Astronomy&Astrophysicsmanuscriptno.AA23111 (cid:13)cESO2014 January15,2014 SDSS superclusters: morphology and galaxy content M.Einasto1,H.Lietzen1,2,3,E.Tempel1,4,M.Gramann1,L.J.Liivamägi1,5,andJ.Einasto1,6,7 1 TartuObservatory,61602Tõravere,Estonia 2 InstitutodeAstrofísicadeCanarias,E-38200LaLaguna,Tenerife,Spain 3 UniversidaddeLaLaguna,Dept.Astrofísica,E-38206LaLaguna,Tenerife,Spain 4 NationalInstituteofChemicalPhysicsandBiophysics,Rävalapst10,Tallinn10143,Estonia 5 InstituteofPhysics,TartuUniversity,Tähe4,51010Tartu,Estonia 6 EstonianAcademyofSciences,EE-10130Tallinn,Estonia 4 7 ICRANet,PiazzadellaRepubblica10,65122Pescara,Italy 1 Received/Accepted 0 2 n ABSTRACT a J Context.Understandingtheformation,evolutionandpresent-daypropertiesofthecosmicwebandobjectsformingitisanimportant taskincosmology. 4 Aims.We compare the galaxy populations in superclusters of different morphology in the nearby Universe (180 h−1Mpc ≤ d ≤ 1 270h−1Mpc)toseewhethertheinnerstructureandoverallmorphologyofsuperclustersareimportantinshapinggalaxyproperties insuperclusters. ] O Methods.WefindsuperclustermorphologywithMinkowskifunctionalsandanalysetheprobabilitydensitydistributionsofcolours, morphologicaltypes,stellarmasses,starformationrate(SFR)ofgalaxies,andthepeculiarvelocitiesofthemaingalaxiesingroups C insuperclustersoffilamentandspidertypes,andinthefield.WetestthestatisticalsignificanceoftheresultswiththeKStest. . Results.Thefractionofred,early-type,lowSFRgalaxiesinfilament-typesuperclustersishigherthaninspider-typesuperclusters;in h low-densityglobalenvironmentstheirfractionislowerthaninsuperclusters.Inallenvironmentsthefractionofred,highstellarmass, p andlowSFRgalaxiesinrichgroupsishigherthaninpoorgroups.Insuperclustersofspidermorphologyred,highSFRgalaxieshave - o higherstellarmassesthaninfilament-typesuperclusters.Groupsofequalrichnesshostgalaxieswithlargerstellarmasses,alarger r fraction of early-type and red galaxies, and ahigher fraction of low SFR galaxies, if they arelocated insuperclusters of filament t morphology. The peculiar velocities of the main galaxies in groups from superclusters of filament morphology are higher than in s a thoseofspidermorphology.Groupswithhigherpeculiarvelocitiesoftheirmaingalaxiesinfilament-typesuperclustersarelocatedin [ higherdensityenvironmentthanthosewithlowpeculiarvelocities.Therearesignificantdifferencesbetweengalaxypopulationsof theindividualrichestsuperclusters. 1 Conclusions.Bothlocal(group)andglobal(supercluster)environmentsandevensuperclustermorphologyplayanimportantrolein v theformationandevolutionofgalaxies.Differencesintheinnerstructureofsuperclustersoffilamentandspidermorphologyandthe 6 dynamicalstateofgalaxygroupsinthemmayleadtothedifferencesfoundinourstudy. 2 2 Keywords. Cosmology:Large-scalestructureoftheUniverse;galaxies:groups:general;Methods:statistical 3 . 1 01. Introduction richer,andtheycontainalargerfractionofred,non-starforming 4 galaxiesthanpoorsuperclusters(Einastoetal.2007a,b). 1ThelargescalestructureoftheUniverseisformedbyahierar- :chy of galaxy systems from isolated galaxies to groups, clus- Early studies of galaxy environment showed that environ- v iters, and superclusters of galaxies. Galaxy superclusters, en- ments at the group and cluster scale affects the morphology Xvironments for galaxies, and groups and clusters of galaxies, of galaxies, early-type, more luminous galaxies are located rare the largest relatively isolated systems in the Universe are in higher density environments than late-type, fainter galax- agalaxysuperclusters(deVaucouleurs1956;Jõeveeretal. 1978; ies(Einastoetal.1974;Dressler1980;Postman&Geller1984; Einastoetal.1984,1994;Zuccaetal.1993).Tounderstandthe Einasto&Einasto1987;Hamilton1988;Einasto1991).Theen- role of small-scale (group) and large-scale (supercluster) envi- vironmentaffectsthepropertiesofgalaxiesandgroupsofgalax- ronments in galaxy formation and evolution, we need to study iesevenatlargerscales,upto10–15h−1Mpc(Einasto&Einasto thepropertiesofsuperclustersandtheirgalaxyandgrouppopu- 1987; Moetal. 1992; Einastoetal. 2003a,b; Skibba 2009; lationstogether. Tempeletal. 2011). In addition, groups of the same richness Withthe adventofdeepsurveyscoveringlargeareasin the containalargerfractionofred,non-star-forminggalaxiesifthey sky it became possible to determine the parameters of a large are located in rich superclusters compared to groups in poor number of superclusters, and to study in detail the galaxy and superclusters or in low-density large-scale environments out- group populations in them. These studies have revealed that side of superclusters (Einastoetal. 2008; Lietzenetal. 2012). in richer superclusters groups and clusters of galaxies are also Luparelloetal. (2013) showed that the stellar population of galaxiesingroupsinsuperstructuresissystematicallyolder,and groups themselves are larger and have higher velocity disper- Sendoffprintrequeststo:M.Einasto sionsthangroupswhichdonotbelongtosuperstructures. Articlenumber,page1of14 A&Aproofs:manuscriptno.AA23111 Themorphologyofsuperclustershavebeenstudied,forex- We calculate the galaxy luminosity density field to recon- ample,byCosta-Duarteetal.(2011)andEinastoetal.(2007c). struct the underlying luminosity distribution and to determine Galaxysuperclustershavecomplexinnerstructuresthatcan be superclusters (extended systems of galaxies) in the luminosity quantified with morphological descriptors as Minkowski func- densityfieldatsmoothinglength8h−1MpcusingB splineker- 3 tionals.Einastoetal.(2007c,2011a)foundinthewidemorpho- nel (see Einastoetal. 2007c, for comparison between B and 3 logicalvarietyofsuperclusterstwomaintypesofsuperclusters: Gaussiankernel).Wecreatedasetofdensitycontoursbychoos- filaments and spiders. In filaments high-density core(s) of su- ingadensitythresholdsanddefinedconnectedvolumesabovea perclusters are connected by a small number of galaxy chains certain density threshold as superclusters. In order to choose a (filaments). In spiders there are many galaxy chains between proper density level to determine individual superclusters, we high-densitycoresinsuperclusters.Poorspider-typesuperclus- analysed the properties of the density field superclusters at a ters are similar to our Local supercluster with one rich cluster series of density levels. As a result we used the density level andfilamentsofgalaxiesandpoorgroupsofgalaxiesaroundit D = 5.0(inunitsofmeandensity,ℓ = 1.65·10−2 1010h−2L⊙) (Einastoetal.2007c). 