low specific starformation rates: these galaxies are apparently quenched, asindicated by the log(sSFR) < − criterion (see Fig. 10).As a comparison, we also obtain an SED fit for 442galaxies in the same redshift interval but not classifiedas jellyfish candidates. Out of these, 113 galaxies can beconsidered as non-quiescent (specific star formation ratelog(sSFR) ≥ − ). We also include these galaxies in Fig. 12.One can see that they cover more or less the same regionas the jellyfish candidates. However, if we calculate the av-erage sSFR for the jellyfish candidates and for this controlsample, both limited to logsSFR ≥ − (respectively: 71and 113 galaxies), we find respective values of − . and − . , suggesting that the sSFR is about 3 times larger forjellyfish candidates. In view of the errors on these quanti-ties, this value of 3 should not be taken at face value, butit does suggest that jellyfish galaxies have a sSFR higherthan that of “normal” galaxies.We also overplot on Fig. 12 (left panel) the relationsfound by Vulcani et al. (2018) for disks of ram pressurestripped galaxies (in blue), and undisturbed galaxies (inblack). One can note that at least half of our jellyfish can-didates are located above both their sequences.As a final check, and since jellyfish galaxies are veryoften systems with an increased star formation rate (seethe Introduction), we verified if our results were affectedby classification errors in the following manner. We dividedour sample in two sub-samples based on the classF columnof Table 2: types 1 and 2 on one side, types 3, 4 and 5 on the Article number, page 10 of 44. Durret et al.: Jellyfish galaxy candidates in medium redshift clusters
Fig. 6.
Left: histogram of the projected distance of 61 jellyfish galaxy candidates to the cluster centre for MACS0717, in unitsof r , with the same limit as the figure on the right. Right: same histogram for the 97 jellyfish galaxy candidates of the otherclusters. Fig. 7.
For two of the jellyfish galaxy candidates in MACS0717, in black: 8 magnitudes available from the Jauzac et al. (2012)catalogue, in red: best stellar population fit superimposed, one with a weak H α emission line (left) and one with several strongemission lines (right). other. We then checked the numbers of each type in Fig. 12(left), to see if the galaxies with a SFR lower than the mainsequence were in majority of types 1 or 2 (i.e. galaxies thatmay not be jellyfish galaxies after all). The percentages ofjellyfish galaxy candidates of types 1 and 2 with a SFRbelow, in, and above the Peng sequence are comparable tothose given above for all the jellyfish galaxy candidates.We therefore consider that galaxies with a low SFR are notnecessarily doubtful jellyfish galaxies. This means that anumber of our jellyfish candidates are indeed undergoing aphase of low star formation activity. An interesting link between the presence of jellyfish featuresand AGN activity was explored by Poggianti et al. (2017a),who found a strong correlation between these parametersfor the most extreme examples of jellyfish galaxies in theirGASP sample. Motivated by this, we checked if any of ourjellyfish candidates in MACS0717 showed signs of hosting an AGN. This is a hard task with the limited data availableso, considering the possibilities, we opted for using the MIRcriteria, based on WISE colors, developed by Mateos et al.(2012) and Stern et al. (2012). Both are optimized to selectluminous AGN so we will likely just uncover the tip of theiceberg.We used the Table Access Protocol (TAP) Query ser-vice of TOPCAT (Taylor 2005) to access and download theDR8 tractor catalogue limited to the area covered by theHST observations. This catalogue contains magnitudes inall four WISE bands, extracted by the DESI team in prepa-ration for their Legacy Survey, that go about 1 magnitudedeeper than the original AllWISE ones (D. Schlegel, pri-vate communication). We converted these de-redenned ABmagnitudes to the Vega system, following the DESI web-page information , to apply directly the above mentionedcriteria. We then matched this catalogue with our own: fora search radius of 1.5 arcsec, 79 of our 81 galaxies had datain the DR8 tractor catalogue, allowing us to check their &A proofs: manuscript no. aanda Fig. 8.
Histograms of the stellar masses for the 79 jellyfish galaxy candidates in MACS0717 (left), and 31 galaxies of other clusters(right).
Fig. 9.
Histograms of the star formation rates for the 79 jellyfish galaxy candidates in MACS0717 (left), and 31 galaxies of otherclusters (right).
