Radio emission from the A3571 cluster complex: the final stage of a cluster merger?

17 Pages·0.34 MB·English

by  T. Venturi

1
Abstract. In this paper we report and discuss the results of
a radio survey in the A3571 cluster complex, a structure lo-
cated in the Shapley Concentration core, and formed by the
threeclustersA3571,A3572andA3575.Thesurveywascar-
riedoutsimultaneouslyat22cmand13cmwiththeAustralia
Telescope CompactArray,and led to the detection of 124 ra-
dio sources at 22 cm. The radio source counts in this region
are in agreement with the background counts. Among the 36
radiosourceswithopticalcounterpart,sixhavemeasuredred-
shift which places them at the distance of the A3571 cluster
2 complex,andnineradiosourceshaveopticalcounterpartsmost
0
likelymembersofthisclustercomplex.Allradiogalaxiesemit
0
atlowpowerlevel,i.e.logP (WHz−1)≤22.6.Anumber
2 22cm
ofthemarelikelytobestarburstgalaxies.Theradioluminos-
n
ityfunctionofearlytypegalaxiesisinagreementwiththatde-
a
J rivedbyLedlow&Owen(1996)if werestrictouranalysisto
theA3571cluster.Onthebasisofthemultiwavelengthproper-
1
3 tiesoftheA3571clustercomplex,weproposethatitisavery
advancedmerger,andexplaintheradiopropertiesderivedfrom

1 ourstudyinthelightofthishypothesis.
v
2
Key words: Radio continuum: galaxies - Clusters: general -
3
5 Galaxies: clusters: individual: A3571 galaxies: clusters: indi-
1 vidual:A3572galaxies:clusters:individual:A3575
0
2
0
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:
v
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A&Amanuscriptno. ASTRONOMY
(willbeinsertedbyhandlater)
AND
Yourthesauruscodesare:
ASTROPHYSICS
missing;youhavenotinsertedthem
Radio emission from the A3571 cluster complex: the final stage of a
cluster merger?
T.Venturi1,S.Bardelli2,M.Zagaria1,3,I.Prandoni1,3,andR.Morganti4
1 IstitutodiRadioastronomia,CNR,ViaGobetti101,I–40129,Bologna,Italy
2 OsservatorioAstronomico,ViaRanzani1,I–40126Bologna,Italy
3 DipartimentodiAstronomia,Universita`diBologna,ViaRanzani1,I–40126,Bologna,Italy
4 NFRA,Postbus2,A7990Dwingeloo,TheNetherlands
Received/Accepted
1. Introduction We surveyed the A3558 and A3528 cluster regions at 22
cm with the Australia Telescope Compact Array (ATCA) to
Mergingbetweenclustersisthoughttoberesponsibleforsig-
thelimitingfluxdensityof∼0.8mJy(Venturietal.2000and
nificantchangesinthephysicsoftheintraclustermediumand
2001). It was found that the A3558 complex is characterised
intheemissionpropertiesofthegalaxypopulation,asaconse-
bya significantlack ofradiosourceswith respectto the clus-
quenceoftheenormousenergybudgetinvolved(∼1060ergs).
ter sample of Ledlow & Owen (1996), suggesting the possi-
The effects of this dynamical process on the hot gas are bility that cluster–cluster collisions would “swith off”the ex-
clearandwelldocumented(Sarazin2000),aswellasthecon- isting radio sources, or inhibit the birth of new ones. On the
nection between cluster merging and peculiar radio sources contrary,thenumberofradiosourcesfoundintheA3528com-
such as relics and halos (Feretti & Giovannini 1996). In par- plexisstatisticallyconsistentwiththeoneofthecontrolsam-
ticular,theseextendedradiosourcesarefoundtobeassociated ple.Thesetwodifferentbehaviourscanbepossiblyexplained
withclusterswithsomedegreeofdisturbance,suggestingthat intermsofmergingage:theA3558complexisatanadvanced
merging is responsible for the reacceleration of the relativis- stage (possibly after the first core-core encounter, Bardelli et
tic electrons (Feretti & Giovannini,2001; Ensslin& Bru¨ggen, al.1998),whiletheA3528complexisanearlymerging,where
2001;Brunettietal.2001;Buote2001).Ontheotherhanditis clustersjuststartedtointeract(seeforexamplethesimulations
notyetunderstoodwhether cluster–clustercollision is able to byRicker&Sarazin2001).
