J/AJ/151/78 Jellyfish galaxy candidates in galaxy clusters (Poggianti+, 2016) ================================================================================ Jellyfish galaxy candidates at low redshift. Poggianti B.M., Fasano G., Omizzolo A., Gullieuszik M., Bettoni D., Moretti A., Paccagnella A., Jaffe Y.L., Vulcani B., Fritz J., Couch W., D'Onofrio M. =2016AJ....151...78P (SIMBAD/NED BibCode) ================================================================================ ADC_Keywords: Clusters, galaxy ; Galaxies, optical ; Redshifts Keywords: atlases - galaxies: clusters: intracluster medium - galaxies: evolution - galaxies: groups: general - galaxies: ISM - galaxies: star formation Abstract: Galaxies that are being stripped of their gas can sometimes be recognized from their optical appearance. Extreme examples of stripped galaxies are the so-called "jellyfish galaxies" that exhibit tentacles of debris material with a characteristic jellyfish morphology. We have conducted the first systematic search for galaxies that are being stripped of their gas at low-z (z=0.04-0.07) in different environments, selecting galaxies with varying degrees of morphological evidence for stripping. We have visually inspected B- and V-band images and identified 344 candidates in 71 galaxy clusters of the OMEGAWINGS+WINGS sample and 75 candidates in groups and lower mass structures in the PM2GC sample. We present the atlas of stripping candidates and a first analysis of their environment and their basic properties, such as morphologies, star formation rates and galaxy stellar masses. Candidates are found in all clusters and at all clustercentric radii, and their number does not correlate with the cluster velocity dispersion {sigma} or X-ray luminosity L_X_. Interestingly, convincing cases of candidates are also found in groups and lower mass halos (10^11^-10^14^M_{sun}_), although the physical mechanism at work needs to be securely identified. All the candidates are disky, have stellar masses ranging from log M/M_{sun}_<9 to >11.5 and the majority of them form stars at a rate that is on average a factor of 2 higher (2.5{sigma}) compared to non-stripped galaxies of similar mass. The few post-starburst and passive candidates have weak stripping evidence. We conclude that disturbed morphologies suggestive of stripping phenomena are ubiquitous in clusters and could be present even in groups and low mass halos. Further studies will reveal the physics of the gas stripping and clarify the mechanisms at work. Description: WIde-field Nearby Galaxy-cluster Survey (WINGS) is a large survey targeting 76 clusters of galaxies selected on the basis of their X-ray luminosity (Ebeling et al. 1996, Cat. J/MNRAS/281/799; Ebeling et al. 1998, Cat. J/MNRAS/301/881; Ebeling et al. 2000, Cat. J/MNRAS/318/333), covering a wide range in cluster masses ({sigma}=500-1200+km/s, logL_X_=43.3-45erg/s, Fasano et al. 2006A&A...445..805F). The original WINGS data set consisted of B and V deep photometry of a 34'*34' field of view with the WFC@INT and the WFC@2.2mMPG/ESO (Varela et al. 2009, Cat. J/A+A/497/667), spectroscopic follow-ups with 2dF@AAT and WYFFOS@WHT (Cava et al. 2009, Cat. J/A+A/495/707), plus J and K imaging with WFC@UKIRT (Valentinuzzi et al. 2009, Cat. J/A+A/501/851) and some U-band imaging (Omizzolo et al. 2014, Cat. J/A+A/561/A111). This database is presented in Moretti et al. 2014A&A...564A.138M and has been employed for a number of studies (see https://sites.google.com/site/wingsomegawings/). OmegaCAM-VST observations of WINGS galaxy clusters (OMEGAWINGS) is a recent extention