W1-W2 color index. Out of these, only two barely pass theStern et al. (2012) threshold for identifying AGN, i.e. acolor index W1-W2>0.8, imposing as well a S/N>5 for theWISE individual magnitudes. These are galaxies σ v ∼ − , W1-W2=0.90 and J class 4 attributed by both FD and SC:it is galaxy σ v ∼ − . and W1-W2=0.84.The respective stellar masses of galaxies . × and . × M (cid:12) , and their respective SFRs are 6.9and 14.7 M (cid:12) yr − . However, if these galaxies indeed hostan AGN, then the LePhare output parameters can only betaken as indicative since they are likely affected by larger uncertainties (the SED fits did not take into account anyAGN contribution). In our cluster sample, there are 11 CLASH clusters listed inTable 4, in which we find a total of 31 jellyfish galaxy candi-dates. These galaxies have optical and infrared magnitudesavailable (up to 17 bands between 225 nm and 1.6 µ m, fromthe CLASH program, see section 2).We fit SEDs of these 31 galaxies in the same way asthose in MACS0717 with GAZPAR/LePhare. The best fittemplate spectrum includes an H α line for all but two galax-ies and, except for these two, more than half of the best fittemplate spectra include all main emission lines in the op-tical ([OII]3727, [OIII]4959, 5007, H β and H α ), here alsosuggesting that the majority of these jellyfish galaxy can-didates are forming stars.Similar plots to those shown for MACS0717 are givenin the right panels of Figs. 8 to 12. We can see that stellarmasses of these 31 galaxies cover a range comparable to thatcovered by the jellyfish galaxy candidates in MACS0717. Article number, page 12 of 44. Durret et al.: Jellyfish galaxy candidates in medium redshift clusters
Fig. 10.
Histograms of the specific star formation rates of the 79 jellyfish galaxy candidates in MACS0717 (left), and 31 galaxiesin the other clusters (right). The black vertical dashed line shows the value of -11 below which galaxies are considered as quiescent.
Fig. 11.
Histograms of the stellar population ages of the 79 jellyfish galaxy candidates in MACS0717 (left), and 31 galaxies in theother clusters (right).
Their SFRs are also comparable to those in MACS0717,but we can note that only two galaxies out of 31 (6%)have SFR > M (cid:12) yr − (though one is possibly overesti-mated), whereas there are 25 (32%) in MACS0717. Fig. 12also shows that while MACS0717 seems to be quite richin jellyfish galaxy candidates having a high SFR, for theother clusters a clear assessment for comparison is diffi-cult due to their incomplete coverage. The distribution ofthe specific star formation rate is quite different in the twosamples (Fig. 10): 35 (44%) of the galaxies in MACS0717have sSFR ≥ − yr − while the distribution of sSFRs forthe 31 other jellyfish galaxy candidates is “smoother", with12 (39%) galaxies having sSFR ≥ − yr − , though veryfew are quiescent (sSFR < − yr − ). Consistently, thedistributions of the mean ages of the stellar populations ofthe two samples are also quite different, as seen in Fig. 11:half of the galaxies in MACS0717 are on average youngerthan . × yrs, while the age distribution in the sampleof 31 galaxies is flatter.Again, we underline that these comparisons are merelyindicative, since the sample of 31 jellyfish galaxy candidates results from a spectroscopic and spatial coverage that isquite incomplete, and therefore by no means identical tothat of MACS0717.We also looked for variations of the stellar mass, SFRand sSFR with redshift for these 31 galaxies, but the dis-persion is large, specially for the first two quantities, so wecannot claim there are clear correlations.Finally, we checked if there was a correlation betweenthe jellyfish classification and the stellar mass, both in the79 galaxies of MACS0717 and in the 31 galaxies belongingto other clusters, and indeed found none, in agreement withthe results of Poggianti et al. (2016). There are 17 clusters in our sample in which no jellyfishgalaxy candidate was detected (see Table 1). For 13 ofthem, there are only between one and three galaxies witha spectroscopic redshift available at the cluster redshift,and located in the zone covered by
HST images. For theremaining four clusters, BMW-HRI_J122657.3+333253,
Article number, page 13 of 44 &A proofs: manuscript no. aanda
Fig. 12.
SFR as a function of stellar mass for the 79 jellyfish galaxy candidates in MACS0717 (left) and 31 galaxies of other clusters(right). On both figures, the three green lines indicate the relation found by Peng et al. (2010) and its approximate dispersion of ± . (dashed lines). On the left figure, pink dots correspond to “normal” cluster galaxies with log(sSFR) ≥ − (see text). Blueand black lines show the relations found by Vulcani et al. (2018) for the disk SFR–mass relation for stripping and control samplegalaxies respectively (see their Fig. 1). On the right panel, the two red points highlight the two galaxies with log(sSFR) < − ZwCl 1332.8+5043, MACS J1423+24, and Abell 2261,there are respectively 23, 6, 7, and 14 galaxies with a spec-troscopic redshift available at the cluster redshift, and lo-cated in the zone covered by
HST . So obviously, at least inthe last three of these four clusters, the absence of jellyfishgalaxies in these clusters can simply be due to the smallnumber of available redshifts.
