Sunyaev-Zel'dovich observations of LoCuSS clusters with the Arcminute Microkelvin Imager: high X-ray luminosity sample

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by  The AMI Consortium

Mon.Not.R.Astron.Soc.000,1–17(0000) Printed31January2011 (MNLATEXstylefilev2.2)
Sunyaev-Zel’dovich observations of LoCuSS clusters with the
Arcminute Microkelvin Imager: high X-ray luminosity sample ⋆
1
AMI Consortium: Timothy W. Shimwell1†, Carmen Rodr´ıguez-Gonza´lvez1‡,
1
0 Matthew L. Davies1, Farhan Feroz1, Thomas M. O. Franzen1, Keith J. B. Grainge1,2,
2
n Michael P. Hobson1, Natasha Hurley-Walker1, Anthony N. Lasenby1,2, Malak Olamaie1,
a
J Guy Pooley1, Richard D. E. Saunders1,2, Anna M. M. Scaife3, Michel P. Schammel1,

8 Paul F. Scott1, David J. Titterington1, Elizabeth M. Waldram1
2
1AstrophysicsGroup,CavendishLaboratory,JJThomsonAvenue,CambridgeCB30HE

] 2KavliInstituteforCosmologyCambridge,MadingleyRoad,Cambridge,CB30HA
O
3DublinInstituteforAdvancedStudies,31FitzwilliamPlace,Dublin2,Ireland
C
.
h
p
Accepted—;received—;inoriginalform31January2011
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o
r
t
s ABSTRACT
a WepresentobservationsfromtheSmallArrayoftheArcminuteMicrokelvinImager(AMI)
[ of eighthighX-ray luminositygalaxycluster systems selected from the LocalCluster Sub-

1 structureSurvey(LoCuSS)sample.WedetecttheSunyaev-Zel’dovich(SZ)effectinsevenof
v theseclusters.Withtheassumptionsthatgalaxyclustersareisothermal,haveadensityprofile
0 describedbyasphericalb -modelandobeythetheoreticalM-Trelation,weareabletoderive
9 cluster parameters at r from our SZ data. With the additional assumption of hydrostatic
200
5 equilibriumweareabletoderiveparametersatr .We presentposteriorprobabilitydistri-
500
5 butionsforclusterparameterssuchasmass,radiusandtemperature(T ).Combiningour
SZ,MT
1. sample with that of AMI Consortium: Rodr´ıguez-Gonza´lvez et al. (2011) and using large-
0 radiusX-raytemperatureestimates(TX)fromChandraandSuzakuobservations,wefindthat
1 thereisreasonablecorrespondencebetweenT andT valuesatlowT ,butthatforclus-
X SZ,MT X
1 terswithT abovearound6keVthecorrespondencebreaksdownwithT exceedingT ;
X X SZ,MT
: westressthatthisfindingisbasedonjusttenclusters.
v
i
X Keywords:
cosmology: observations - Sunyaev-Zel’dovich – galaxies:clusters – X-ray – cosmic mi-
r
a crowave background– galaxies:clusters:individual (Abell 586, Abell 611, Abell 773, Abell
781,Abell1413,Abell1758,Zw1454.8+2233andRXJ1720+2638)
1 INTRODUCTION We have imaged a subset of LoCuSS in the Sunyaev-
Zel’dovich (SZ; Sunyaev & Zeldovich 1972) effect with the Ar-
TheLocal Cluster Substructure Survey(LoCuSSseeSmithet al.
cminute Microkelvin Imager (AMI; see e.g. AMI Consortium:
2003,2005)sampleofclusterscontains164clusterswithredshifts
Zwart et al. 2008) centred at 16 GHz. The SZ signal arises from
between0.142and0.295. TheLoCuSSaimstomeasuretherela-
theinverseComptonscatteringofcosmicmicrowavebackground
tionshipbetweenthestructureofgalaxyclustersandtheevolution
(CMB) photons by the hot cluster plasma (see e.g. Birkinshaw
of the hot gas and galaxies that inhabit them using gravitational
1999andCarlstrom,Holder&Reese2002),withasurfacebright-
lensing data and other observations spanning theelectromagnetic
ness that is independent of redshift and dependencies on plasma
spectrum from theradio toX-ray. Example LoCuSSanalysis pa-
density and temperature that are different to those for e.g. X-ray
persrelevant tothisworkareMarroneetal.(2009) andZhanget
bremsstrahlungemission.
al.(2010).