8 mean (h−1Mpc)3 todetermineindividualsuperclusters(Liivamägietal.2012).At Einastoetal. (2012a) analysed the structure of rich galaxy this density level superclusters in the richest chains of superclusters in superclusters of different morphologiesand showed clusters in the volume under study still form separate systems; thatclusters in superclustersof spider morphologyhave higher atlower densitylevelstheyjoin into hugepercolatingsystems. probabilitiesofhavingsubstructureandtheirmaingalaxieshave Athigherthresholddensitylevelssuperclustersaresmallerand higher peculiar velocities than clusters in superclusters of fila- theirnumberdecreases. mentmorphology. The morphologyof all superclustersused in this study was Inthepresentstudywecontinueouranalysisofsuperclusters determinedin Einastoetal. (2012a) applyingMinkowskifunc- ofdifferentmorphology,studyingtheirgalaxyandgrouppopu- tionals.Fora givensurfacethe fourMinkowskifunctionalsare lations, to understand better how the large-scale (supercluster) proportionalto the enclosed volume V, the area of the surface environmentaffectsthepropertiesofgalaxiesandgroupsresid- S,theintegratedmeancurvatureC,andtheintegratedGaussian inginthem.Forcomparisonwealsoanalysegalaxycontentand curvature χ (see Appendix B and Einastoetal. 2007c, 2011a, grouppropertiesinlow-densityglobalenvironment(field). fordetailsandreferences).Theoverallmorphologyof a super- In Sect. 2 we describe the data about galaxies, groups, and cluster is described by the shapefinders K (planarity) and K 1 2 superclustersusedinthispaper,inSect.3wecomparethegalaxy (filamentarity),andtheirratio,K /K (theshapeparameter),cal- 1 2 contentandthepeculiarvelocitiesofthemaingalaxiesingroups culated using the first three Minkowski functionals. The lower insuperclustersofdifferenttype,andinthefield.Wediscussthe thevalueoftheshapeparameter,themoreelongatedasuperclus- resultsanddrawconclusionsinSect.4. ter is. The maximumvalueof the fourthMinkowskifunctional Weassumethestandardcosmologicalparameters:theHub- V characterises the inner structure of the superclusters. The ble parameter H = 100 h km s−1 Mpc−1, the matter den- 3 0 higherthevalueofV ,themorecomplicatedtheinnermorphol- sity Ω = 0.27, and the dark energy density Ω = 0.73 3 m Λ ogyofasuperclusteris(Einastoetal.2007c,2011b).Superclus- (Komatsuetal.2011). terswereclassifiedasfilamentsandspidersonthebasisoftheir morphologicalinformationandvisualappearance.Superclusters showwidemorphologicalvarietyinwhichEinastoetal.(2011a) 2. Data determined four main morphological types: spiders, multispi- 2.1.Galaxy,group,andsuperclusterdata ders,filaments,andmultibranchingfilaments.Spidersandmulti- spidersaresystemsofoneorseveralhigh-densityclumpswitha We use the MAIN sample of the 8th data release of the Sloan number of outgoing filaments connecting them. Filaments and Digital Sky Survey (SDSS DR8) (Aiharaetal. 2011) with the multibranching filaments are superclusters with filament-like apparentGalactic extinctioncorrectedr magnitudesr ≤ 17.77, mainbodiesthatconnectclustersinsuperclusters.Forsimplicity, andtheredshifts0.009≤z≤0.200,intotal576493galaxies.We in thisstudywe classify superclustersas spidersandfilaments. correctedtheredshiftsofgalaxiesforthemotionrelativetothe InAppendixBweshowanexamplesoffilamentandspider-type CMBandcomputedthe co-movingdistances(Martínez&Saar superclusters. 2002)ofgalaxies. The description of the supercluster catalogues is given in Galaxy groups were determined using the Friends-of- Liivamägietal. (2012), the details of supercluster morphology Friends cluster analysis method introduced in cosmology by aregiveninEinastoetal.(2007c,2011a). Zeldovichetal. (1982) and Huchra&Geller (1982). A galaxy Figure 1 presents the distribution of rich galaxy clusters belongs to a group of galaxies if this galaxy has at least one in superclusters of filament and spider morphology,as well as group member galaxy closer than a linking length. In a flux- from the field in cartesian coordinates x, y, and z defined as in limitedsamplethedensityofgalaxiesslowlydecreaseswithdis- Parketal.(2007)andinLiivamägietal.(2012): tance. To take this selection effect into account properly when constructing a group catalogue from a flux-limited sample, we x=−dsinλ, rescaledthelinkinglengthwithdistance,calibratingthescaling y=dcosλcosη, relationbyobservedgroups(see Tagoetal.2008,2010,forde- z=dcosλsinη, tails).Asaresult,themaximumsizesintheskyprojectionand thevelocitydispersionsofourgroupsaresimilaratalldistances. wheredisthefingerofgodcorrectedcomovingdistance,andλ Ourinitialsampleischoseninthedistanceinterval120h−1Mpc andηaretheSDSSsurveycoordinates. ≤ d ≤340h−1Mpc(theredshiftrange0.04 < z < 0.09)where Up to distances of about 180 h−1Mpc the SDSS survey the selection effects are the smallest (we discuss the selection crosses the void region between the Hercules supercluster and effects in detail in Tagoetal. 2010; Einastoetal. 2012a). The the chain of rich superclusters farther away (the Bootes void, details of data reduction and the description of the group cata- Kirshneretal. 1981). Two chains of galaxies, groups, and su- loguecanbefoundinTempeletal.(2012). perclusters cross this void. At the distance interval of about Articlenumber,page2of14 M.Einastoetal.:Sclgal 300 red,scl 2000 blue,scl c/h)200 1500 p al M g _ y ( N1000 100 500 −300 −200 −100 0 100 200 300 0 x (Mpc/h) 150 200 250 300 D (Mpc/h) 100 10000 red,field blue,field h) 8000 c/ p 0 M z ( _gal6000 N 4000 −100 2000 −300 −200 −100 0 100 200 300 0 x (Mpc/h) 150 200 250 300 Fig.1. Distributionofgalaxygroupswithatleastfourmembergalax- D (Mpc/h) iesinsuperclustersin x,y,andzcoordinates.Redfilledcirclescorre- Fig.2. Thedistributionofdistancesofredandbluegalaxies(redand spondtogroupsinfilament-typesuperclusters.Blueemptycirclesde- bluelines,respectively)insuperclusters(upper panel)andinthefield note groups in spider-type superclusters. Grey crosses denote groups (lowerpanel). withatleast30membergalaxiesfromthefield. culationsshowedthattheresultsforthenearanddistantsamples 180 h−1Mpc ≤ d ≤ 270 h−1Mpc the survey crosses a number aresimilar,butthestatisticsofthenearsamplearenotveryreli- of rich superclusters, including the Sloan Great Wall (detailed able,thereforeinthepaperwepresentourresultsforthedistant descriptionofthelarge-scaledistributionofsuperclusterscanbe sampleonly. foundin Einastoetal. 