6. Discussion and conclusions
We searched for jellyfish galaxy candidates in an initial sam-ple of 40 clusters in the redshift range . < z < . fromthe DAFT/FADA and CLASH surveys with HST opticalimages available. To this purpose, two of us examined theshapes of all galaxies with a spectroscopic redshift in theapproximate cluster range. This approach led us to find oneor several jellyfish galaxy candidates in 23 clusters (from theoriginal set of 40), that were classified from J=1 to J=5, fol-lowing the classification scheme proposed by Ebeling et al.(2014). In the remaining 17 clusters we found no jellyfishcandidate. We analysed cluster MACS0717 separately, be-cause it has a large HST coverage and spectroscopic cata-logue: in this system, we found 81 jellyfish candidates. Inthe remaining 22 clusters, we detect a total of 97 jellyfishgalaxy candidates.For all these jellyfish candidates, we give positions, red-shifts, magnitudes in one or two optical filters (usuallyF606W and F814W), and show images in the Appendix.Whenever images are available for the galaxies in these twowavebands, we provide both: the comparison of galaxy im-ages in the F606W and F814W filters shows that our can-didates are morphologically quite similar in both, but withmore evidence for star formation in the bluer filter. as ex-pected.A colour-magnitude diagram for MACS0717 shows thatmost of the 81 jellyfish candidates are blue and located be-low the cluster red sequence. This is reinforced by the UVJdiagram (Williams et al. 2009), where only two galaxiesappear to be quenched; all remaining ones seem to be SF galaxies, even if several of them lie in the region of dustobscured objects (thus can be red sequence objects). Forthe 79 jellyfish candidates in this cluster having multiwave-length data available, the SED fitting that was carried outwith LePhare finds that almost all are best fit by templatespectra that have one or several of the main optical emis-sion lines usually associated with ongoing star formation.As a consequence, the stellar mass – SFR plane (where thesequantities were also obtained by LePhare directly from thebest fit template spectra), shows that at least 80% of thejellyfish candidates are star-forming galaxies - and amongthese SF systems, about 70% have increased SFR relativelyto the main sequence galaxies. The SED fit results thus pro-vide another indication that the majority of jellyfish galax-ies in this cluster have notably high SFR for their stellarmasses (about 60% have sSFR > − yr − , stellar massesranging from . to . M (cid:12) ). Though affected by theusual uncertainties associated with any SED fitting method,this result is similar to what was obtained at low redshiftby Poggianti et al. (2016).If we now look at the location of these galaxies insidethe cluster, their redshift histogram does not hint for anyparticular placement along the line-of-sight: jellyfish candi-dates share the global redshift distribution of all galaxieswithin the structure (i.e. all galaxies within the adoptedredshift interval for this system), so it is impossible to in-fer any particular kinematical behavior. As for their spatialdistribution on the plane of the sky, jellyfish candidatesspread throughout the cluster and its extended filament butavoid the cluster central, densest region. Since MACS0717filaments are well detected in projection, and the redshifthistogram of the whole structure (Fig. 1) is, rather surpris-ingly, Gaussian-like, it does look as if the main infall, atlarge scale, should essentially take place along the plane ofthe sky, in the areas where we found our jellyfish candidates.In the cluster core, and apparently in compliance withthe model of Safarzadeh & Loeb (2019), jellyfish galaxy can-didates are almost absent, which may further be a result ofthe very rough core environment of this massive merging Article number, page 14 of 44. Durret et al.: Jellyfish galaxy candidates in medium redshift clusters cluster. A detailed study of the inner 1 Mpc carried outwith combined optical and X-ray data by Ma et al. (2009)does point to much more complex dynamics in the clus-ter core (when compared with what we can infer from theglobal redshift histogram of Fig. 1). Interestingly enough,Ellien et al. (2019) analyzed the distribution of intra-clusterlight (ICL) in this system and detected a large amount of itin the cluster core but no such light in the cosmic filament.As ICL is thought to be made up of disrupted galactic ma-terial, the findings of Ellien et al. (2019) corroborate theexistence of a harsh environment in the core, contrastingwith softer conditions along the filament. This is expectedand the distribution of jellyfish galaxy candidates found inthis work may reflect that, quite probably, transient phe-nomena such as jellyfish features cannot survive for long inthe tumultuous core of MACS0717.From all these pieces of evidence, we think that mostjellyfish candidates identified here could be a population ofrather recent infallers that have felt the first impact andeffects of penetrating into a denser environment, which al-tered their morphology and generally increased their SFR.A tentative MIR analysis singles out two possible AGNhosts among the jellyfish candidates located in the densercluster regions.On the other hand, the apparent paucity of jellyfishgalaxies in the cluster core could simply be the result of aselection effect, imposed by the wavelengths that we relyupon to identify them - probing, approximately, restframeB and V optical emission. Though these wavebands havebeen successfully used by Poggianti et al. (2016) to selecttheir GASP jellyfish candidates at redshifts 0.04-0.07, weexpect that at the higher redshifts of our sample, the sur-face brightness of jellyfish structures becomes significantlydimmer. Moreover, tails and other jellyfish characteristicscan indeed lie undetected in some filters since the materialmaking up the jellyfish structures emits at selective