of this project, that quadruples the area covered (1deg^2^) and allows to reach up to ~2.5 cluster virial radii. OMEGAWINGS is based on two OmegaCAM@VST GTO programs for 46 WINGS clusters: a B and V campaign completed in P93, and an ongoing u-band programme. The B and V data, the data reduction and the photometric catalogs are presented in Gullieuszik et al. 2015 (Cat. J/A+A/581/A41). Spectra are obtained with AAOmega@AAT on the OmegaCAM field. So far, we have secured high quality spectra for ~30 OMEGAWINGS clusters, reaching very high spectroscopic completeness levels for galaxies brighter than V=20 from the cluster cores to their periphery (A. Moretti et al. 2016, in preparation). Galaxies are considered cluster members if they are within 3{sigma} from the cluster redshift. The mean redshift uncertainty, computed from the differences between WINGS and OMEGAWINGS redshift values of repeated objects, is {Delta}z=0.0002. For this paper we consider the 41 OMEGAWINGS clusters with an OmegaCAM B and/or V-band seeing {<=}1.2arcsec, listed in Table1. To complete the search within the WINGS sample, we used the old WINGS images for other 31 clusters not observed with OmegaCAM (Table1). The reference comparison field sample for WINGS and OMEGAWINGS is the Padova Millennium Galaxy and Group Catalog (PM2GC; Calvi et al. 2011, Cat. J/MNRAS/416/727), built from the Millennium Galaxy Catalogue (MGC; Liske et al. 2003, Cat. VII/240), a deep 38deg^2^ INT B-imaging survey with a highly complete spectroscopic follow-up (96% at B=20, Driver et al. 2005, Cat. VII/240). File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table1.dat 35 71 *OMEGAWINGS (O) and WINGS (W) clusters table3.dat 86 344 *OMEGAWINGS and WINGS stripping candidates table4.dat 57 75 *PM2GC stripping candidates -------------------------------------------------------------------------------- Note on table1.dat table3.dat: WINGS = WIde-field Nearby Galaxy-cluster Survey (Fasano et al. 2006A&A...445..805F); OMEGAWINGS = OmegaCAM-VST observations of WINGS galaxy clusters (Gullieuszik et al. 2015, Cat. J/A+A/581/A41). Note on table4.dat: PM2GC = Padova-Millennium Galaxy and Group Catalogue (Calvi et al. 2011, Cat. J/MNRAS/416/727). -------------------------------------------------------------------------------- See also: V/139 : The SDSS Photometric Catalog, Release 9 (Adelman-McCarthy+, 2012) VII/240 : Millennium Galaxy Catalogue (Liske+, 2003) J/A+A/581/A41 : OmegaWINGS photometry of gal. clusters (Gullieuszik+, 2015) J/A+A/561/A111 : U-band photometry of 17 WINGS clusters (Omizzolo+, 2014) J/ApJ/762/77 : PM2GC sample surface photometry (Poggianti+, 2013) J/MNRAS/432/3141 : Morphological classification of PM2GC gal. (Calvi+, 2013) J/MNRAS/420/926 : Morphology of galaxies in WINGS clusters (Fasano+, 2012) J/MNRAS/416/727 : Padova-Millennium Galaxy and Group Catalogue (Calvi+, 2011) J/A+A/526/A45 : WINGS-SPE II catalog (Fritz+, 2011) J/A+A/501/851 : WINGS photometry of 28 galaxy clusters (Valentinuzzi+, 2009) J/A+A/497/667 : WINGS: Deep optical phot. of nearby clusters (Varela+, 2009) J/A+A/495/707 : WINGS spectroscopy of 48 galaxy clusters (Cava+, 2009) J/MNRAS/318/333 : Extended ROSAT Bright Cluster Sample (Ebeling+ 2000) J/MNRAS/301/881 : The ROSAT brightest cluster sample - I. (Ebeling+, 1998) J/MNRAS/281/799 : XBACs, the sample (Ebeling+, 1996) Byte-by-byte Description of file: table1.