2011b,a). Atdistancesd > 270h−1Mpc thereisanothervoidregion,andthefrequencyofsuperclusters Table1.Numberofgalaxiesinfilamentandspider-typesuperclusters inthisregionisverylow.ThisisalsoseeninFig.2whereweplot andinfieldforflux-andvolume-limitedsamples. thedistributionsofdistancestoredandbluegalaxiesdividedby theircolourindexg−r=0.7(seeSect.2.2)insuperclustersand 120−180h−1Mpc 180−270h−1Mpc inthefield. Sample flux-lim vol-lim flux-lim vol-lim We have different distance intervals with different large- Filaments 517 500 8102 6664 scaledistributionsandrichnessofsystems.Fromtheseweanal- Spiders 3497 3024 12030 9211 ysed data from two regions: a void region with poor systems, Field 58712 50643 123230 93795 120 h−1Mpc ≤ d ≤ 180 h−1Mpc (near sample), and a super- clusterregionwithrichsystemsofgalaxies180h−1Mpc≤ d ≤ 270h−1Mpc(distantsample).Amongthe50superclustersstud- ied, 35 are of spider morphology and 15 of filament morphology. The supercluster data are given in Table A.1. We do not 2.2.Galaxyproperties use data for very poor superclusters without any rich clusters whosemorphologyisdifficulttodetermine(fordetailswerefer Inthepresentpaperweusetheg−rcoloursofgalaxiesandtheir toEinastoetal.2012a). absolutemagnitudesinther-bandMr.Theabsolutemagnitudes ofindividualgalaxiesarecomputedaccordingtotheformula Our data are based on a flux-limited sample of galaxies in which absolute magnitude limit increases with distance, intro- M =m −25−5log (d )−K, (1) ducing selection effects: there are relatively more red galaxies r r 10 L at great distances (this can also be seen in Fig. 2). In order to whered istheluminositydistanceinunitsofh−1MpcandK is L avoidthisselectioneffectweusedvolume-limitedsampleswith the k+e-correction. The k-corrections were calculated with the M ≤ −18.5 in near samples, and M ≤ −19.5 in distant sam- KCORRECT(v4_2) algorithm (Blanton&Roweis 2007) and r r ples. The numbers of galaxies in near and distant samples of the evolution corrections have been calibrated according to superclusters are given in Table 1. The number of galaxies in Blantonetal.(2003).Weuse M = 4.53(inr-filter).Allofour ⊙ filament-typesuperclustersfromnearsampleis small.Our cal- magnitudesandcolourscorrespondtotherest-frameatredshift Articlenumber,page3of14 A&Aproofs:manuscriptno.AA23111 z = 0. The value g−r = 0.7 is used to separate red and blue phology,and from the field. We show the distributionsof late- galaxies,redgalaxieshavingg−r ≥0.7.Weusedthemorphol- typegalaxiesonly;thedistributionsofearly-typegalaxiesshow ogyclassificationbyHuertas-Companyetal.(2011)whichgives similardifferencesbetweengalaxypopulations(p =1−p).The e l foreachgalaxyaprobabilityofbeingearlyandlatetype,p and valuesofquantilesofgalaxyparametersaregiveninTableC.1. e p, correspondingly.Approximately,we calla galaxylate type, l if pl >0.5,andearlytype,if pe >0.5. 4 F To study the stellar masses logM and SFRs, we use 6 F S s S Field the MPA-JHU spectroscopic catalogue (Tremontietal. 2004; 5 Field 3 Brinchmannetal. 2004). In this catalogue the differentproper- 4 ties of galaxies are obtained by fitting SDSS photometry and d d 2 spectra with the stellar population synthesis models developed 3 byBruzual&Charlot(2003).Thestellarmassesofgalaxiesare 2 1 derived in the manner described by Kauffmannetal. (2003). 1 For the DR8 data the stellar masses are estimated from the 0 0 galaxy photometry (rather than the spectral indices Dn4000 0.2 0.4 0.6 0.8 1.0 0.0 0.2 0.4 0.6 0.8 1.0 and Hδ used by Kauffmannetal. 2003). The SFRs are com- 1.5 g − r p _l puted using the photometry and emission lines as described FS 0.75 FS by Brinchmannetal. (2004) and Salimetal. (2007). For active 1.25 Field Field galacticnucleiandgalaxieswithweakemissionlines,SFRsare 1.0 estimated from the photometry. For star-forming galaxies with 0.5 d0.75 d strongemissionlines,theSFRsareestimatedbyfittingdifferent emissionlinesinthegalaxyspectrum(Hα,Hβ,[Oiii]5007,[Nii] 0.50 0.25 6584,[Oii]3727,[Sii] 6716).Thestellar massesandSFRs are 0.25 takenfromtheSDSSCASdatabase. 0.0 0.0 Inthegroupcataloguethemaingalaxyofagroupisdefined 9.0 9.5 10.0 10.5 11.0 11.5 12.0 −2.0 −1.0 0.0 1.0 asthemostluminousgalaxyinther-band.Wealsousethisdef- M_star SFR initioninthepresentpaper.Invirializedclustersgalaxiesfollow Fig.3. Probabilitydensitydistributionsofgalaxyg−rcolours(upper theclusterpotentialwell,andsowewouldexpectthatthemain leftpanel),probabilitiesofbeinglatetype(p,upperrightpanel),stellar l galaxiesinclusterslieatthecentresofgroupsandhavelowpe- masses(logM inlog M ,lowerleftpanel),andstarformationsrates s ⊙ culiarvelocities(Ostriker&Tremaine1975).Thereforethepe- (SFRs,inlog M /yr) forgalaxies inthesuperclusters of filament and ⊙ culiar velocity of the main galaxies in clusters is also an indi- spidermorphologyandinthefield. cation of the dynamicalstate of the cluster (Cozioletal. 2009; Einastoetal.2012b).Wecalculatethepeculiarvelocitiesofthe Thisfigureshows,firstofall,thatgalaxypopulationsinsu- maingalaxies,|v |,andcomparethesevelocitiesforgroupsin perclusters and in the field are different, superclusters contain- pec superclustersofdifferentmorphology,andinthefield. ing a larger fraction of red, early-type, high stellar mass, and low SFR galaxies than can be found in the field. These fig- ures show that galaxy populations in superclusters of filament 3. Results and spider morphology are also different, superclusters of filament morphologycontain a larger fraction of red, early-type, 3.1.Superclustersofdifferentmorphology low SFR galaxiesthan superclustersof spider morphology.All We analyse galaxy populations in superclusters of different differences are statistically significant at very high confidence morphology, and in the field using probability density distri- level(pKS <0.001). butions which are calculated within the statistical package R The distribution of stellar masses of galaxies in filament environment using the ’density’ command in the ’stats’ pack- andspider-typesuperclustersshowsthatinfilament-typesuper- age (Ihaka&Gentleman 1996) 1. In Tables in Appendix C we clusters there is some deficit of low stellar mass galaxies with presentthevaluesofquantilesoftheparametersanalysedinthe logMs < 10.25, and relatively more galaxies of higher stel- paper. The distributionsof colours, probabilitiesof being early lar mass than in superclusters of spider morphology. In Fig. 4 orlatetype,stellarmasses,andSFRsarebimodalorasymmetri- we show the probabilitydensitydistributionsof colours,types, cal;theuseoffulldistributionsintheanalysisandquantileval- and SFRs of high and low stellar mass galaxies in superclus- uesinTablesisstraightforward.Tonottomaketablestooover- ters of filament and spider type. Table C.2 presents the values crowdedwedonotincludeerrorstothetables;thestatisticalsig- ofquantilesoftheseparameters.Asexpected(see,forexample, nificance of the differencesbetween differentgalaxyproperties Blanton&Moustakas 2009), among high stellar mass galaxies have been found using the full data (the integral distributions) therearerelativelymorered,early-type,lowSFRgalaxiesthan andtheKolmogorov-Smirnov(KS)test.Wegivethe p -values amonglowstellarmassgalaxies.Interestingly,thisfigureshows KS ofthetest,throughoutthepaper(fordetailsofthisapproachwe thatlowstellarmassgalaxiesinfilament-typesuperclustersare refer to Einastoetal. 