Hereafter,weassumeaconcordanceL CDMcosmologywith
⋆ShWimewreelqlueetsatl.t2h0a1t1a’ny reference to this paper cites ‘AMI Consortium: W m=0.3,W L =0.7andH0=100kms−1Mpc−1.Thedimensionless
† E-mail:[email protected] HubbleparametersaredefinedashX =H0/(Xkms−1Mpc−1).All
‡ E-mail:[email protected] coordinatesaregivenatequinoxJ2000.
2 Shimwellet al.
2 CLUSTERSAMPLE dard AIPS 1 taskstoimagethecontinuumandindividual-channel
UVFITS data. On the continuum maps we detected sources at
Ig×nr1ea0tht3ei7srWtphaoapvneerr20wth◦eea0fno.d1c-u2asn.4oXnke-rVLaoybCaluunSmdSiinncoltsuhisteytecr(lsLusXwt)eirtghrreeasattdeferractmlhinaeant(iao1cn1- y>s4asnLdApaenadkcflautaxl,ogSu0e.dTothedestoeurmrcienerigwhhteatshceernasiosonu,rxcse,disecelxinteantidoend,
inour LA maps wecompared the measured source areawiththe
cordingtoEbelingetal.1998,2000,usingh50=1).Radiosource LAsynthesizedbeam.Forextendedsourceswecataloguedthein-
contamination can make it difficult to observe the SZ effect at
tegrated flux rather than the peak flux. We measured the flux of
16GHzandwehavenotstudiedtheclusterswithsourcesbrighter
each source ineach channel map and assumed apower law rela-
than 10 mJy/beam within 10′ of the cluster X-ray centre. Note tionship between flux and frequency (S(cid:181) n −a ) to determine the
thatourredshiftscorrespondtothosecitedinEbelingetal.(1998, sourcespectralindex, a .Thenumber of>4s sourcesdetected
2000). Wepresent results from the analysis of eight galaxy clus- LA
inourLAobservationstowardstheeightclustersisshowninTable
ter systems; Table 1 shows the coordinates, redshifts and X-ray
2.
luminosities of our selected LoCuSS clusters. A companion pa-
per(AMIConsortium:Rodr´ıguez-Gonza´lvezetal.2011)presents
resultsfrom11 LoCuSSclusterswithanX-rayluminosity inthe
range7-11×1037W(h50=1).
4 BAYESIANANALYSIS
ToanalysetheAMIclusterobservationsweuseaBayesiananaly-
sismethodology(Marshalletal.2003andFerozetal.2009).This
3 INSTRUMENT,OBSERVATIONSANDSOURCE
FINDING Bayesian analysis uses MULTINEST (Feroz & Hobson 2008 and
Feroz, Hobson, & Bridges 2009) to efficiently explore the multi-
3.1 TheArcminuteMicrokelvinImager(AMI) dimensional parameter space andtocalculate Bayesian evidence.
This analysis has been applied to pointed observations of known
AMIconsistsofapairofaperture-synthesisinterferometricarrays
clusters in AMI Consortium Rodr´ıguez-Gonza´lvez et al. (2010),
located near Cambridge. The Small Array (SA) is optimised for
AMIConsortium:Zwartetal.(2010)&Rodr´ıguez-Gonza´lvezetal.
SZimagingwhiletheLargeArray(LA)isusedtomeasureradio
(2011)andalsotodetectpreviouslyunknownclustersinShimwell
sourcesthatcontaminatetheSZ-effectintheSAobservations.AMI
etal.InthispaperweusethesamemodelasShimwelletal.,thedif-
isdescribedindetailinZwartetal.(2008).
ferencesbetweenthismodelandpreviousmodelsareexplainedin
AMIConsortium:Olamaieetal.(2010)andRodr´ıguez-Gonza´lvez
etal.(2010).
3.2 Observations ThepriorsthatweuseinourBayesiananalysisareshownin
Table3.