modifytheradioemissionpropertiesofasinglegalaxyand/or
In this paper we present the radio–optical analysis of the
affectthestatisticsoftheradiosourcepopulation.
third groupof clustersin the centralpartof the ShapleyCon-
In order to address this issue, we are carryingon a multi- centration, i.e. the A3571–A3572–A3575chain. In Section 2
wavelengthstudyofthecentralpartoftheShapleyConcentra- we overviewopticalandX–raypropertiesoftheA3571com-
tion,whereanunusuallyhighnumberofclustersaremerging. plex;inSection3wereportontheradioobservations;theradio
This situation originated from the high local density, that in- source sample and the optical identifications are described in
ducedpeculiarvelocitiesoftheorderof∼1000kms−1. Section4;theradiopropertiesoftheA3571complexarepre-
Zuccaetal.(1993)performedapercolationanalysisofthe sented in Section 5, and the radio and optical number counts
Abell-ACOclustersinordertofindsuperclustersandtostudy arederivedinSection6.Discussionandconclusionsaregiven
the grouping characteristics as a function of the overdensity inSection7.
withrespecttothemeandensityofclusters.Inparticular,they We will use H = 100 km s−1Mpc−1 and q = 0, which
o o
found that at the highest density contrasts (>40), the central leadstoalinearscale1arcsec=0.55kpcattheaverageredshift
partoftheShapleyConcentrationisfragmentedinthreemain oftheclustercomplex(z=0.039).
structures(“clustercomplexes”or“groupsofclusters”).Oneis
dominated by the cluster A3558 and could be considered the
coreofthesupercluster;asecondisformedbyA3528,A3530
2. TheA3571ComplexintheShapleyConcentration
andA3532.Bothcomplexespresentveryclearsignsofongo-
ing merging (Hanami et al. 1999; Bardelli et al. 1996; Ettori ThechainformedbythethreeclustersA3571–A3572–A3575
etal.1997;Kull&Bo¨hringer1999;Schindler1996).Thethird lies∼5◦eastofthegeometricalcentreoftheShapleyConcen-
group of clusters in this region is dominated by A3571, and tration, defined by the A3558 complex. In Fig. 1, we plotted
includesA3572andA3575. the galaxy isodensity contoursin this region,after smoothing
theopticalcounts(derivedfromtheCOSMOScatalogue)with
Sendoffprintrequeststo:VenturiT. aGaussianof6arcminofFWHM.Thesizeofthestructureis
Correspondenceto:[email protected] approximately150×70arcmin,correspondingto5.1×2.4h−1
VenturiT.etal.:TheA3571ClusterComplex 3
Mpc at 11550km s−1 (the averagevelocity of the three clus- Table1.PropertiesoftheclustersintheA3571chain.
ters).Thepresenceofa significantoverdensityattheposition
of A3571 is evident, with a tail extendingdown to the centre
ofA3572.ItisdifficulttoassessifA3572ispartofA3571,or Cluster RAJ2000 DECJ2000 B-M(R) vrec s v
h m s ◦ ′ kms−1 kms−1
ifitisanindependentstructure.Lessclearistheexistenceofa
galaxyexcessatthepositionofA3575.
A3571 134730 −3251 I(2) 11730a 1022a
A3572 134812 −3322 I-II(0) 12142b 1300b
100 A3575 135236 −3252 II(0) 11250c 572c
aQuintana&deSouza(1993)
bDrinkwateretal.(1999)
50 cQuintanaetal.(1997)
north-southdirection(Kemp&Meaburn1991),inthesamedi-
0 rectionofthebi-dimensionalgalaxydistribution.
As noted by Nevalainen et al. (2000and 2001),while the
galaxydistributionindicatessomedegreeofnon-relaxation,the
X–rayobservationsshowthatA3571isawellrelaxedcluster,
withthepresenceofacoolingflow.Thehotgastemperatureis
-50
7.6keV(Nevalainenetal.2001),consistentwiththegalaxyve-
locitydispersion.Nevalainenetal.(2001)determinedalsothe
totalmassusingthehydrostaticequilibriumofthehotgas,and
foundMtot ∼4.6×1014 h−1 M⊙. For comparison,the results
-100 ofthevirialmassofGirardietal.(1998)isM ∼9×1014h−1
100 50 0 -50 -100 tot
M .