wave-lengths, as documented by several examples mentionedin Section 1. Just to highlight a couple of illustrativeexamples, and regardless of their location within the hostcluster, we can mention FGC1287 in Abell 1367 thathas a 250 kpc-long HI tail with no optical counterpart(Scott et al. 2012), and D100 in Coma, which presents aremarkably long and narrow ( × . kpc) H α gas tail,whereas the optical image shows an apparently normalspiral galaxy (Cramer et al. 2019). Such galaxies with tailsare rather extreme examples of jellyfish characteristicsbut they seem to be located - at least in what concernsthe low-redshift universe, i.e. mostly below z=0.05 butreaching up to z=0.2 - within the inner 40% of their clustervirial radius (i.e. within 1 Mpc) with very few exceptions(T. Scott, private communication). This is the case evenfor those with stellar tails - that could thus potentiallybe unveiled in our observations. So, as far as opticallydetected jellyfish galaxy candidates are concerned, theredon’t seem to be many in the inner regions of MACS0717,at least as far as our images’ depth can probe, and noneshows a conspicuous tail.Unlike the large spectroscopic coverage we have forMACS0717, that allowed us to detect in a more completeway jellyfish candidates in this cluster, the lack of redshiftsin the case of most of the other clusters that we anal-ysed prevents us from drawing major conclusions. Our aimhere was simply to detect candidates, characterize them and make, whenever possible, a comparison with what wasfound for MAC0717. The jellyfish candidates detected inall remaining 22 clusters cover the same stellar masse rangebut don’t seem to avoid the centre of their host clusters, asseen in Fig. 6. This might explain the generally lower SFRvalues (only reaching about M (cid:12) yr − ) when comparedwith jellyfish candidates that are members of MACS0717.Finally, and considering the whole sample together, wenext attempt to infer proportions of jellyfish galaxy candi-dates in the clusters analysed here and the existence of anytrend with cluster relaxation states.We already mentioned the incompleteness of our red-shift catalogues for the various clusters. As jellyfish galaxiesare most often quite bright, and/or show emission lines intheir spectra, they may be easier to observe spectroscopi-cally, and thus their proportion may be overestimated. Be-sides, since our aim is to detect jellyfish galaxies, we mayhave classified as such, galaxies which are merely some-what strange–looking spirals with a distorted morphology.For these reasons, and due to the incompleteness of oursample, estimating the proportion of jellyfish galaxies inclusters remains difficult. We will therefore just give a fewnumbers. If we consider the 21 clusters for which more thanten spectroscopic redshifts are available, we find an averageproportion of jellyfish galaxy candidates of 9.5% (by usingthe numbers in Table 1). If we now consider MACS0717,where statistics are more robust (81 jellyfish candidates de-tected, with a large spectroscopic and spatial coverage), wefind a percentage of 13%. This seems to mean that jelly-fish galaxies are not that rare after all, and it is a clearencouragement to pursue such studies with more completespectroscopic data.Since the main mechanisms leading to jellyfish galax-ies appear to be RPS and/or harassment Poggianti et al.(see the Introduction and 2017b), the proportion of jellyfishgalaxies can be expected to vary with the relaxation stateof clusters to which they belong. To estimate this relaxationstate, we looked at several properties: first, the histogramsof all the redshifts available in a large zone around each clus-ter (for the DAFT/FADA clusters, these histograms weregiven by Guennou et al. (2014) and Durret et al. (2016)),for the other clusters we retrieved all the redshifts avail-able in NED and drew their histogram in the approximatecluster redshift range. We also looked at the matter distri-bution based on a weak lensing analysis by Martinet et al.(2016) or on the shape of the red sequence density map byDurret et al. (2016) or Durret et al. (2019). For clusterswith at least 10 spectroscopic redshifts available within the HST images analyzed in the present paper, we looked atthe proportion of jellyfish galaxy candidates relative to therelaxation state of the cluster. With the available data, wefound no relation between the proportion of jellyfish galaxycandidates and the relaxation state of the cluster.
Acknowledgements.
It is a pleasure to thank Tom Scott for enlight-ening discussions about RPS and its effect on cluster galaxies. Weare grateful to the referee for her/his prompt report and interest-ing suggestions that helped to improve the paper. F. Durret ac-knowledges continuous financial support from CNES since 2002. C.Lobo acknowledges support by Fundaçao para a Ciência e a Tec-nologia (FCT) through the research grants UIDB/04434/2020 andUIDP/04434/2020. M. Jauzac is supported by the United KingdomResearch and Innovation (UKRI) Future Leaders Fellowship ‘Us-ing Cosmic Beasts to uncover the Nature of Dark Matter’ (grantnumber MR/S017216/1). This work is partly based on tools anddata products produced by GAZPAR operated by CeSAM-LAM andIAP and we further acknowledge the dedicated support of O. Il-
Article number, page 15 of 44 &A proofs: manuscript no. aanda bert. This research has made use of the SVO Filter Profile Service(http://svo2.cab.inta-csic.es/theory/fps/) supported from the Span-ish MINECO through grant AYA2017-84089. This research has alsomade use of the NASA/IPAC Extragalactic Database (NED), whichis funded by the National Aeronautics and Space Administration andoperated by the California Institute of Technology. We further ac-knowledge M. Taylor for developing TOPCAT, making our life somuch easier.
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Article number, page 16 of 44. Durret et al.: Jellyfish galaxy candidates in medium redshift clusters
Table 2.