SApointedobservationscentredattheX-rayclusterposition(Table
1)foroureightclustersweretakenduring2007-2010. Theobser-
vationlengthswereintherange20-90hoursperclusterbeforeany
flaggingof thedata; thenoiseson theSA mapsreflecttheactual
observationtimeused. 5 SASOURCESUBTRACTIONANDMAPPING
With the SA we observed phase calibrators every hour and
used bi-daily observations of 3C48 or 3C286 for amplitude cali- Source subtraction is performed using the software package
bration; the assumed flux densities for the calibrator sources are MUESLI.ThisperformsthesamefunctionastheAIPStaskUVSUB
consistent withtheRudy et al. (1987) model of Mars– seeAMI but it is optimised for processing AMI data. For both the LA
Consortium:Franzenetal.(2010). sourcesandthesourcesmodelledinourBayesiananalysisweuse
WiththeLAwetypically conduct 61+19pt hexagonal raster thesourceposition,meanfrequency,spectralindexandcentralflux
observations centred on thecluster X-rayposition. The 61 point- value to subtract the appropriate flux for each source from each
ingcentresareseparatedby4′;theinner19pointingsareobserved channel of the SA UVFITS file. To perform this subtraction from
forapproximatelysixtimeslongerthantheouter42pointings.We our non-primary-beam-corrected SA UVFITS we make use of an
observed phase calibrators every ten minutes. Observations were accurateSApowerprimarybeammodel.
taken over 2009-2010 and each cluster was observed for 10-25 Weuse AIPS toproduce theSAmaps andapply no primary
hoursbeforeanyflaggingofthedata.Formoredetailsontheras- beam correction i.e. the SA thermal noise is constant across the
teringtechniquesandcalibrationseeFranzenetal.(2010). map.AlltheSAmapspresentedherehavecontourlevelschanging
All our cluster data were passed through REDUCE,the stan- linearlyfrom2-10s SA;positivecontoursaresolidlinesandnega-
dard AMI data reduction package which is discussed in detail in tivecontoursaredashed lines.TheSAsynthesizedbeamFWHM
e.g. AMI Consortium: Davies et al. (2009). Thermal noise levels isshowninthebottomleftcornerofourSAmaps.Wealsopresent
fortheSAandtheLAmaps(s ands respectively),andphase thesource-subtractedmapswithauvtaperof600kl (aGaussian
SA LA
calibratorsthatwehavetakenfromtheJodrellBankVLASurvey taperofvalue1arelowuvfallsto0.3at600kl )sincetheshorter
(Patnaiketal.1992,Browneetal.1998andWilkinsonetal.1998) SAbaselinesaremoresensitivetothelargeangularsizeoftheSZ-
aresummarisedinTable2. effectsignal.MapsbeforesourcesubtractionhavebeenCLEANed
withasingleboxovertheirtotalextents,whilstsource-subtracted
mapshavebeenCLEANedwithatightboxaroundtheSZsignals.
3.3 LAmappingandsourcefinding
Our LA map-making and source-finding procedures follow AMI
Consortium: Shimwell et al. (2010) exactly. We applied stan- 1 http://www.aips.nrao.edu
SZobservationsofLoCuSS clusterswith theAMI:highX-rayluminositysample 3
Table1.Coordinates, redshifts andX-rayluminosities ofthe observedLoCuSSclusters. Notethat Abell1758Bis included eventhough itisbelow our
luminositycut;thisisbecauseitiswithinthefieldofviewofourAbell1758Aobservations.RedshiftsandX-rayluminositiesaretakenfromEbelingetal.
(1998,2000).
Cluster Rightascension Declination Redshift X-rayluminosity Alternativeclusternames
(J2000) (J2000) in1037W
(h50=1)
Abell586 07:32:12 +31:37:30 0.171 11.12
Abell611 08:00:56 +36:03:40 0.288 13.60
Abell773 09:17:54 +51:42:58 0.217 13.08 RXJ0917.8+5143
Abell781 09:20:25 +30:31:32 0.298 17.22
Abell1413 11:55:18 +23:24:29 0.143 13.28
Abell1758B 13:32:29 +50:24:42 0.280 07.25
Abell1758A 13:32:45 +50:32:31 0.280 11.68
Zw1454.8+2233 14:57:15 +22:20:34 0.258 13.19 Z7160
RXJ1720.1+2638 17:20:10 +26:37:31 0.164 16.12
Table2.DetailsofAMIobservations.
Cluster s SA s LA NumberofLA4s LAsources LAphasecalibrator
(mJy) (mJy)
Abell586 0.172 0.09 23 J0741+3112
Abell611 0.106 0.07 23 J0808+408
Abell773 0.133 0.09 09 J0903+468orJ0905+4850
Abell781 0.116 0.07 24 J0925+3127orJ0915+2933
Abell1413 0.130 0.09 17 J1150+2417
Abell1758A 0.115 0.08 14 J1349+536
Abell1758B 0.130 0.08 14 J1349+536
Zw1454.8+2233 0.100 0.10 16 J1513+2338
RXJ1720.1+2638 0.084 0.10 17 J1722+2815
6 RESULTS cluster mass from weak lensing by applying a Navarro, Frenk &
White (NFW; Navarro, Frenk, & White 1996) profile. They find
Ftroarcteioacnh, acnludstpeorswteeriporrepseronbtaSbAilimtyapdsisbtreibfourteioannsdoaffttehresloaurgrcee-sscuable- MT(r2500)=2.41−+00..4415×1014M⊙, whilst at large radii they find
clusterparametersobtainedfromrunningtheSAdatathroughour MT(r500)=4.74−+11..1440×1014M⊙(usingh70=1).