⊙
Fig.1. Isocontours of the galaxy density to b = 19.5 in the
j
A3571 complex. The figure is centered at a = 13h 49m 10s, 2.2. A3572andA3575
d = −32◦ 31′ 47”.Dashedlinescorrespondto 1 Abellradius Littleisknownabouttheothertwoclustersinthecomplex.
circlesaroundclustercentres,giveninTable1.Thecountshave A3572 has a richness class R = 0 and is located south of
beensmoothedwithaGaussianof6arcminFWHM. A3571 in the plane of the sky (see Fig. 1). Drinkwater et al.
(1999)foundameanvelocityof<v>=12142kms−1,which
impliesanaverageredshift<z>=0.0405.
Table1summarizesthemostimportantfeaturesofthethree
A3575 has R = 0 and lies east of A3571. Quintana et al.
clusters:incolumns1,2and3wegiverespectivelynameand
(1997)found<v>=11250kms−1 (i.e.<z>= 0.0375)and
J2000coordinatesofthecentre(takenfromtheACOcatalogue,
s =572kms−1onthebasisofonly12velocities.
Abell,Corwin&Olowin1989);incolumn4theBautz-Morgan
No information is available in the literature on the X–
typeandrichnessclass;incolumns5and6theaveragereces-
ray properties of these two clusters. Visual inspection of the
sionvelocityandthevelocitydispersionrespectively.
ROSAT All Sky Surveyimagesdoes notshow any indication
ofX–rayemission.
2.1. A3571
The dominant member of the complex is the cluster A3571, 3. ObservationsandDataReduction
withrichnessclassR=2(Abell,Corwin&Olowin,1989)and
3.1. 22cmand13cmATCAObservations
Bautz-Morgan type I. The mean velocity is v=11730±127
kms−1 andthe velocitydispersionis1022+99 kms−1 (Quin- We imaged the A3571 complex with the Australia Telescope
−77
tana & de Souza, 1993). Quintana & de Souza (1993) sug- CompactArray(ATCA)at22cm (n =1.38GHz) and13cm
gestedthatthevelocitydistributionisasymmetricandthatthe (n =2.38GHz)simultaneously.Thewholeregionwascovered
bi-dimensionalgalaxydistributionpresentssomeindicationsof withsixdifferentpointings,whosecentresarelistedinTable2.
substructure. Theseparationbetweencontiguousfieldsis20arcmin.
A3571 is characterised by the presence of the large cD The observations were carried out in 1995 (December 22
galaxy MCG05−33−002, located at its centre. This galaxy, and23),usingthemosaicingfacilityoftheATCA.Toobtaina
withanextensionof0.1×0.3h−1Mpc,iselongatedalongthe good hourangle coverage,the six fields were observedin se-
4 VenturiT.etal.:TheA3571ClusterComplex
Table2.Detailsontheobservations. the ATCA observations. Multifrequency synthesis techniques
are implemented, and this allows proper gridding of the data
in orderto reducebandwidthsmearing effects. This is an im-
Field RA DEC rms rms
J2000 J2000 22cm 13cm portantfeature,giventhatwewanttoimagethefieldsaslarge
h m s ◦ ′ mJyb−1 mJyb−1
as possible. We reducedthe data and imaged each field sepa-
rately.Thesixcleaned22cmimageswerethenmosaiced(i.e.,
linearlycombined)usingtheMIRIADtaskLINMOS,inorder
#1 134730 −3251 0.12 0.12
#2 134911 −3251 0.11 0.11 toobtainauniformsensitivityoverthewholeregion.Thearea
#3 135052 −3251 0.11 0.12 coveredbyourmosaicis∼2.4deg2.Theimageanalysiswas
#4 135231 −3251 0.12 0.12 carriedoutwiththeAIPSpackage.
#5 134757 −3310 0.11 0.11 AsshowninFig.2,apointingseparationof20arcminal-
#6 134812 −3325 0.11 0.11 lowsagoodoverlapbetweenfieldsat22cm,wheretheprimary
beamsizeisFWHM∼33′,anditisbestsuitedtogetuniform
sensitivityoverthecentralregionoftheradiomosaic(Prandoni
etal.2000a).Ontheotherhand,theprimarybeamsizeat13cm
100 (FWHM∼22′)iscomparabletothedistancebetweenadjacent
fields,andtheverylittleoverlapdoesnotallowtocompensate
for the radial sensitivity loss due to the primarybeam attenu-
ation. The mosaic techniqueis noteffectiveat this frequency,
50 thereforeinthiscasewetreatedeachimageseparately.