Jellyfish candidates in the large structure enclosing the cluster MACS J0717.5+3745. Columns are: galaxy number, RA,DEC, redshift, F606W and F814W magnitudes, jellyfish classifications S and F by two of the authors (SC and FD), projecteddistance to cluster centre in kpc and in units of r , and velocity relative to cluster centre divided by cluster velocity dispersion.
Galaxy number RA DEC z F606W F814W S F Dist. Dist. v/ σ v (kpc) (r )1 109.28460 37.76579 0.5424 21.402 20.539 3 2 2453 1.097 − . − . ∗ − . − . − . ∗ − . − .
10 109.37781 37.71374 0.5374 21.923 20.766 3 3 1007 0.450 − .
11 109.37863 37.78915 0.5754 22.365 21.570 5 5 822 0.367 3.6512 109.38213 37.72594 0.5315 22.126 21.245 4 4 710 0.317 − . ∗ − .
14 109.39410 37.79197 0.5757 22.878 22.084 2 2 840 0.376 3.6815 109.39528 37.84684 0.5348 21.759 20.512 1 1 2101 0.940 − .
16 109.39620 37.76458 0.5490 22.027 21.231 3 2 241 0.108 0.4017 109.40541 37.70779 0.5290 22.269 21.554 1 1 1148 0.514 − .
18 109.40749 37.61744 0.5456 22.097 21.340 4 4 3199 1.431 − .
19 109.40773 37.62261 0.5459 21.055 20.251 2 2 3082 1.378 0.0120 ∗ − .
21 109.41522 37.72866 0.5395 22.709 21.719 3 2 835 0.373 − .
22 109.41720 37.70310 0.5420 22.270 21.353 4 4 1350 0.604 − .
23 109.41817 37.79837 0.5634 22.225 20.565 4 3 1168 0.522 2.1824 109.42203 37.74784 0.5660 22.493 21.425 3 2 768 0.343 2.5025 109.42928 37.67791 0.5442 20.739 19.954 3 2 1992 0.891 − .
26 109.42990 37.78072 0.5622 22.227 21.308 3 3 1068 0.478 2.0427 109.43111 37.62285 0.5472 21.150 20.410 2 2 3189 1.426 0.1828 109.43424 37.75050 0.5500 22.224 20.866 1 2 1005 0.449 0.5229 109.43758 37.72152 0.5409 22.502 21.217 2 0 1330 0.595 − .
30 109.43866 37.79811 0.5384 21.801 20.199 1 0 1472 0.658 − .
31 109.44090 37.77155 0.5521 22.692 21.920 3 1 1209 0.540 0.7932 109.44299 37.72516 0.5429 20.538 19.928 1 0 1388 0.621 − .
33 109.44773 37.63008 0.5469 22.637 21.694 3 2 3168 1.417 0.1434 109.44783 37.68979 0.5577 21.773 21.141 2 3 2001 0.895 1.4835 109.45184 37.61336 0.5475 22.227 21.117 2 1 3558 1.591 0.2136 109.45511 37.64426 0.5404 21.156 20.171 2 2 2955 1.322 − .
37 109.45564 37.62384 0.5480 21.919 21.650 2 2 3375 1.510 0.2838 109.45809 37.75248 0.5546 22.010 21.090 4 2 1548 0.692 1.1039 109.45857 37.61006 0.5511 21.694 20.937 5 4 3690 1.650 0.6640 109.46005 37.73063 0.5401 21.537 20.933 5 2 1692 0.757 − .
41 109.46016 37.58284 0.5439 21.075 20.242 4 1 4279 1.914 − . − .
45 109.47195 37.61126 0.54703 21.526 20.278 1 0 3806 1.702 0.1546 109.47451 37.70863 0.5311 21.922 20.994 3 2 2206 0.987 − .
47 109.47494 37.77757 0.5451 21.181 20.115 3 0 1999 0.894 − .
48 109.47574 37.71760 0.5440 22.315 19.658 4 2 2139 0.956 − .
49 109.48136 37.74231 0.5637 21.287 20.237 2 0 2104 0.941 2.2250 109.48801 37.72609 0.5362 22.385 21.872 4 5 2335 1.044 − .
51 109.48879 37.55154 0.5293 22.061 21.185 4 3 5204 2.327 − .
52 109.49406 37.56277 0.55338 22.452 21.247 2 0 5028 2.249 0.9553 109.49385 37.64037 0.5461 22.405 21.182 2 3 3553 1.589 0.0454 109.49413 37.59956 0.5464 22.503 20.107 5 2 4302 1.924 0.0755* 109.50267 37.65858 0.5772 22.103 21.021 4 3 3404 1.522 3.8656 109.50533 37.63641 0.5412 20.762 19.552 3 1 3800 1.699 − . Article number, page 17 of 44 &A proofs: manuscript no. aanda
Table 2.
Continued.
57 109.50554 37.61765 0.5426 22.114 21.392 3 3 4125 1.845 − .
58 109.50652 37.67290 0.5430 21.256 20.058 1 0 3269 1.462 − .
59 109.50808 37.64077 0.5420 21.681 20.739 3 2 3773 1.687 − .