Abell586hasbeenstudiedextensivelyintheX-raye.g.Allen
Bayesian analysis software. The derived cluster parameters are
(2000)andWhite(2000).Arecentanalysisofthetemperaturepro-
giveninTable4.WealsopresentChandraimagestakenfromthe
file(Cypriano et al. 2005) shows how the temperature falls from
Chandra Data Archive. All maps are displayed with right ascen-
≈9keVattheclustercentreto≈5.5keVataradius≈280′′.Cypri-
siononthex-axisanddeclinationonthey-axis.InSection6.9we
anoetal.haveusedtheGeminiMulti-ObjectSpectrographtogether
compareourderivedclustertemperatureswithlarge-radiusX-ray
temperatures(r≈500kpc)takenfromtheliterature. with X-ray data taken from the Chandra archive to measure the
propertiesofAbell586.Theycomparemassestimatesderivedfrom
thevelocitydistributionandfromtheX-raytemperatureprofileand
findthatbothgiveverysimilarresults,Mg≈0.46×1014M⊙within
6.1 Abell586 1.3h−1Mpc.Theysuggestthattheclusterissphericalandrelaxed
70
OurAMISAmapsandtheparameterswemeasurearepresented withnorecentmergers.TheelongationoftheSZsignalonourmap
inFigure1.WehaveoverlayedourmaponanX-rayChandraim- (Figure1)suggestsnon-sphericity.
age;theclustercentroidsmatchandweobserveanextensionofthe
clustertowardsthesouth.
6.2 Abell611
The SZeffect fromAbell 586 has previously been observed
with OVRA/BIMA by LaRoque et al. (2006) and Bonamente et We present AMI SA maps, large-scale cluster parameters and a
al.(2006).LaRoqueetal.applyanisothermalb -modeltoSZand Chandra image of Abell 611 in Figure 2. The Donnarumma et
Chandra X-ray observations and find Mg(r2500)=2.49±0.32× al. (2010) analysis of theChandra achive data shows that theX-
1013M⊙ andMg(r2500)=2.26−+00..1113×1013M⊙ respectively(using ray isophotes are quite circular, the surface brightness profile is
h70=1).Inaddition,theydetermineanX-rayspectroscopictem- smooth and the brightest cluster galaxy lies at the centre of the
peratureoftheclustergasof≈6.35keVbetweenaradiusof100kpc X-ray emission. These results indicate that the cluster is relaxed.
andr ;r istheradiusatwhichtheaveragecluster density From the X-ray data, the cluster mass was estimated using an
2500 2500
falls to 2500 times the critical density at that redshift and is de- NFW profile, spherical symmetry and hydrostatic equilibrium to
terminedfromChandraobservationsbyBonamenteetal.(2006). be 9.32±1.39×1014M⊙ (withina radius of 1.8±0.5 Mpc). How-
In comparison, Okabe et al. (2010) use Subaru to calculate the ever, the Donnarumma et al.analysis of strong lensingdata indi-
4 Shimwellet al.
Abell586
y/arcsec0−−150000
1000
−1r/hkpcc 246800000000
2.5
2
1.5
b 1
0.5
MSun180
−1M(r)/hT200 246
0.15
−1f/hgas,r20000.0.15
−50x0/a0rcse5c0 −1y000/−a5rc0sec0 rc/h5−010kpc10000.5 1b.5 2.5MT(r200)5/h−1MSu1n0 0.0fg5as,r2000./1h−10.15
2 4 6 8 10 2 4 6 8 10
MT(r500)/h−1MSun x 1014 Mg(r500)/h−2MSun x 1013
2 4 6 8 10 0 0.1 0.2 0.3
Mg(r200)/h−2MSun x 1013 fg(r500)/h−1
0.5 1 1.5 0.5 1 1.5
r500/h−1Mpc r200/h−1Mpc
0 2 4 6 8 10
T/KeV
Figure1.ThetopleftimageshowstheSAmapbeforesubtraction,themapinthemiddlelefthashadthesourcesremoved,thetoprightpanelshowsthecluster
parametersthatwesamplefrominourBayesiananalysisandthemiddlerightplotpresentsseveralclusterparametersderivedfromoursamplingparameters.