The average rms noise values measured in the individual
fieldsatboth22cmand13cmarelistedinTable2;theaverage
rmsfluxdensitymeasuredoverthewholemosaiciss =0.13
mJyb−1.Atbothwavelengthsweassumedasourcedetection
0
flux limit S = 0.65 mJy b−1 (i.e. ∼5s ). Such limit translates
intoaradiopowerdetectionlimitlogP (WHZ−1)=21.02at
22
theaveragedistanceoftheA3571clustercomplex.
-50 Theinternaluncertaintyofthesourcefluxdensityandpo-
sition measures can be estimated following Prandoni et al.
(2000b), since our ATCA interferometric data are very simi-
lartothosepresentedintheirwork(samefrequencyandarray
configuration).
-100
100 50 0 -50 -100 For unresolved (pointlike) radio sources the uncertainty
D S, associated with the flux density dependson the flux den-
sity itself (S ),onthelocalsignal-to-noiseratio,definedas
Fig.2. Fields of the observations overlaid on the the galaxy peak
density (same as in Fig. 1). The radius of each circle is 30′. Speak/s ,andonthecalibrationresidualerrors,asfollows:
ThecentresofeachfieldaregiveninTable2. D S=s (S )/S =0.93 Speak −1 . (1)
peak peak (cid:18) s (cid:19)
Using thisequation,a radiosourcewith peakflux density
quence,fortwominuteseach.Thecycle(includingcalibration) S =0.65mJyb−1andsignal-to-noiseratioof5,hasD S =
peak
wasrepeatedfor2×12hours.Thearrayoperatedisthe 6.0C
0.12mJy.
configuration(fullATCAresolution),whichyieldsaresolution
The internal position error of the radio sources depends
of ∼ 11′′ × 5′′ at the declinationof the A3571 complex.The
again on the local signal-to-noise ratio, and on the synthe-
largestdetectablestructuresizeis∼3arcmin.
sized beam, accordingto the followingformulas(Prandoniet
We observed in continuum mode with a 128-MHz band-
al.2000b):
width,dividedin32 × 4MHzchannels,inordertoreducethe b S −1
bandwidth smearing effects at large distance from the point- s a ≃ m2in(cid:18) pseak(cid:19) , (2)
ingcentres.B1934−638wasusedasprimaryfluxdensitycal-
iSbrator=, w1it1h.6aJsys.umed flux densities S22cm = 14.9 Jy and s d ≃ bm2aj(cid:18)Spseak(cid:19)−1 , (3)
13cm
whereweassumedb =5′′ andb =11′′,theaverage
min maj
synthesizedbeamvaluesofthe22cmsurvey.Radialdeforma-
3.2. DataReductionandImageAnalysis
tions due to the cromatic aberrationare negligiblein our mo-
ThedatareductionwascarriedoutwiththepackageMIRIAD saic,sowedidnotcompensateforthiseffect.Weassumedfor
(Sault,Teuben&Wright,1995),whichisparticularsuitedfor all sources a conservative position uncertainty of 1′′, both in
VenturiT.etal.:TheA3571ClusterComplex 5
RAandinDEC,whichcorrespondstothevaluesfortheweak-
estsourcesinthesample,i.e.5s detections.
4. Results
4.1. TheSampleofRadioSources
Wedetectedatotalof124sourcesat22cmabove0.65mJyin
themosaicimage.Wepointoutthatduetothesmallerfieldof
viewofthe13cmobservations,andtopossiblespectralindex
effects, only a fraction of the sources detected at 22 cm was
revealedat this shorter wavelength.In particular at 13 cm we
detected36/124sources,i.e.29%.
ThesourcelistisreportedinTable3,wherewegivename
and J2000position (columns1, 2 and 3);integratedflux den-
sityat22cmcorrectedfortheprimarybeamattenuation(col-
umn4);integratedfluxdensityat13cmcorrectedforthepri-
marybeamattenuation(column5);spectralindexa 22forthose Fig.3.Distributionofthespectralindexa 22 forthosesources
13 13
sourcesdetectedatbothfrequencies(column6),to bereadin inthesampledetectedatbothwavelengths.
the sense S (cid:181) n −a ; radio morphology(column7). For those
sourcesundetectedat13cm,a⋆isreportedinTable3.
plate frame to the sky, however, introduces further uncertain-
By inspecting our 22 cm mosaic image, we classified the
ties,soweadoptedaconservativemeanpositionalerrorof1.5′′
radio morphology of the sources as follows: unresolved (un-
(Unewisseetal.1993).