60 109.50873 37.62831 0.5425 23.489 21.638 2 2 3989 1.784 − .
61 109.50883 37.63732 0.5481 21.519 20.357 2 2 3841 1.718 0.2962 109.52255 37.55546 0.5465 22.372 21.748 4 2 5508 2.463 0.0963 109.53121 37.63280 0.5421 22.468 21.475 4 4 4288 1.918 − .
64 109.53217 37.58715 0.5447 21.959 21.064 5 4 5055 2.261 − .
65 109.53279 37.55027 0.5495 21.663 20.238 1 0 5739 2.567 0.4666 ∗ − .
69 109.54137 37.70054 0.5419 21.532 20.190 1 0 3685 1.648 − .
70 109.55122 37.64091 0.5701 22.283 21.443 3 2 4533 2.027 3.0071 109.55586 37.57695 0.5500 21.673 20.747 3 1 5592 2.501 0.5272 ∗ − .
73 109.56507 37.57967 0.5488 21.814 20.612 4 2 5693 2.546 0.3874 109.57690 37.67111 0.5236 22.552 21.855 2 3 4698 2.101 − .
75 109.58230 37.62237 0.5625 21.298 20.379 4 0 5363 2.398 2.0776 109.58243 37.60096 0.5449 22.312 21.025 2 2 5661 2.532 − .
77 109.58437 37.68565 0.5482 21.371 20.508 2 0 4732 2.116 0.3078 109.58499 37.61001 0.5489 22.352 21.587 5 4 5579 2.495 0.3979 109.59241 37.65249 0.5378 24.508 21.100 4 3 5206 2.328 − .
80 109.60329 37.59384 0.5542 21.376 20.345 4 4 6139 2.746 1.0581 109.60480 37.64520 0.5225 22.826 22.159 3 2 5536 2.476 − . Article number, page 18 of 44. Durret et al.: Jellyfish galaxy candidates in medium redshift clusters
Table 3.
List of the 97 candidate jellyfish galaxies in 22 clusters. Columns are: cluster name, galaxy identification, galaxycoordinates, redshift, magnitudes in the bands where images used for classification are available, jellyfish classes F and S, projecteddistance to the cluster centre in kpc and in units of r , and ratio of the difference between the galaxy velocity and that of thecluster divided by the cluster velocity dispersion.
Cluster G. RA DEC z F555W F606W F702W F814W F S Dist. Dist. v/ σ v F775W (kpc) (r )Cl 0016+16 a 4.62890 16.42794 0.5561 19.824 4 4 361 0.198 2.35b 4.63388 16.42250 0.5498 20.742 3 3 391 0.215 1.37c 4.63674 16.43428 0.5382 21.770 2 1 129 0.071 − . d 4.64164 16.44986 0.56 22.033 5 5 274 0.151 2.95e ∗ − . h 4.66072 16.45040 0.5642 19.872 3 5 536 0.295 3.59Abell 209 a 22.95776 -13.60326 0.2123 19.967 19.283 2 2 176 0.073 1.25b ∗ ∗ − . e 28.17714 -13.93879 0.8215 21.321 2 1 672 0.402 − . f 28.17842 -13.96492 0.8371 23.681 2 1 218 0.131 0.65Abell 383 a 42.01002 -3.55678 0.1944 19.487 18.675 1 3 218 0.111 1.83b 42.03447 -3.52755 0.1914 19.017 18.311 2 2 315 0.161 1.08MACS J0416.1-2403 a ∗ ∗ − . c 64.02498 -24.09166 0.3944 21.533 20.844 0 1 582 0.241 − . d 64.02779 -24.06101 0.3918 22.618 21.893 1 2 277 0.114 − . e 64.03268 -24.07015 0.3973 21.410 20.506 2 2 182 0.075 0.19f 64.04131 -24.07134 0.3990 20.676 19.707 2 3 101 0.042 0.44g ∗ − . MACS J0429.6-0253 a 67.38860 -2.88379 0.4 20.798 20.505 4 4 223 0.129 0.21b 67.41844 -2.88832 0.4049 20.920 20.665 4 3 360 0.208 1.22MACS J0454.1-0300 a 73.51869 -3.00396 0.5323 19.910 5 5 679 0.322 − . b 73.53999 -3.01686 0.5483 20.118 1 2 152 0.072 − . c ∗ − . d ∗ − . e 73.56342 -2.99819 0.528 20.116 1 2 546 0.259 − . Abell 851 a 145.68898 46.98263 0.407 20.668 2 2 1033 0.670 0.02b 145.69411 47.00624 0.4083 20.092 2 1 1005 0.652 0.32c 145.71105 47.01366 0.3958 19.165 5 5 798 0.517 − . d 145.73241 47.01542 0.3972 22.378 3 3 590 0.383 − . e ∗ − . i 145.75700 47.00907 0.4061 19.160 2 3 531 0.344 − . j 145.76435 46.98741 0.41 20.839 2 3 444 0.288 0.70k 145.76440 47.00949 0.39 21.286 1 2 630 0.408 − . LCDCS 0172 a 163.57599 -11.78999 0.6965 22.109 2 3 793 0.911 − . b 163.58247 -11.77602 0.6972 21.651 3 3 485 0.557 0.00c 163.58701 -11.74937 0.6968 22.337 4 3 674 0.774 − . d 163.58728 -11.75391 0.702 20.863 3 3 574 0.659 1.23e 163.60573 -11.76516 0.6977 20.148 1 2 209 0.241 0.13f 163.60592 -11.79784 0.6977 22.885 4 5 685 0.787 0.13g ∗ − . i 163.64143 -11.82147 0.699 21.098 2 2 1650 1.897 0.46MACS J1149.5+2223 a 177.39015 22.40389 0.543 23.162 21.867 2 2 141 0.048 − . b ∗ − . c ∗ − . d 177.39977 22.39728 0.541 21.197 20.223 5 4 155 0.053 − . MACS J1206.2-0847 a 181.53955 -8.81678 0.4356 22.308 21.427 2 2 409 0.202 − . b ∗ − . c 181.57174 -8.80643 0.4450 20.156 19.135 1 1 446 0.220 0.82 Article number, page 19 of 44 &A proofs: manuscript no. aanda
Table 3.