TheimageatthebottomshowstheChandraX-raymapoverlayedwithSAcontours.
SZobservationsofLoCuSS clusterswith theAMI:highX-rayluminositysample 5
Table3.PriorsusedinourBayesiananalysis.
Parameter Prior
Sourceposition(xs) +or×:Delta-functionusingtheLApositions.
△:GaussiancentredontheLApostionswiths =5′′.
Sourcefluxdensities(S0/Jy) ×or△:GaussiancentredontheLAcontinuumvaluewithas of0.4S0.
+:Delta-functionontheLAvalue.
Sourcespectralindex(a ) ×or△:GaussiancentredonthevaluecalculatedfromtheLAchannelmapswiths astheLAerror.
+:Delta-functionontheLAvalue.
Redshift(z) Delta-functionontheX-rayvalue(Table1).
Coreradius(rc/h−1010kpc) Uniformbetween10and1000.
Beta(b ) Uniformbetween0.3and2.5.
Mass(MT,r200/h−1010M⊙) Uniforminlogspaceover,(0.32−50)×1014M⊙h−1010.
Gasfraction(fg) Gaussianpriorcentredon0.086,s =0.02(Komatsuetal.2010).
Clusterposition(xc) GaussianpriorontheX-rayposition,s =60′′(Table1).
Table4.Derivedvaluesforclusterparameters.
Clustername MT(r200) MT(r500) Mg(r200) Mg(r500) r200 r500 fg(r500) TSZ,MT(r200)
×1014h−1010M⊙ ×1014h−1010M⊙ ×1013h−1020M⊙ ×1013h−1020M⊙ h−1010Mpc ×10−1h−1010Mpc ×10−1h−1010 keV
Abell586 5.1±2.4 2.1±1.1 4.3±2.0 2.6±0.8 1.2±0.2 6.6±1.1 1.4±0.4 5.2±1.6
Abell611 4.0±0.8 2.0±0.5 3.5±0.6 2.8±0.3 1.1±0.1 6.3±0.5 1.5±0.4 4.5±0.6
Abell773 3.6±1.3 1.7±0.7 3.1±1.1 2.1±0.5 1.1±0.1 6.0±0.8 1.4±0.4 4.1±1.0
Abell781 4.1±0.8 2.0±0.5 3.6±0.6 2.9±0.4 1.1±0.1 6.3±0.5 1.5±0.4 4.5±0.6
Abell1413 4.0±1.0 1.9±0.6 3.5±0.8 2.7±0.4 1.1±0.1 6.6±0.7 1.5±0.4 4.4±0.8
Abell1758B 4.4±2.2 2.2±1.2 3.7±1.8 2.2±0.6 1.1±0.2 6.4±1.2 1.2±0.4 4.6±1.5
Abell1758A 4.1±0.7 2.5±4.4 3.6±0.5 3.4±0.4 1.1±0.1 6.8±0.4 1.4±0.3 4.5±0.5
RXJ1720.1+2638 2.0±0.4 1.2±0.2 1.7±0.3 1.6±0.3 0.9±0.1 5.6±0.4 1.4±0.3 2.8±0.4
catesthattheclustermasscouldbecloserto4.68±0.31×1014M⊙ fromthatbyZwartetal.(2010)whosamplefromtemperatureand
(withinaradiusof1.5±0.2 Mpc.Notethatthevaluesquotedfrom M andderiveM undertheadditionalassumptionofhy-
g,r200 T,r200
Donnarummaetal.areanexampleoftheirmassestimates;fromfit- drostatic equilbrium. Instead we sample from M and f
T,r200 g,r200
tingdifferentmodelstheyfindestimatedmassvariessignificantly andcalculateT usingtheM-TscalingrelationgiveninRodr´ıguez-
(between 9.32–11.11×1014M⊙ for the X-ray mass and between Gonza´lvezetal.(2010). Thedifferencesbetweenthesetwomod-
4.01–6.32×1014M⊙ for the lensing mass). Their mass estimates elsaredescribedindetailbyOlamaieetal.whodemonstratethat
useh70=1.SeveralotheranalysesofChandradataproducecom- the mass estimated using the technique in this paper produces a
parablemassestimates(e.g.Schmidt&Allen2007,Morandi,Et- more reliable value and that the Zwart et al. (2010) analysis un-
tori&Moscardini2007,Morandi&Ettori2007andSandersonet derestimates the values for M and f . The values of b
g,r200 g,r200
al.2009). andrc/h−1010kpcpresentedhereagreewiththoseintheZwartetal.