2008). We consider that the differences mainly blue, but in spider-type superclusters there is relatively betweendistributionsarehighlysignificantifthe p value(the moreredgalaxiesamongthemincomparisonwithfilament-type KS estimated probability of rejecting the hypothesis that distribu- superclusters. These differences are statistically highly signifi- tionsarestatisticallysimilar) p ≤0.05. cant, as also differences in galaxy types. Differences between KS Figure 3 present the distributions of galaxy g − r colours, SFRsofgalaxiesfromfilamentandspider-typesuperclustersdi- probabilitiesofbeinglatetype(p),stellarmasses(logM ),and videdbystellarmassarelowandstatisticallyunsignificant,ac- l s SFRsforgalaxiesfromsuperclustersoffilamentandspidermor- cordingtotheKStest. Next we divided galaxies by colours and SFRs as red, low 1 http://www.r-project.org SFRgalaxies(g−r ≥ 0.7,andlogSFR < −0.5,approximately Articlenumber,page4of14 M.Einastoetal.:Sclgal F,h 5 F,h F,h F,l F,l 1.5 F,l 5 S,h S,h S,h S,l S,l S,l 1.0 d d d 2.5 2.5 0.5 0 0 0.0 0.2 0.4 0.6 0.8 1.0 0.0 0.2 0.4 0.6 0.8 1.0 −2.0 −1.0 0.0 1.0 g − r p_l SFR Fig.4. Probabilitydensitydistributionsofgalaxyg−rcolours(leftpanel),probabilitiesofbeinglatetype(p,middlepanel),andstarformations l rates(SFRs,inlog M /yr,rightpanel)forhigh(h,logM ≥ 10.25,solidlines)andlow(l,logM < 10.25,dashedlines)stellarmassgalaxiesin ⊙ s s thesuperclustersoffilament(F,redlines)andspider(S,bluelines)morphology. 60% of all galaxies), blue, high SFR galaxies (g − r < 0.7, 0.008 0.020 F and logSFR ≥ −0.5, 30% of all galaxies), and red, high SFR S F galaxies (g−r ≥ 0.7, and logSFR ≥ −0.5, 10% of all galax- 0.006 S 0.015 ies).Weplotthedistributionsoftheirstellarmassesandtypesin d0.004 d0.010 Fig.5,andgivethevaluesofquantilesofthestellarmassesand typesinTableC.3.Thisfigureshowsinterestingfeature:stellar 0.002 0.005 massesofred,lowSFRgalaxies,andblue,highSFRgalaxiesin filament-typesuperclustersarehigherthaninspider-typesuper- 0.0 0.0 clusters, as were these masses in overall distributions (Fig. 3), 0 200 400 600 800 0 100 200 300 but stellar masses of red, high SFR galaxies have higher val- D1 D2 ues in spider-type superclusters. In filament-type superclusters 0.25 their stellar masses are close to the stellar masses of red, low 0.05 F SFR galaxies, in spider-type superclusters their stellar masses 0.04 FS 0.20 S areevenhigherthanthoseofred,lowSFRgalaxies.Thesegalax- 0.15 0.03 iesaremostlyoflatetype.Thusthisfigureshowsthathighmass d d galaxiesare red, evenif they are of high SFR and of late type, 0.02 0.10 andthereisadifferenceintheirmassesindifferenttypesofsu- 0.01 0.05 perclusters. KS test shows that the differences between stellar 0.0 0.0 masses and types of high and low SFR galaxies from filament 0 25 50 75 100 0 5 10 15 20 25 and spider-type superclusters are statistically highly significant D4 D8 forbothhighandlowSFRredgalaxies. Fig.6. Distributionsofenvironmentaldensitiesatdifferentsmoothing lengths(1,2,4,and8h−1Mpc)insuperclustersoffilament(redlines) 1.5 6 rbelude, ,l ohwig hS FSRF,R F andspider(bluelines)morphology. red, high SFR red, low SFR, S 1.0 4 brelude, ,h higighh S SFFRR superclusters,theKStestshowsthatthedifferencesarestatisti- d d callysignificantatleast95%level.Ifdensitiesin filament-type 0.50 2 superclustersweresystematicallyhigherthaninspider-typesuperclusters then the differences between galaxy populations in 0.0 0 thesesuperclusterswererelatedtothedependenceofthegalaxy 9.5 10.0 10.5 11.0 11.5 0.0 0.2 0.4 0.6 0.8 1.0 morphologyontheenvironmentaldensity,butweseethatthisis M_s p_l notso.Innermorphologyofsuperclustersisimportant. Fig. 5. Probability density distributions of stellar masses (logM, in s We also calculated environmental densities around galax- logM ),(leftpanel)andprobabilitiesofbeinglatetype(p,rightpanel), ⊙ l iesofdifferentcolourandSFRs.Figure7showsenvironmental for red, low SFR galaxies (red lines), blue, high SFR galaxies (blue lines),andforred,highSFRgalaxies(greylines)inthesuperclustersof densities at 8 h−1Mpc smoothing length around red, low SFR, filament(solidlines)andspider(dashedlines)morphology.HighSFR blue,highSFR,andred,highSFRgalaxies,analysedabove.In galaxieshavelogSFR ≥ −0.5,andlowSFRgalaxieshavelogSFR < this figure we see that blue, high SFR galaxies have somewhat −0.5.Linesintheleftpaneldenotethesamepopulationsasintheright lower environmental densities around them than red, low SFR panel. galaxiesin both type of superclusters. This is an evidence of a large-scale morphology-density relation. Environmental densi- Figure6showsthedistributionsofenvironmentaldensitiesat tiesaroundred,lowSFRgalaxiesinfilament-typesuperclusters smoothinglengths1,2,4,and8h−1Mpcinfilamentandspider- have higher values than in spider-type superclusters. Environ- type superclusters. At all smoothing lengths in these distribu- mentaldensitiesaroundred,highSFRgalaxiesinspider-typesu- tionspoorgroupswithN ≤9dominateatlowdensities;higher perclustersareclosetothoseforbluegalaxies;infilament-type gal valuesofdensitiescorrespondtorichergroups.Figure6shows superclusters the densities around them have somewhat higher a small deficit of intermediate-value densities in filament-type values.Infilament-typesuperclusterssomeofthesegalaxiesare Articlenumber,page5of14 A&Aproofs:manuscriptno.AA23111 ters of spider morphology, SCL 019 and SCl 099. The super- red, low SFR, F .25 blue, high SFR clustersSCl027andSCl019aretherichestsystemsintheSloan red, high SFR GreatWall(Einastoetal.2011b).ThesuperclustersSCl099(the red, low SFR, S blue, high SFR Corona Borealis supercluster)and SCl 001 belong to the dom- 0.20 red, high SFR inant supercluster plane (Einastoetal. 