res.),resolved/extended(res.)anddouble(D).Fortheextended
Duetoincompletenesseffectsatbothfaintandbrightmag-
sources in the sample we give the position of the radio peak,
nitudes(brightgalaxiescan be resolvedout) all radiosources
while for the two double systems we give the coordinates of
were overplotted on the Digitized Sky Survey (DSS) images
the barycentre. The majority of the radio sources, 110 out of
andscrutinizedbyeye,tomakesurethatnoidentificationwas
124 (∼89%), are unresolvedat the resolution of the final im-
missed.
age, 2 (∼2%) have a double structure and the remaining 12
Given the uncertainties in the radio and optical positions,
(∼9%)areextended.
weestimatedthereliabilityofouridentificationsusingthepa-
InFig.3weshowthedistributionofthespectralindexfor
rameterR,definedas:
thosesourcesdetectedatboth22cmand13cm.Wepointout
thatthe computationof the spectralindexwas doneusingthe D 2
total flux density as measured on the images, so the different R2= r−o
s 2+s 2
u−v coverageat the two wavelengthswas not taken into ac- g r
count.For extended/resolvedradio sources,this may havebi- where D is the positionaloffset between the radio and op-
r−o
assed our analysis towards spectra steeper than their intrinsic tical coordinates,s is theopticalpositionerrorand s isthe
g r
shape,giventhelackofshortspacingsat13cm.Thiseffectis uncertaintyintheradioposition.
particularlyevidentforthetwosourceswiththesteepestspec- Forpoint-likeradiosourcesandpoint-likeopticalcounter-
tra: they are both extended sources (see Table 3), and we be- parts, we considered reliable identifications all matches with
lieve that a fraction of their extended flux was missed at 13 R ≤ 3;fortheextendedradiosourcesand/orextendedoptical
cm.FromFig.3weconcludethatthesampleofradiosources galaxies,the value of R is less meaningfuland we trustedthe
includesbothcompactactivenucleiwithflatandinvertedspec- directeyeinspection.
trum,andradiosourceswithnormaltomoderatelysteepspec- Finally,weusedNED(NASAExtragalacticDatabase)to
trum. searchfortheredshiftinformationoftheopticalcounterparts,
and consideredas belongingto the Shapley Concentrationall
galaxieswithrecessionvelocitiesintherange10000< v (km
4.2. OpticalIdentifications r
s−1)<18000.
We searched for optical counterpartsof the radio sources de-
tectedinour22cmsurveyusingtwodifferentcatalogues:the We found 36 optical counterparts, ∼ 29% of the total, 6
COSMOS/UKSTSouthernSkyObjectCatalogue(Yentisetal., of whichwith knownredshiftandallbelongingto the A3571
1992), limited to b = 19.5, and the APM Catalogue (Auto- complex(∼ 17%of the 36 sourcesidentified).The list of the
j
matedPhotographicMeasuring),limited to b = 20(Maddox radio–optical identifications is given in Table 4, which is or-
j
etal.1990).Bothcataloguesaretheresultofautomaticscansof ganisedasfollows:column1=radioandopticalname(where
theUKSchimdtTelescope(UKST)platesandhaveaclaimed available);columns2and3=coordinates(J2000)oftheradio
positional accuracy of ∼0.25′′. The transformation from the sourceandoftheopticalcounterpart;column4=fluxdensity
6 VenturiT.etal.:TheA3571ClusterComplex
oftheradiosourceat22cmandtheb magnitudeofthecoun-
j
terpart;column5=fluxdensityat13cm;column6=spectral
indexa 22andopticalcatalogueusedtoretrievetheinformation
13
(A=APM,C=COSMOS);column7=monochromaticradio
powerat22cmfortheradiogalaxieswithknownredshiftand
absolute magnitudeB of the opticalcounterpart;column8 =
j
radiomorphologyandparameterR;column9=clusterwhere
theradiogalaxyislocatedandrecessionvelocity.
Inanumberofcasesthelargeopticalextentofthegalaxy
and/or the extent of the radio emission lead to R > 3. For
thesesourcesweconsideredtheidentificationasreliableifthe
optical counterpartfalls within the radio isophotes. A note to
Table4clarifiesthesecases.