Romano et al. (2010) perform a weak lensing analysis of (2010)analysis.
Abell 611 using data from the Large Binocular Telescope. With Wefindnosignificantcontaminationfromradiosourcesand
anNFWprofiletheyestimateMT,r200 =4–7×1014M⊙ andr200= detect thecluster withahigh signal-to-noise ratio.A comparison
1400−1600kpc,forh70=1.Theseareinagreementwiththeval- oftheSZ-effectimageandtheChandramapshowsthatthecentres
uesobtainedfromSubaruweaklensingobservationsbyOkabeet oftheSZandX-rayemissionarecoincident.
al.
Using GMRT observations Venturi et al. (2008) concluded
that Abell 611 has no radio halo at 610MHz. Abell 611 has also 6.3 Abell773
previously been observed intheSZat15 GHzbyGrainger et al.
InFigure3weshow theAMISAmapsofAbell773, aChandra
(2002)andZwartetal.(2010),andat30GHzbyBonamenteetal.
X-ray map and the cluster parameters derived from our analysis.
(2004),Bonamenteetal.(2006)andLaRoqueetal.
TheSZeffectassociatedwithAbell773hasbeenobservedseveral
FromouranalysisoftheAMISAobservationsofAbell611 times(Graingeet al.1993, Carlstrom,Joy, &Grego1996, Bona-
presented in this paper we find that MT,r200 = 4.0−+00..43×1014M⊙. menteetal.2006,LaRoqueetal.andSaundersetal.2003).Most
Wenotethatthemassobtainedissignificantlysmallerthanthere- recently,Zwartetal.(2010)observedtheclusterandfoundaclus-
sultgiveninZwartetal.(2010); however, theirMT estimatesare ter mass of MT,r200 = 1.9−+00..43×1015M⊙ using h70 =1; however,
biased high. The bias occurs because they used a low-radius X-
theirM estimatesarebiasedhigh–seeSection6.2.
T
ray temperature as a constant temperature throughout the cluster, Inspectionofa10′×10′ regionoftheSloanDigitalSkySur-
asisexplainedbythemandinOlamaieetal.(2010).TheSZmaps vey(SDSS2)centredonAbell773revealsacomplexgalaxydistri-
presentedinthispaperaresimilartothoseinZwartetal.(2010);
bothsetsofobservationsindicatethattheclusterisextendedinthe
NWdirection.However,theanalysispresentedinthispaperdiffers 2 FundingfortheSDSSandSDSS-IIhasbeenprovidedbytheAlfredP.
6 Shimwellet al.
A611
40
y/arcsec0 200
−20
1000
−1r/hkpcc 246800000000
2.5
2
1.5
b 1
0.5
MSun180
−1M(r)/hT200 246
0.14
−1f/hgas,r2000000...001.1682
−20x0/a0rcse2c0 −20y00/arc2s0ec40 rc/h5−010kpc10000.5 1b.5 2.5MT(r200)5/h−1MSu1n0 0.0fg6as,r020.01/h−10.14
2 4 6 8 10 2 4 6 8 10
MT(r500)/h−1MSun x 1014 Mg(r500)/h−2MSun x 1013
2 4 6 8 10 0 0.1 0.2 0.3
Mg(r200)/h−2MSun x 1013 fg(r500)/h−1
0.5 1 1.5 0.5 1 1.5
r500/h−1Mpc r200/h−1Mpc
0 2 4 6 8 10
T/KeV
Figure2.ThetopleftimageshowstheSAmapbeforesubtraction,themapinthemiddlelefthashadthesourcesremoved,thetoprightpanelshowsthecluster
parametersthatwesamplefrominourBayesiananalysisandthemiddlerightplotpresentsseveralclusterparametersderivedfromoursamplingparameters.
TheimageatthebottomshowstheChandraX-raymapoverlayedwithSAcontours.