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1 A1 --- Sample [OW] Sample (O=OMEGAWINGS or W=WINGS) (1) 3- 9 A7 --- Cluster Name of the galaxy cluster 11 A1 --- f_Cluster [*] Flag on Cluster: *=member of Shapley supercluster (2) 13- 18 F6.4 --- z [0.039/0.07] Redshift 20- 23 I4 km/s sigma [353/1309]? Cluster velocity dispersion {sigma} 25- 26 I2 km/s e_sigma [10/97]? Uncertainty in {sigma} 28- 32 F5.2 [10-7J/s] logLx [43.5/45.1] Log(L_X_) in 0.1-2.4keV band 34- 35 I2 --- Nc [1/15] Number of stripping candidates (spectroscopic member or possible member, i.e., without redshift) -------------------------------------------------------------------------------- Note (1): WINGS (Cava et al. 2009, Cat. J/A+A/495/707) or OMEGAWINGS (Moretti et al. in prep.). Note (2): See Shapley in Simbad database. -------------------------------------------------------------------------------- Byte-by-byte Description of file: table3.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 5 A5 --- Galaxy Jellyfish galaxy identifier (JW prefix for WINGS clusters and JO for OMEGAWINGS clusters) (1) 7- 13 A7 --- Cluster Galaxy cluster 15 A1 --- Img [OW] Inspected image: O=OMEGAWINGS (OmegaCAM) or W=WINGS (INT or 2.2m) (2) 17 A1 --- Band [BV] Inspected image bandpass (B or V) 19- 29 F11.7 deg RAdeg Right Ascension decimal degrees (J2000) 31- 41 F11.7 deg DEdeg Declination decimal degrees (J2000) 43 I1 --- J [1/5] JClass (visual evidence for stripping signatures in the optical) (G1) 45- 73 A29 --- n_Galaxy Comments on Jellyfish identifier 75- 76 I2 --- Mm [-1/2] Cluster membership (1=member, 0=non-member, -1=redshift unknown) (3) 78- 84 F7.5 --- z [0.0074/0.27]? Redshift 86 A1 --- r_z Source for redshift (1=WINGS or OMEGAWINGS, 2=NED, 3=SDSS, or 4=average NED and SDSS) (4) -------------------------------------------------------------------------------- Note (1): Galaxies that are being stripped of their gas can sometimes be recognized from their optical appearance. Extreme examples of stripped galaxies are the so-called "jellyfish galaxies" that exhibit tentacles of debris material with a characteristic jellyfish morphology. Note (2): WINGS data set of B and V deep photometry of a 34'*34' field of view with the WFC@INT and the WFC@2.2mMPG/ESO (Varela et al. 2009, Cat. J/A+A/497/667); OMEGAWINGS is based on two OmegaCAM@VST GTO programs for 46 WINGS clusters, including a B and V campaign completed in P93. Note (3): Cluster membership: 1 = member; 0 = non-member; 2 = member of structure along the line of sight; -1 = redshift unknown. Note (4): Source of redshift: 1 = WINGS (Cava et al. 2009, Cat. J/A+A/495/707) or OMEGAWINGS (Moretti et al. in prep.); 2 = NED (https://ned.ipac.caltech.edu/); 3 = SDSS (see SDSS-DR9 in Cat. V/139); 4 = Average NED and SDSS. -------------------------------------------------------------------------------- Byte-by-byte Description of file: table4.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 5 I5 --- MGC [648/96949] Galaxy identifier in Millennium Galaxy Catalog (MGC; Liske et al. 2003, Cat. VII/240) 7- 15 F9.5 deg RAdeg Right Ascension in decimal degrees (J2000) 17- 24 F8.5 deg DEdeg Declination in decimal degrees (J2000) 26 I1 --- J [1/4] JClass (visual evidence for stripping signatures in the optical) (G1) 28- 34 F7.5 --- z [0.04/0.07] MGC redshift (Liske et al. 2003, Cat. VII/240) 36- 57 A22 --- Comment Comments on visual appearance -------------------------------------------------------------------------------- Global Notes: Note (G1): Ranges from 5 (strongest) to 1 (weakest). -------------------------------------------------------------------------------- History: From electronic version of the journal ================================================================================ (End) Prepared by [AAS]; Sylvain Guehenneux [CDS] 13-Oct-2016