1997, 2011a). Figure 8 shows galaxy populations in these superclusters, and Table 2 theresultsoftheKStest, wherewe comparegalaxycontentof .15 filament-typesystemsandspider-typesystems. d Thegalaxypopulationsintheindividualrichestsystemsare alldifferent.Comparisonofthegalaxypopulationsoftherichest 0.10 filament-typesuperclustersandspider-typesuperclustersshows thatthedistributionsofalltheirgalaxypropertiesconsideredin thispaperare differentatveryhighsignificancelevel,the frac- .05 tionsof red, low SFR galaxiesin the richest filament-typesystems are higher than those in the richest spider-type systems. 0.0 Fortherichestfilament-typesystemsTable2showsthatalltheir 5 10 15 20 25 galaxypropertiesexceptstellarmassesaredifferentatveryhigh D8 significancelevel,thefractionofredgalaxiesintheSCl 001is Fig. 7. Distributions of environmental density at smoothing length higher than in SCl 027, and the fraction of galaxies with high 8 h−1Mpc around red, low SFR galaxies (red lines), blue, high SFR SFR islower. Forthe richestspider-typesuperclustersonlythe galaxies(bluelines),andred,highSFRgalaxies(greylines)insuper- stellar masses of galaxies in them are different at statistically clustersoffilament(solidlines)andspider(dashedlines)morphology. highsignificancelevel,galaxiesinSCl099havinghigherstellar massesthaninthoseSCl019. locatedinaratherhigh-densityenvironment.Alldifferencesare statisticallyhighlysignificant. 4 6 SCl027 SCl027 Our sample contain several very rich superclusters. We SCl001 SCl001 SCl019 SCl019 analyse their galaxy populations separately (Sect. 3.3). To see 5 SCl099 3 SCl099 whether our overallresults are affected by their dominancewe 4 repeatedallcalculationsexcludingtherichestsystemsfromthe d 3 d 2 sample.Allourresultsremainedthesame,thereforeneitherthe 2 superclustersfromtheSloanGreatWall,norotherveryrichsu- 1 perclustersdonotdominateinourresults. 1 0 0 0.2 0.4 0.6 0.8 1.0 0.0 0.2 0.4 0.6 0.8 1.0 3.2.Superclustersofdifferentshape g − r p_ l SCl027 0.75 SCl027 Superclusterscan be divided into more and less elongatedsys- 1.2 SCl001 SCl001 SCl019 SCl019 temsaccordingtothevalueoftheirshapeparameterK /K .The 1.0 SCl099 SCl099 1 2 smaller the shape parameter,the moreelongateda supercluster 0.8 0.5 is.SuperclusterswithK /K <0.5(moreelongatedsystems)are d d 1 2 0.6 calledfilamenttype,andthosewithK /K ≥0.5belongtopan- 1 2 0.4 0.25 cake type being less elongated systems (Einastoetal. 2011a). Costa-Duarteetal.(2013)analysedstellarpopulationsofgalax- 0.2 iesinsuperclustersofdifferentshape,usingshapeparameterto 0.0 0.0 characterisetheoverallmorphologyofsuperclusters.Similarly, 9.5 10.0 10.5 11.0 11.5 12.0 −2.0 −1.0 0.0 1.0 M_star SFR we use the shape parameter to divide superclusters of filament andspidertypesintosetsofmoreelongatedandlesselongated Fig. 8. The same as in Fig. 3 for the richest superclusters: filaments SCl001andSCl027(reddashedandsolidlines),andspidersSCl019 systemsandcomparegalaxypopulationsinthem.Theresultsare andSCl099(bluesolidanddashedlines). presentedwiththeKStestinTable2.Forvolume-limitedsam- plesgalaxypopulationsinmoreelongatedandlesselongatedsu- perclustersof filament morphologyare statistically similar. KS test shows that galaxy types and SFRs in more elongated and 3.4.Richandpoorgroupsinsuperclusters less elongatedsuperclustersof spider type are differentat very high significance level. Costa-Duarteetal. (2013) did not find Mostgalaxiesare locatedingroupsofvariousrichness.There- differences in galaxy populations in superclusters of different fore, as a next step we compared the galaxy content of groups shape,andwefoundthisforspider-typesystemsonly.Weanal- of different richness in filament- and spider-type superclusters ysed quite richsystems only,divingthem atfirst by theirinner andinthe field.We dividedgroupsof galaxiesin superclusters morphology.Thismayleadtothedifferencesinourresults. andinthefieldaccordingtotheirrichnessasverypoorsystems withN ≤3,poorgroupswiththenumberofmembergalaxies gal 4 ≤ N ≤ 11,andrichgroupswithN ≥ 12.Thecomparison 3.3.Therichestsuperclusters gal gal ofgalaxypropertiesinthreerichnessclassesaregiveninFig.9. Next we comparedgalaxypopulationsin the richestindividual ForclaritywepresentinFig.9theresultsforgroupsfromsuper- superclusters of both morphologicaltypes, the superclusters of clustersonly.TableC.4presentsthevaluesofquantilesofgalaxy filamentmorphology,SCl 001and SCl 027,and the superclus- properties. Articlenumber,page6of14 M.Einastoetal.:Sclgal Table2.TheresultsoftheKStest(the p -values):comparisonofthe 4 KS > 11, F > 11, F galaxypropertiesinfilament-andspider-typesuperclustersofdifferent 5 4 − 11 4 − 11 1 − 3 1 − 3 overallshapeandrichness. 4 >4 −11 1, 1S 3 >4 −11 1, 1S 1 − 3 1 − 3 (1) (2) (3) (4) (5) 3 d d 2 Moreelongatedandlesselongatedsuperclusters 2 Filaments Spiders 1 flux-lim vol-lim flux-lim vol-lim 1 p p p p KS KS KS KS 0 0 g−r 0.515 0.735 0.331 0.107 0.2 0.4 0.6 0.8 1.0 0.0 0.2 0.4 0.6 0.8 1.0 pl 0.099 0.535 0.003 0.011 1.4 g − r 1.0 p _l logM <1e−5 0.153 0.524 0.350 > 11, F > 11, F s 1.2 41 −− 131 41 −− 131 SFR 0.242 0.221 0.001 0.002 1.0 >41 −−11 13, 1S 0.75 >41 −−11 13, 1S Therichestsuperclusters 0.8 d d0.5 Filaments Spiders 0.6 SCl001,SCl027 SCl019,SCl099 0.4 0.25 flux-lim vol-lim flux-lim vol-lim 0.2 p p p p KS KS KS KS 0.0 0.0 g−r <1e−5 <1e−5 0.824 0.804 9.5 10.0 10.5 11.0 11.5 −2.0 −1.0 0.0 1.0 p <1e−5 <1e−5 0.001 0.127 M_star SFR l logMs <1e−5 0.063 0.012 <1e−5 Fig.9. ThesameasinFig.3forgroupsofdifferentrichnessinsuper- SFR 0.001 0.003 0.003 0.079 clustersoffilamentandspidermorphology (redandbluelines).Solid D <1e−5 <1e−5 <1e−5 <1e−5 lines show distributions for groups with at least 12 member galaxies. 8 Dashedlinescorrespondtodistributionsforgroupswith4≤N ≤11. gal DottedlinestosinglegalaxiesandgroupswithN ≤3. gal Notes.Columnsareasfollows:1:Galaxyproperties.g−r-colourin- dex, pl-probabilityofbeingalatetype,logMs-logstellarmass,SFR Table3.TheresultsoftheKStest(the pKS-values):galaxyproperties - log SFR, D8 - environmental density at 8 h−1Mpc scale smoothing in groups of different richness in superclusters of filament and spider scale;2–5:thepKS-valueofthetest. morphology. (1) (2) (3) (4) Figure 9 shows that the richer the group, the larger is the Property N <4 4≤N ≤11 N ≥12 gal gal gal fractionof red, early-type,low SFR, high stellar mass galaxies p p p KS KS KS init. We foundasimilartrendforgroupsinlow-densityglobal g−r 0.359 9e−05 0.122 environments. The KS test shows that differences between all p <1e−5 <1e−5 <1e−5 l galaxyparametersfrompoorerandrichergroupsarestatistically logM 0.006 0.017 0.014 s highlysignificant. SFR 3e-04 0.022 0.388 Figure 9 shows that