SZobservationsofLoCuSS clusterswith theAMI:highX-rayluminositysample 7
butionwithsomeEWextension.Ourobservationssupportthisex- et al.2006). These analyses indicate that Abell 1413 isarelaxed
tension,butthereisnodetailedcorrespondencebetweenthegalaxy cluster with no evidence of recent merging despite its elliptical
andgasdistributions.TheChandraobservationsappeartoshowlit- morphology.BetweentheX-rayobservationsthereisgoodagree-
tleifanysuchextension.Wefindnosignificantcontaminationfrom ment in the temperature and density profiles of the cluster out to
radiosourcesanddetecttheclusterwithahighsignaltonoiseratio. half the virial radius. Hoshino et al. measure the variation of the
For this cluster, Barrena et al. (2007) present an intensive electrontemperaturewithradius,findingatemperatureof7.5keV
study of the optical data from the Telescopio Nazionale Galileo at the centre and 3.5keV at r200. They assume spherical symme-
(TNG) telescope and X-ray data from the Chandra data archive. try,anNFWdensityprofileandhydrostaticequilibriumtocalcu-
Theyfindtwopeaksinthevelocitydistributionoftheclustermem- lateMT,r200 = 6.6±2.3×1014h−701M⊙; where r200 = 2.24h−701Mpc.
berswhichareseparatedby2′alongtheE-Wdirection.Twopeaks Zhangetal.useXMM-NewtontostudyAbell1413andfindM
500
canalsobeseenintheX-ray,althoughthesearealongtheNE-SW =5.4±1.6×1014M⊙,wherer500=1.18Mpc;theyassumeisother-
direction.Barrenaetal.estimatethevirialmassoftheentiresys- mality,sphericalsymmetryandh70=1.
temtobeMvir =1.2-2.7×1015h−701M⊙.Giovannini, Tordi,&Fer- Recent VLA observations (Govoni et al. 2009) indicate that
etti(1999)reportedtheexistenceofaradiohaloinAbell773.This thereisdiffuse1.4-GHzemissionassociatedwiththecluster–this
feature, typical of cluster mergers, was confirmed with 1.4 GHz maybeduetoamini-haloaroundthecluster.
VLA observations by Govoni et al. (2001). Zhang et al. (2008) From the SA observations we detect the SZ decrement at
usedXMM-NewtontostudyAbell773andfoundM =8.3±2.5 high significance. Wedetermine the cluster mass tobe M =
500 T,r200
×1014M⊙, where r500 = 1.33Mpc; they assumed isothermality, 4.0−+00..63×1014h−1010M⊙ andr200 =1.14−+00..54h−1010kpc;boththeseval-
spherical symmetry and h70 =1. Govoni et al. (2004) present a uesarecomparablewiththeHoshinoetal.results.
ChandratemperaturemapandanX-rayimageofAbell773;they Thesourceenvironment aroundtheclusterat16GHzisrea-
estimate a mean temperature of 7.5±0.8keV within a radius of sonable:thebrightestsourceis14mJy(11:55:36.63+23:13:50.1),
800kpc(h70=1). but this is 700′′ from the cluster X-ray centre. After this bright
sourceissubtractedfromour dataweareleftwithalow levelof
residual flux density on the map; it is unlikely that this residual
6.4 Abell781
fluxsignificantlycontaminatesourclusterdetectionorparameters.
AMISAmaps,derivedparametersandaChandraobservationof BoththeX-raymap andtheSZimageindicatethat theclusteris
the Abell 781 cluster are presented in Figure 4. From X-ray ob- ellipticalandextendedintheN-Sdirection.
servations with Chandra and XMM-Newton (Sehgal et al. 2008)
it is apparent that Abell 781 is a complex cluster system. The
6.6 Abell1758
main cluster is surrounded by three smaller clusters, two to the
East of the main cluster and one to the West. They estimate the AnanalysisofROSAT imagesclearlyshowsthatthissystemcon-
mass of the clusters assuming a NFW matter density profile; the sists of two interacting clusters, Abell 1758A and Abell 1758B,
results indicate that the cluster mass of Abell 781 within r500 is separatedby8′(Rizzaetal.1998).InFigure6wepresentasingle
5.2+−00..37×1014M⊙fromXMM-NewtonandChandraX-rayobserva- mapthatcontains combined datafromobservations towardsboth
tionsor2.7+−10..09×1014M⊙fromtheKittPeakMayall4-mtelescope clusters and the derived parameters for cluster Abell 1758A. We
lteivnesliyn)g.Aoblsteerrnvaattiivoenlsy,(wZhhaenregre5t00ali.su1s.e09X−+M00..00M44aNnedw0t.o8n9−+o00b..s11e20rrveastpioencs- pmraepsesnftrothmebdoetrhivtehdepCahraamndertearsdafotaracrlcuhstivereAanbdelRlO17S5A8TA3.aInndFXig-urarye
to estimate M500 = 4.5 ±1.3 ×1014M⊙, where r500 = 1.05Mpc, 7weshowthederivedparametersforclusterAbell1758B.