Thelocationoftheradiosourcesoverlaidontheopticaliso-
densitiesoftheA3571complexisshowninFig.4.Wenotethat
the radio sources are distributed fairly uniformly over the re-
gioncoveredbyourobservations,regardlessoftheunderlying
optical density, which varies considerably going from A3571
to the otherclustersin the chain.FromTable 4 it isclear that
theShapleyradiogalaxies,i.e.galaxieswithmeasuredredshift,
arelocatedinA3571(4/6)andintheregionbetweenthecentre
ofA3571andA3575(2/6).
100
50
0
-50
-100
100 50 0 -50 -100
Fig.4.Locationoftheradiosourcesoverlaidontheopticaliso-
densities of the A3571 complex. Filled squares represent the
opticallyidentifiedradiogalaxieswithmeasuredredshift,filled
circlesthosewithoutredshiftinformationandcrossesstandfor
theradiosourceswithoutopticalcounterparts.
VenturiT.etal.:TheA3571ClusterComplex 7
Table3.Sourcelistandfluxdensityvalues.
Name RA DEC S S a 22 Morph.
J2000 J2000 22cm 13cm 13
h m s ◦ ′ ′′ mJy mJy
J1346−3259 134613.0 −325933 2.41 ⋆ unres.
J1346−3252 134613.7 −325228 3.90 ⋆ unres.
J1346−3231 134625.9 −323139 5.57 − unres.
J1346−3237 134634.3 −323708 1.89 ⋆ unres.
J1346−3235 134638.8 −323555 12.59 ⋆ unres.
J1346−3303 134639.4 −330344 1.04 ⋆ unres.
J1346−3254 134640.9 −325423 1.20 ⋆ unres.
J1346−3305 134647.6 −330503 4.45 ⋆ unres.
J1346−3320 134650.3 −332015 1.09 ⋆ unres.
J1346−3304 134650.4 −330459 4.20 ⋆ unres.
J1346−3248 134653.4 −324822 1.69 ⋆ unres.
J1346−3346 134659.0 −334616 4.47 − unres.
J1347−3311a 134702.7 −331151 0.89 ⋆ unres.
J1347−3332 134707.3 −333206 2.32 ⋆ res.
J1347−3339a 134708.1 −333945 5.52 − unres.
J1347−3306 134709.0 −330646 0.84 ⋆ unres.
J1347−3313 134709.4 −331351 1.35 ⋆ unres.
J1347−3334 134720.2 −333447 2.29 ⋆ unres.
J1347−3252♦ 134724.6 −325215 24.23 11.23 1.41 D
J1347−3325 134724.2 −332511 16.29 4.55 2.34 res.
J1347−3256 134725.3 −325610 1.34 ⋆ unres.
J1347−3324 134725.4 −332441 7.08 ⋆ res.
J1347−3229 134726.5 −322930 54.39 - unres.
J1347−3314 134726.8 −331433 1.04 ⋆ unres.
J1347−3251 134728.5 −325154 4.05 2.52 0.87 unres.
J1347−3310 134731.4 −331004 3.83 2.80 0.57 unres.
J1347−3241 134734.3 −324131 2.96 1.54 1.20 unres.
J1347−3323 134736.3 −332328 3.38 1.92 1.04 unres.
J1347−3339b 134737.3 −333927 7.13 7.76 −0.16 unres.
J1347−3311b 134742.4 −331143 15.60 9.15 0.98 unres.
J1347−3328 134748.7 −332840 4.12 1.90 1.42 unres.
J1347−3259 134753.1 −325901 1.08 ⋆ unres.
J1347−3236 134754.2 −323659 14.18 10.44 0.56 unres.
J1347−3301 134756.8 −330106 9.09 6.12 0.73 unres.
J1347−3330♣ 134757.5 −333002 5.06 3.79 0.53 unres.
J1347−3302 134759.5 −330203 0.98 ⋆ unres.
J1348−3311 134804.2 −331133 1.13 0.74 0.78 unres.
J1348−3315 134804.9 −331558 1.47 ⋆ unres.
J1348−3246 134808 −324615 192.08 102.54 1.15 D
J1348−3339 134810.5 −333931 2.25 ⋆ unres.
J1348−3323 134814.3 −332332 2.22 ⋆ unres.
J1348−3239 134815.3 −323931 1.04 ⋆ unres.
J1348−3255 134816.1 −325533 0.75 ⋆ unres.
J1348−3234 134824.9 −323435 4.06 ⋆ unres.
J1348−3249 134830.3 −324910 1.03 ⋆ unres.
J1348−3256 134832.3 −325633 1.82 ⋆ unres.