colourdistributionsof galaxiesin very poor groups with N ≤ 3 are very similar in superclusters of gal different type. The KS test shows that the differences are not Notes.Columnsareasfollows:1:Galaxypropertiesarethesameasin statistically significant (Table 3). Galaxies in very poor groups Table2.2:thepKS-valuesofthetestforsinglegalaxiesandgroupswith insuperclustersoffilament-typehavehigherstellarmassesthan 2-3membergalaxiesinsuperclustersoffilamentandspidermorphol- ogy.3:thesameforgroupswith4-11member galaxies.4:thesame galaxiesinsuperclustersofspider-type,andthefractionofhigh forgroupswithatleast12membergalaxies. SFR galaxies among them is smaller. For richer groups Fig. 9 showsthatgroupsofthesamerichnesshostgalaxieswithhigher stellarmasses,andtheyhavealargerfractionofearly-typeand phology.Theysuggestedthatrichgroupsinsuperclustersofspi- redgalaxies,anda higherfractionof lowSFR galaxies,ifthey der morphologymay be dynamicallyyoungerthan rich groups arelocatedinsuperclustersoffilamentmorphology.Forcolours in superclusters of filament morphology.Next we compare the and SFRs the KS test says that the differences between groups peculiarvelocitiesof the main galaxiesof groupsin superclus- with less and more than 12 galaxiesare not statistically signif- ters and in the field to obtain an estimate of the group’s dy- icant. The stellar masses and types of galaxies are also signifi- namicalstate, and to understandwhether the differencesin the cantlydifferentinthecaseoftheserichnessclasses.Inthefield dynamical state of groups may be related to the differences in groups the fraction of red, low SFR galaxies is lower than in theirgalaxycontent.Inthesecalculationswedidnotwanttouse groupsof the same richnessin superclusters.Summarising,the dataofallgroupssinceforverypoorgroupscalculationsofthe galaxycontentofgroupsofthesamerichnessissomewhatdif- peculiar velocities of their main galaxies are not reliable. Re- ferentinsuperclustersoffilamentandspidermorphology. centlyRibeiroetal.(2013)usedseveralmethodstoanalysethe structureanddynamicalstateofgalaxygroupsandshowedthat these methods give quite reliable results for groups with more 3.5.Thepeculiarvelocitiesofthemaingalaxiesofgroups thantenmembergalaxies(Figure2andTable1in Ribeiroetal. Einastoetal.(2012a)showedthatinsuperclustersofspidermor- 2013).We madecalculationswithseveralgrouprichnesslimits phologyrichgroupswithN ≥50haveagreaterprobabilityof and foundthat the results are similar, but for richer groupsthe gal havingsubstructureandhigherpeculiarvelocities|v | of their sample size is smaller and this decreases the statistical signifi- pec maingalaxiesthanrichgroupsinsuperclustersoffilamentmor- canceoftheresults.ThereforeweusedgroupswithN ≥12in gal Articlenumber,page7of14 A&Aproofs:manuscriptno.AA23111 ouranalysis.We showthedistributionsofthevaluesofthepe- 4. Discussionandconclusions culiarvelocitiesofthemaingalaxiesingroupsin superclusters We showedthatthefractionof red,early-type,low SFRgalax- andinthefieldinFig.10(leftpanel). ies in superclusters of filament morphology is higher than in Figure 10 shows that the distributions are clearly different. superclustersof spider morphology.In addition,the fractionof The KS test says that the differences of the peculiar velocities thesegalaxiesinsuperclustersishigherthanamonggalaxiesin ofthemaingalaxiesingroupswithatleast12membergalaxies low-densityglobalenvironments.Thereare relativelymorered insuperclustersoffilamentandspidermorphology,andbetween galaxies among low stellar mass galaxies in spider-type super- supercluster and field galaxygroupsare statistically significant clustersthaninfilament-typesuperclusters. atveryhighlevels(p-valuep<0.05).Thereisadeficitofgroups In superclusters of filament morphology groups of equal withsmallvaluesofthepeculiarvelocitiesoftheirmaingalax- richnesshostgalaxieswithhigherstellarmasses,andtheyhave iesingroupsfromsuperclustersoffilamentmorphology,andan alargerfractionofearlytypeandredgalaxies,andahigherfrac- excess in groupsfromsuperclustersof spider morphology,and tion of low SFR galaxiesin comparisonwith groupsin spider- in the field. Einastoetal. (2012b) showed for very rich groups type superclusters. In agreement with Lietzenetal. (2012), we with Ngal ≥ 50thatingroupswiththepeculiarvelocitiesofthe found that groups of equal richness have a larger fraction of maingalaxies|vpec| < 250kms−1 maingalaxiesarelocatednear early-type and red galaxies, and a higher fraction of low SFR the centre of the group. Higher peculiar velocities of the main galaxies,iftheyarelocatedinhigh-densitylarge-scaleenviron- galaxiessuggestthatthemaingalaxyislocatedfarfromthecen- ments (superclusters) rather than in the field. In superclusters tre,a signof adynamicallyyounggroup.Figure10showsthat theyalsohostgalaxieswithhigherstellarmassesthangroupsin the peculiar velocities of the main galaxies in groupsin super- the field. Luparelloetal. (2013) also found that galaxy groups clustersoffilamentmorphologyarehigherthanthoseingroups in superstructures (Luparelloetal. 2011) have higher stellar from superclusters of spider morphology, suggesting that they masses, highervaluesofthe peculiarvelocities,andhaveolder aredynamicallyyounger.Intherichestgroupsweseetheoppo- galaxypopulationsthangroupsoutsideofsuperstructures. site: here the peculiarvelocitiesof the main galaxiesin groups About10%ofallgalaxiesinbothtypesofsuperclustersare from spider-type superclusters are higher than those in groups red, high SFR galaxies. These galaxies are mostly late type, of filament-type superclusters, as also shown in Einastoetal. their stellar masses are similar to stellar masses of red, low (2012a).Interestingly,wefoundthatgroupsofthesamerichness SFRgalaxies,andhigherthanthoseofbluegalaxies.Inspider- containalargerfractionofred,passivegalaxiesinsuperclusters typesuperclusterstheirstellarmasseshavehighervaluesthanin offilamentmorphologythaninsuperclustersofspidermorphol- filament-typesuperclusters.Earlierstudieshaveshownthatmas- ogy,andthistrendissimilarforgroupsofdifferentrichness,but sive galaxiesare red, independentof their morphologicaltypes thevaluesofthepeculiarvelocitiesdependonrichness. (Bamfordetal.2009;Mastersetal.2010;Einastoetal.2011b). We found that red, high SFR galaxies can usually be found at We also studiedthe relationbetweenthepeculiarvelocities lowandintermediatedensitiesinbothtypeofsuperclusters,but ofgroupmaingalaxies,andenvironmentaldensityinsuperclus- someofthemare also locatedatregionsof quitehighenviron- tersaroundthem,forseveralsmoothinglengths.Sincetheresults were similar, we present them for smoothinglength 8 h−1Mpc mental density. Red, high SFR galaxies typically lie at intermediate densities in small groups in superclusters (Wolfetal. only (Fig. 10, right panel). This figure shows a possible weak 2005; Einastoetal. 