Continued.
LCDCS 0541 a 188.09897 -12.86970 0.5499 21.022 2 3 867 1.008 2.80b 188.10412 -12.86525 0.5399 20.615 2 3 712 0.827 − . c 188.11454 -12.83518 0.5367 19.587 4 1 328 0.382 − . d 188.12779 -12.83268 0.5492 21.795 2 2 249 0.289 2.57e 188.13455 -12.85739 0.5498 20.053 1 2 372 0.432 2.76f 188.14242 -12.81575 0.5323 22.953 1 2 734 0.854 − . g 188.16354 -12.89634 0.5364 21.641 2 3 1482 1.723 − . [MJM98]_034 a ∗ ∗ − . b ∗ − . c 208.55306 -12.55668 0.7627 22.491 2 2 1102 0.693 0.00d ∗ − . f 208.57370 -12.51199 0.7642 24.061 2 1 884 0.556 0.19g 208.57877 -12.51216 0.7634 21.426 2 3 1017 0.640 0.093C 295 a 212.79865 52.20013 0.454 23.593 21.908 1 3 1134 0.634 − . b 212.80549 52.16989 0.43 22.916 1 2 1292 0.722 − . c 212.80823 52.19388 0.4485 22.968 21.459 2 4 977 0.546 − . d 212.82234 52.18692 0.44 23.455 22.452 2 2 791 0.442 − . e 212.82708 52.20480 0.4703 23.794 4 2 530 0.296 1.86f 212.83317 52.19815 0.4659 23.033 3 3 468 0.261 1.07g 212.83551 52.20273 0.464 22.0453 3 4 377 0.211 0.72h 212.85448 52.20978 0.47 25.132 1 2 61 0.034 1.80RX J1532.9+3021 a 233.22410 30.34982 0.3611 17.819 17.108 5 5 7 0.004 3.79MS 1621.5+2640 a 245.89661 26.57446 0.4269 23.106 21.371 3 4 88 0.051 0.18b 245.90057 26.57651 0.4405 22.796 21.103 3 3 136 0.079 2.84c 245.92174 26.53319 0.4071 21.700 2 5 885 0.515 − . RX J1716.4+6708 a 259.15717 67.12481 0.8044 23.235 3 2 1421 0.843 − . MACS J1931.8-2634 a 292.94157 -26.59913 0.3494 20.890 20.158 1 3 491 0.255 − . b 292.9506 -26.57826 0.3652 20.399 20.131 3 4 115 0.060 2.61MS 2053.7-0449 a 314.09464 -4.59867 0.5880 22.293 21.687 2 2 715 0.441 0.81RX J2248.7-4431 a 342.14918 -44.52740 0.3356 21.658 21.043 1 2 569 0.247 − . b 342.15716 -44.54514 0.3312 23.971 22.954 3 2 515 0.224 − . c 342.16731 -44.51396 0.3517 20.443 19.991 5 5 362 0.157 0.70d ∗ − . e 342.20375 -44.54226 0.3552 21.698 21.293 2 2 464 0.202 1.29 Article number, page 20 of 44. Durret et al.: Jellyfish galaxy candidates in medium redshift clusters
Table 4.
CLASH clusters in which the spectral energy distribu-tion (SED) of candidate jellyfish galaxies was analysed. Columnsare: cluster name and number of jellyfish candidates for whichthe SED was analysed.
Cluster
Article number, page 21 of 44 &A proofs: manuscript no. aanda
Appendix A: Images of jellyfish galaxies inMACS J0717.5+3745
The images of our 81 jellyfish galaxy candidates inMACS0717 are shown below. For each galaxy, we indicatethe classifications estimated by two of us in parentheses (asgiven in Table 3).