J1348−3318 134833.5 −331847 0.92 ⋆ unres.
J1348−3328 134835.1 −332818 0.69 ⋆ unres.
J1348−3310 134837.5 −331004 11.70 6.75 1.01 unres.
J1348−3258 134839.6 −325816 1.22 1.46 −0.33 unres.
8 VenturiT.etal.:TheA3571ClusterComplex
Table3.−continued
Name RA DEC S S a 22 Morph.
J2000 J2000 22cm 13cm 13
h m s ◦ ′ ′′ mJy mJy
J1348−3257 134846.3 −325737 6.42 4.04 0.85 unres.
J1348−3241 134846.5 −324141 4.35 3.37 0.47 res.
J1348−3303 134847.7 −330316 14.15 6.52 1.42 unres.
J1348−3305 134852.9 −330517 3.22 ⋆ unres.
J1348−3304 134855.6 −330459 3.74 ⋆ unres.
J1348−3250 134858.9 −325045 0.76 ⋆ unres.
J1348−3337 134859.8 −333755 2.68 ⋆ unres.
J1349−3326 134902.3 −332657 0.93 ⋆ unres.
J1349−3243 134907.8 −324336 3.00 ⋆ res.
J1349−3320a 134910.8 −332012 3.70 ⋆ unres.
J1349−3317 134915.0 −331750 2.82 ⋆ unres.
J1349−3304 134915.6 −330443 3.27 2.39 0.58 unres.
J1349−3247 134918.8 −324728 1.93 0.89 1.42 unres.
J1349−3314a 134923.9 −331408 5.83 ⋆ unres.
J1349−3323 134926.0 −332356 23.95 ⋆ unres.
J1349−3329 134927.0 −332927 0.73 ⋆ unres.
J1349−3246 134927.7 −324611 1.13 ⋆ unres.
J1349−3230 134927.9 −323010 1.72 − unres.
J1349−3238a 134931.5 −323806 1.59 − unres.
J1349−3351 134935.1 −335104 212.79 − unres.
J1349−3314b 134936.1 −331434 10.28 − unres.
J1349−3301 134940.5 −330119 2.66 ⋆ unres.
J1349−3314c 134940.6 −331428 9.32 − unres.
J1349−3244 134940.8 −324438 1.92 ⋆ unres.
J1349−3320b 134943.1 −332018 14.86 − unres.
J1349−3238b 134958.2 −323849 5.56 7.35 −0.51 unres.
J1349−3245 134958.9 −324504 7.02 4.55 0.80 unres.
J1350−3334 135001.2 −333422 10.00 − unres.
J1350−3302 135008.8 −330219 4.37 ⋆ res.
J1350−3311 135009.1 −331124 6.01 − unres.
J1350−3301 135012.1 −330158 1.21 ⋆ unres.
J1350−3249 135018.7 −324917 2.55 1.66 0.79 unres.
J1350−3336 135022.5 −333658 56.99 − unres.
J1350−3243 135026.8 −324338 9.22 6.16 0.74 unres.
J1350−3248a 135046.3 −324851 1.35 ⋆ unres.
J1350−3250 135051.7 −325017 1.08 0.91 0.31 unres.
J1350−3248b 135057.1 −324848 1.07 ⋆ unres.
J1351−3248 135124.6 −324849 2.06 ⋆ unres.
J1351−3238 135128.4 −323835 0.91 ⋆ unres.
J1351−3259a 135129.4 −325911 1.50 ⋆ unres.
J1351−3249 135133.8 −324949 2.80 1.31 1.39 unres.
J1351−3228a 135134.1 −322844 32.75 − unres.
J1351−3228b 135135.5 −322845 57.82 − unres.
J1351−3234 135135.5 −323413 3.42 − unres.
J1351−3247 135135.9 −324710 3.14 ⋆ res.
J1351−3259b 135141.6 −325911 3.29 ⋆ unres.
J1351−3313 135143.8 −331348 1.67 − unres.
J1351−3303 135144.0 −330307 0.94 ⋆ unres.
J1351−3310 135146.2 −331042 2.79 − unres.
J1351−3301 135156.9 −330146 1.60 ⋆ unres.
VenturiT.etal.:TheA3571ClusterComplex 9
Table3.−continued
Name RA DEC S S a 22 Morph.
J2000 J2000 22cm 13cm 13
h m s ◦ ′ ′′ mJy mJy
J1351−3240 135159.8 −324019 2.02 ⋆ unres.