2008; Skibbaetal. 2009), but they can be correlationbetweenthepeculiarvelocitiesofthemaingalaxies alsofoundinrichclusters,andamongthemaingalaxiesofclus- and environmental density for filament-type superclusters, but ters (Einastoetal. 2011b), in agreement with our present find- not for spider-type superclusters. This was confirmed by Pear- ings.Thismeansthatprocesseswhichchangethecoloursoflate- son’scorrelationtestwhichshowedforfilament-typesuperclus- typegalaxiestoredwhilekeepingthehighSFRmustoccurboth ters that the correlation coeficient r = 0.19 with p = 0.06. inhigh-andintermediate-densityregions,andaremoreeffective For spider-typesuperclustersthis test foundthat r = 0.01with on high stellar mass galaxies. We plan to study their location p=0.93. ingroupsandclustersofindividualsuperclusterstounderstand theirdistributionandpropertiesbetter. Einastoetal. (2008, 2011b) determineda large variation in 0.003 F 1250 F the distributions of different galaxy populations in individual S S Field richsuperclusters.Wefoundinthepresentstudyalargediversity 1000 0.002 m/s) inthepropertiesofgalaxypopulationsoftherichestsuperclus- d0.001 v_pec (k 570500 toefrsgainlaoxuyrpsoapmuplaleti.oEnxspinlaisnuipnegrclalurgsteervsariisaatiocnhainlletnhgeedfisotrrigbaultaioxny formationmodels. 250 Costa-Duarteetal.(2013)showedthatthereisnodifference 0.0 0 betweenstellarpopulationsofgalaxiesinsuperclustersclassified 0 250 500 750 1000 1250 1500 5 10 15 20 by their overall shape as filaments and pancakes. In our study v_pec (km/s) D8 we foundthat when we divided superclusters of different mor- Fig. 10. Left panel: the peculiar velocities of the main galaxies in phologyby their shape parameterinto moreelongatedand less groups with at least 12 member galaxies in superclusters of filament elongatedpopulationsthenthedifferencesingalaxypopulation andspidermorphology(redandbluelines),andinthefield(greyline). betweenthemaresmall. Rightpanel:thepeculiarvelocitiesofthemaingalaxiesingroupswith Superclusters obtained their morphology and group and atleast12membergalaxiesinsuperclustersoffilamentandspidermor- galaxy populations during the formation and evolution of the phology(redandbluedots)vs.environmentaldensityinsuperclusters atsmoothinglength8h−1Mpc. cosmic web.In the Λ Cold Dark Matter (ΛCDM) concordance cosmologicalmodelthestructuresformingthecosmicwebgrow by hierarchical clustering driven by gravity (see Loeb 2002, Articlenumber,page8of14 M.Einastoetal.:Sclgal 2008, and referencestherein).The present-daydynamicalstate stripping of cold gas by the hot gas of the diffuse intra-cluster of clusters of galaxies depends on their formation history. We or intra-group medium (Gunn&Gott 1972), and strangulation analysedthedynamicalstateofgalaxygroupsusingthepeculiar orremovalofgalactichalogas(Larsonetal.1980).Thesepro- velocityoftheirmaingalaxiesasanindicatorofthedynamical cesses are effective both in galaxy groups and during mergers state,andfoundthatthevelocitiesinfilament-typesuperclusters of groups into clusters (pre- and post-processing of galaxies, are higher than those in spider-type superclusters. In this anal- Berrieretal.2009;Vijayaraghavan&Ricker2013). ysiswe usedgroupswith N ≥ 12.In contrast,forthe richest Cen (2011) used hydrodynamicalsimulations to show that gal clusters with N ≥ 50 Einastoetal. (2012a) found that these for galaxies at z = 0 star formation is efficient in low-density gal velocitiesarehigherinsuperclustersofspidermorphology. regions while it is substantially suppressed in cluster environ- Krauseetal. (2013) recently analysed the distribution and ments.Duringhierarchicalstructureformation,gasisheatedin dynamicalstateofgalaxygroupsintheUrsaMajorSupercluster high-densityregions(groups,clusters,andsuperclusters),andan (in our catalogue SCl 211 of filament morphology) and found increasinglylargerfractionofthegashasenteredaphasewhich that groups with Gaussian velocity distribution of their mem- istoohottofeedtheresidinggalaxies.Asaresult,thecoldgas ber galaxies are located in the denser regions of the super- supplytogalaxiesintheseregionsissuppressed.Theneteffect cluster. They suggested that relaxed galaxy groups in the su- isthatstar formationgraduallyshiftsfromthe largerhalosthat percluster have formed and evolved earlier and faster around populateoverdenseregionstolowerdensityenvironments.Thus, high-densitypeaks, while nonrelaxedsystems may be growing a lack of coldgas dueto gravitationalheatingin dense regions moreslowlyontheperipheriesoflowerdensitypeaks.Interest- may provide a physical explanation of cosmic downsizing and ingly, we foundin this study a weak correlationbetween envi- oneofitsmanifestationsisobservedasthecolour-densityrela- ronmentaldensityandthepeculiarvelocitiesofthemaingalax- tion. iesingroupsinfilament-typesuperclusters,sothatgroupswith Summarising,ourresultsareasfollows. higher values of the peculiar velocities of their main galaxies are located in higher density environments, this is opposite to 1) Thefractionofred,early-type,lowSFRgalaxiesishigherin theKrauseetal.(2013)result.Theystudiedonerichsuperclus- superclustersoffilament-typethaninsuperclustersofspider- ter. We showedthatthe propertiesof individualrich superclus- type, higher in superclusters than among galaxies in low- ters vary strongly.This may be the reason for different results. density globalenvironment,and higher in all environments Einastoetal. (2011b) found in the study of the richest super- inrichgroupsthaninpoorgroups. clustersintheSloanGreatWall, SCl027andSCl019,thatthe 2) Groups of equal richness host galaxies with higher stellar peculiarvelocitiesofthemaingalaxiesingroupsdependonthe masses,andtheyhavealargerfractionofearly-typeandred morphology of the main galaxies, and on their location in the galaxies, and a higher fraction of low SFR galaxies if they supercluster. arelocatedinsuperclustersoffilamentmorphology. Einastoetal. (2012a) assumed that superclusters of spider 3) Inspider-typesuperclustersthered,highSFRgalaxieshave morphologyhavericherinnerstructurethansuperclustersoffil- higherstellarmassesandlowervaluesofenvironmentalden- ament morphology with a large number of filaments between