Appendix B: Images of jellyfish galaxies in allclusters except MACS J0717.5+3745
Article number, page 22 of 44. Durret et al.: Jellyfish galaxy candidates in medium redshift clusters
Fig. A.1.
MACS J0717.5+3745: galaxies &A proofs: manuscript no. aanda
Fig. A.2.
MACS J0717.5+3745: galaxies
Fig. A.3.
MACS J0717.5+3745: galaxies &A proofs: manuscript no. aanda
Fig. A.4.
MACS J0717.5+3745: galaxies
Fig. A.5.
MACS J0717.5+3745: galaxies &A proofs: manuscript no. aanda
Fig. A.6.
MACS J0717.5+3745: galaxies
Fig. A.7.
MACS J0717.5+3745: galaxies &A proofs: manuscript no. aanda
Fig. A.8.
MACS J0717.5+3745: galaxies
Fig. A.9.
MACS J0717.5+3745: galaxies &A proofs: manuscript no. aanda
Fig. B.1.
Cl0016+16 (z=0.5455). All the images are in F814W. Row 1: galaxies a, b and c. Row 2: galaxies d, e and f. Row 3:galaxies g and h.Article number, page 32 of 44. Durret et al.: Jellyfish galaxy candidates in medium redshift clusters
Fig. B.2.
A209 (z=0.206). Row 1: galaxy a in F606W and F814W. Row 2: galaxy b in F606W and F814W.
Fig. B.3.
Cl0152.7-1357 (z=0.831). All the images are in F775W. Row 1: galaxies a, b and c. Row 2: galaxies d, e, and f.Article number, page 33 of 44 &A proofs: manuscript no. aanda
Fig. B.4.
A383 (z=0.1871) in F606W (left) and F814W (right). Row 1: galaxy a, row 2: galaxy b.Article number, page 34 of 44. Durret et al.: Jellyfish galaxy candidates in medium redshift clusters
Fig. B.5.
MACS0416 (z=0.396) in F606W and F814W. Row 1: galaxies a and b. Row 2: galaxies c and d. Row 3: galaxies e andf. Row 4: galaxies g and h (green circle). Article number, page 35 of 44 &A proofs: manuscript no. aanda
Fig. B.6.
MACS0429 (z=0.399) in F606W and F814W. Left: galaxy a, right: galaxy b.
Fig. B.7.
MACS0454 (z=0.5377). All galaxies are in F814W. Row 1: galaxies a, b, and c. Row 2: galaxies d and e.Article number, page 36 of 44. Durret et al.: Jellyfish galaxy candidates in medium redshift clusters
Fig. B.8.
A851 (z=0.4069). All the images are in F814W. Row 1: galaxies a, b and c. Row 2: galaxies d, e and f. Row 3: galaxiesg, h, and i. Row 4: galaxies j and k. Article number, page 37 of 44 &A proofs: manuscript no. aanda
Fig. B.9.
LCDCS0172 (z=0.6972). All the images are in F814W. Row 1: galaxies a, b, and c. Row 2: galaxies d, e, and f. Row 3:galaxies g, h and i.Article number, page 38 of 44. Durret et al.: Jellyfish galaxy candidates in medium redshift clusters
Fig. B.10.
MACS1149 (z=0.544). All the images are in F606W and F814W. Row 1: galaxies a and b. Row 2: galaxies c and d(both are at the cluster redshift, c is to the right).
Fig. B.11.
MACS1206 (z=0.44). All the images are in F606W and F814W. Row 1: galaxies a and b. Row 2: galaxy c.Article number, page 39 of 44 &A proofs: manuscript no. aanda
Fig. B.12.
LCDCS0541 (z=0.5414). All galaxies are in F814W. Row 1: galaxies a, b, and c. Row 2: galaxies d (red circle), e andf. Row 3: galaxy g.
Fig. B.13.
MJM98_034 (z=0.595). Galaxy a in F712W.Article number, page 40 of 44. Durret et al.: Jellyfish galaxy candidates in medium redshift clusters
Fig. B.14.
LCDCS0829 (z=0.451). Galaxy a in F606W and F814W.
Fig. B.15.
LCDCS0853 (z=0.7627). All galaxies are in F814W. Row 1: galaxies a (red circle), b (red circle), and c. Row 2: galaxiesd, e, and f. Row 3: galaxy g. Article number, page 41 of 44 &A proofs: manuscript no. aanda
Fig. B.16.
Fig. B.17.
RX1532 (z=0.345). Images are in F606W and F814W. Left: galaxy a, which is the BCG, showing filaments reminiscentof the Perseus cluster BCG. Right: zoom on galaxy a.
Fig. B.18.
MS1621 (z=0.426). Galaxies a, b, and c in F814W.
Fig. B.19.
RX1716 (z=0.813), galaxy a in F814W.
Fig. B.20.
MACS1931 (z=0.352). Images are in F606W and F814W. Left: galaxy a, right: galaxy b.Article number, page 43 of 44 &A proofs: manuscript no. aanda
Fig. B.21.
MS 2053.7-0449 (z=0.583). Images of galaxy a in F606W (left) and F814W (right).