J1351−3229 135159.9 −322924 2.94 − unres.
J1352−3314 135208.0 −331445 20.42 − res.
J1352−3315 135209.1 −331526 26.16 − res.
J1352−3236 135214.2 −323644 1.22 ⋆ unres.
J1352−3243a 135216.5 −324338 1.24 ⋆ unres.
J1352−3245 135224.8 −324537 12.42 6.49 1.19 res.
J1352−3308 135232.9 −330849 2.37 ⋆ unres.
J1352−3306 135233.1 −330601 6.52 2.95 1.46 unres.
J1352−3243b 135234.1 −324332 6.56 3.51 1.15 unres.
J1352−3244 135234.9 −324433 11.00 6.13 1.07 unres.
J1352−3248 135240.2 −324856 1.34 1.07 0.41 unres.
J1352−3230a 135242.6 −323051 5.23 − unres.
J1352−3302 135243.5 −330229 8.13 8.92 −0.17 unres.
J1352−3230b 135246.3 −323024 10.22 − unres.
J1352−3301 135250.2 −330158 16.70 3.32 2.96 res.
J1352−3251 135250.5 −325124 232.18 145.41 0.86 unres.
J1352−3304 135256.6 −330440 37.85 27.57 0.58 unres.
J1353−3229 135308.4 −322927 5.81 − unres.
J1353−3228 135320.1 −322803 6.00 − unres.
J1353−3238 135322.5 −323811 1.44 ⋆ unres.
J1353−3239 135327.2 −323917 4.68 ⋆ unres.
J1353−3300 135345.5 −330001 4.18 ⋆ unres.
J1354−3251 135424.1 −325102 14.66 − res.
NotestoTable3.
⋆Nondetectionsat13cm,i.e,S13≤0.65mJyintheimagenotcorrectedfortheprimarybeamattenuation.
♦Thepositionofthisradiosourcewastakenfromthe13cmimage,wherethenucleusofthedoublestructureisclearlyvisible.
♣Thissourceshowsadoublemorphologyinthe13cmimage.
10 VenturiT.etal.:TheA3571ClusterComplex
Table4.Opticalidentifications.
Radio RA DEC S S a 22 logP RadioType Cluster
J2000 J2000 22cm 13cm 13 22cm
h m s ◦ ′ ′′ mJy mJy WHz−1
Optical RAJ2000 DECJ2000 bj Cat. Bj R vr
h m s ◦ ′ ′′ kms−1
J1346−3252 134613.7 −325228 3.90 unres.
134613.8 −325226 21.80 A 0.90
J1346−3231 134625.9 −323139 5.57 unres.
134625.9 −323139 19.40 C 0.06
J1346−3237b 134634.3 −323708 1.89 unres. A3571
134634.3 −323705 18.13 C 1.34
J1346−3235 134638.8 −323555 12.59 res.
134638.8 −323554 20.31 C 0.65
J1346−3303 134639.4 −330344 1.04 unres. A3571
134639.5 −330344 17.78 C 1.04
J1346−3248 134653.4 −324822 1.69 res.
134653.3 −324820 19.95 C 0.99
J1346−3346 134659.0 −334616 4.47 unres.
134658.9 −334612 12.51a C 1.60
J1347−3252 134724.6 −325215 24.23 11.23 1.41 D
134724.3 −325213 21.98? C 1.00b
J1347−3256 134725.3 −325610 1.34 21.35 unres. A3571
134725.3 −325613 15.78 C −19.59 1.57 11850
J1347−3229 134726.5 −322930 54.39 res.
134726.5 −322930 20.42 C 0.08
J1347−3251 134728.5 −325154 4.05 2.52 0.87 21.82 unres. A3571
134728.3 −325154 13.81 C −21.53 1.00 11669
J1347−3339 134737.3 −333927 7.13 7.76 −0.16 res.
134737.5 −333930 22.46 1.96
J1347−3259 134753.1 −325901 1.08 21.20 unres. A3571
134753.1 −325902 15.18 C −20.03 0.32 11100
J1347−3236 134754.2 −323659 14.18 10.44 0.56 unres. A3571
134754.2 −323635 19.77 C 0.08
J1347−3301 134756.8 −330106 9.09 6.12 0.73 unres.
134756.7 −330109 17.98 A 1.33
J1348−3255 134816.1 −325533 0.75 unres.
134816.2 −325533 21.77 A 0.20