sitiesaroundthemthaninfilament-typesuperclusters. clustersinthemsomergersofclustersmayoccurmoreoftenin 4) Thepeculiarvelocitiesofthemaingalaxiesingroupsinsu- thesesuperclusters.Thereforeclustersinspider-typesuperclus- perclustersoffilamentmorphologyarehigherthaningroups terscouldbedynamicallyyounger.Thisagreeswiththeresults in superclusters of spider morphology.In filament-type su- of their galaxy populations,spider-type superclusters hosting a perclusters groups with higher peculiar velocities of their largerfractionofblue,starforminggalaxies,butcontradictsthe main galaxies are located in higher density environments calculationsofthepeculiarvelocitiesoftheirmaingalaxies.This thanthosewithlowpeculiarvelocities. is one of the open questions for future studies of superclusters 5) Therearesignificantdifferencesbetweengalaxypopulations andgalaxyclustersinthem. oftheindividualrichestsuperclusters. Einastoetal. (2005) showed by numerical simulations that Theseresultssuggestthatbothlocal(group)andglobal(su- inlow-densityglobalenvironmentonlypoorsystemsform,these percluster) environments,and inner structure and detailed den- systemsgrowveryslowly.Inhigh-densityglobalenvironments, sity distribution in superclustersare importantfactors affecting thedynamicalevolutionisrapidandstartsearlier,consistingofa theevolutionofgalaxiesandgalaxygroupsinthem.Ourstudy continuaoftransitionsofdarkmatterparticlestobuildingblocks indicatedseveralopenquestionsthatneedfuturestudies.Itisnot ofgalaxies,groups,andclusters.Darkmatterhalosinvoidsare clearhowthe processesthatshapethe propertiesofgalaxiesin foundtobelessmassive,lessluminous,andtheirgrowthofmass differentenvironmentsarerelatedtothesuperclusterscaleden- issuppressedandstopsatearlierepochsthaninhigh-densityre- sityfield,andhowthesuperclustermorphologyisrelatedtothe gions.DuringthestructureformationintheUniverse,halosizes properties of galaxies and groups in them. We plan to develop in the supercluster core regionsincrease, while in void regions furtherthemethodstoquantifyinnerstructureofsuperclusters, halosizesremainunchanged(Tempeletal.2009).Thus,during inordertounderstandbettertheroleofsuperclusterenvironment theevolutionofstructuretheoveralldensityinsuperclustersin- intheformationandevolutionofgalaxiesandgalaxygroupsin creases, whichenhancestheevolutionofthe small-scaleproto- them.We alsoplantostudytheinnerstructureofsuperclusters halos in them (Suhhonenkoetal. 2011). This may lead to the differences in the properties of galaxy groups and galaxies in usinggalacticfilaments(Tempeletal.2013). theminsuperclustersandinthefield. A number of processes that transform galaxies in high- Acknowledgments density environments have been proposed, either observation- ally or in simulations. These include galaxy-galaxy merg- We thank the referee for invaluablecommentsand suggestions ers (Barnes&Hernquist 1992), galaxy harassment (Richstone which helped to improve the paper. We thank Enn Saar for 1976; Mooreetal. 1996), tidal stripping by the host group or very fruitful collaboration on studies of supercluster morphol- cluster’s gravitational potential (Gnedin 2003), ram pressure ogy. We are pleased to thank the SDSS Team for the publicly Articlenumber,page9of14 A&Aproofs:manuscriptno.AA23111 available data releases. Funding for the Sloan Digital Sky Sur- Einasto,M.,Tago,E.,Jaaniste,J.,Einasto,J.,&Andernach,H.1997,A&AS, vey (SDSS) and SDSS-II has been provided by the Alfred P. 123,119 Sloan Foundation, the Participating Institutions, the National Einasto,M.,Vennik,J.,Nurmi,P.,etal.2012b,A&A,540,A123 Science Foundation, the U.S. Department of Energy, the Na- Gnedin,O.Y.2003,ApJ,582,141 tionalAeronauticsandSpaceAdministration,theJapaneseMon- Gunn,J.E.&Gott,III,J.R.1972,ApJ,176,1 bukagakusho,and the Max Planck Society,and the HigherEd- Hamilton,A.J.S.1988,ApJL,331,L59 ucation Funding Council for England. The SDSS Web site is Huchra,J.P.&Geller,M.J.1982,ApJ,257,423 http://www.sdss.org/.TheSDSSismanagedbytheAstro- Huertas-Company, M., Aguerri, J. A. L., Bernardi, M., Mei, S., & Sánchez physicalResearchConsortium(ARC)fortheParticipatingInsti- Almeida,J.2011,A&A,525,A157 tutions.TheParticipatingInstitutionsaretheAmericanMuseum Ihaka,R.&Gentleman,R.1996,JournalofComputationalandGraphicalStatis- of NaturalHistory, AstrophysicalInstitute Potsdam, University tics,5,299 ofBasel,UniversityofCambridge,Case WesternReserveUni- Jõeveer,M.,Einasto,J.,&Tago,E.1978,MNRAS,185,357 versity,TheUniversityofChicago,DrexelUniversity,Fermilab, Kauffmann,G.,Heckman,T.M.,White,S.D.M.,etal.2003,MNRAS,341,33 theInstituteforAdvancedStudy,theJapanParticipationGroup, Kirshner,R.P.,Oemler,Jr.,A.,Schechter,P.L.,&Shectman,S.A.1981,ApJL, The Johns Hopkins University, the Joint Institute for Nuclear 248,L57 Astrophysics, the Kavli Institute for Particle Astrophysics and Komatsu,E.,Smith,K.M.,Dunkley,J.,etal.2011,ApJS,192,18 Cosmology,the KoreanScientistGroup,the Chinese Academy Krause,M.O.,Ribeiro,A.L.B.,&Lopes,P.A.A.2013,A&A,551,A143 of Sciences (LAMOST), Los Alamos National Laboratory,the Larson,R.B.,Tinsley,B.M.,&Caldwell,C.N.1980,ApJ,237,692 Max-Planck-Institutefor Astronomy(MPIA), the Max-Planck- Lietzen,H.,Tempel,E.,Heinämäki,P.,etal.2012,A&A,545,A104 InstituteforAstrophysics(MPA),NewMexicoStateUniversity, Liivamägi,L.J.,Tempel,E.,&Saar,E.2012,A&A,539,A80 Ohio State University, University of Pittsburgh, University of Loeb,A.2002,Phys.Rev.D,65,047301 Portsmouth, Princeton University, the United States Naval Ob- Loeb,A.2008,ArXive-print:0804.2258 servatory,andtheUniversityofWashington. Luparello,H.,Lares,M.,Lambas,D.G.,&Padilla,N.2011,MNRAS,415,964 The present study was supported by the Estonian Science Luparello,H.E.,Lares,M.,Yaryura,C.Y.,etal.2013,MNRAS,432,1367 FoundationgrantNo.8005,grants9428,MJD272,PUT246,by Martínez,V.J.&Saar,E.2002,StatisticsoftheGalaxyDistribution(Chapman theEstonianMinistryforEducationandScienceresearchproject &Hall/CRC,BocaRaton) SF0060067s08,andbytheEuropeanStructuralFundsgrantfor Masters,K.L.,Mosleh,M.,Romer,A.K.,etal.2010,MNRAS,405,783 theCentreofExcellence"DarkMatterin(Astro)particlePhysics Mo,H.J.,Einasto,M.,Xia,X.Y.,&Deng,Z.G.1992,MNRAS,255,382 and Cosmology" TK120. This work has also been supported Moore,B.,Katz,N.,Lake,G.,Dressler,A.,&Oemler,A.1996,Nature,379, by ICRAnet through a professorshipfor Jaan Einasto. H. 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SDSS superclusters: morphology and galaxy content

Similar SDSS superclusters: morphology and galaxy content