assumingisothermalityandsphericalsymmetry.BothZhangetal. A detailedanalysis of XMM-Newtonand Chandra byDavid
andSehgaletal.useh70=1. & Kempner (2004) indicates that the clusters Abell 1758A and
The main cluster of Abell 781 is also known to contain a Abell1758Barelikelytobeinanearlystageofmergingandthat
diffuse peripheral source at 610MHz; this was observed with the bothoftheseclustersarealsoundergoingmajormergerswithother
GMRTbyVenturietal.(2008). smallersystems.ArecentanalysisofSpitzer/MIPS24m mdataby
Hainesetal.(2009)classifiesAbell1758asthemostactivesystem
theyhaveobservedatthatwavelength. Theyalsoidentifynumer-
6.5 Abell1413 oussmallermasspeaksandfilamentarystructures,whicharelikely
toindicatethepresenceofinfallinggalaxygroups,insupportofthe
We present the SA maps before and after source subtraction in
David&Kempnerobservations.Zhangetal.useXMM-Newtonto
Figure 5. We also show the derived cluster parameters and we
overlay our SZ image on a Chandra X-ray map. Abell 1413 has studyAbell1758A andfoundM500 =1.1±0.3×1015M⊙,where
r = 1.43Mpc. They assume isothermality, spherical symmetry
been observed in the X-ray by XMM-Newton (e.g. Pratt & Ar- 500
naud2005),Chandra(e.g.Vikhlininetal.2005andBonamenteet andh70=1.
al.2006) and most recentlyby thelow background Suzaku satel-
lite (Hoshino et al. 2010); SZ images have been made of Abell 6.7 Zw1454.8+2233
1413 with the Ryle Telescope at 15 GHz (Grainge et al. 1996)
andwithOVRO/BIMAat30GHz(LaRoqueetal.andBonamente Wedetectseveralsourcesclosetotheclustercentre–apointsource
withafluxdensityof7.97mJyat14:56:59.11+22:18:55.97anda
4.67mJysourceat14:57:25.38+22:37:33.03.Wedonotdetectan
SloanFoundation,theParticipatingInstitutions,theNationalScienceFoun-
dation,theU.S.DepartmentofEnergy,theNationalAeronauticsandSpace
Administration, the Japanese Monbukagakusho, the MaxPlanck Society, 3 We acknowledge the use of NASA’s SkyView facility
andtheHigherEducation FundingCouncil forEngland.TheSDSSWeb (http://skyview.gsfc.nasa.gov) located at NASA Goddard Space Flight
Siteishttp://www.sdss.org/. Center.
8 Shimwellet al.
Abell773
50
y/arcsec0 0
−50
1000
−1r/hkpcc 246800000000
2.5
2
1.5
b 1
0.5
MSun180
−1M(r)/hT200 246
0.15
−1f/hgas,r20000.0.15
−5x00/arc0sec50 −50y0/a0rcsec50 rc/h5−010kpc10000.5 1b.5 2.5MT(r200)5/h−1MSu1n00.0f5gas,r2000./1h−10.15
2 4 6 8 10 2 4 6 8 10
MT(r500)/h−1MSun x 1014 Mg(r500)/h−2MSun x 1013
2 4 6 8 10 0 0.1 0.2 0.3
Mg(r200)/h−2MSun x 1013 fg(r500)/h−1
0.5 1 1.5 0.5 1 1.5
r500/h−1Mpc r200/h−1Mpc
0 2 4 6 8 10
T/KeV
Figure3.ThetopleftimageshowstheSAmapbeforesubtraction,themapinthemiddlelefthashadthesourcesremoved,thetoprightpanelshowsthecluster
parametersthatwesamplefrominourBayesiananalysisandthemiddlerightplotpresentsseveralclusterparametersderivedfromoursamplingparameters.
TheimageatthebottomshowstheChandraX-raymapoverlayedwithSAcontours.
SZobservationsofLoCuSS clusterswith theAMI:highX-rayluminositysample 9
A781
100
y/arcsec0 468000
20
1000
−1r/hkpcc 246800000000
2.5
2
1.5
b 1
0.5
MSun180
−1M(r)/hT200 246
0.14
−1f/hgas,r2000000...001.1682
x00/a2rc0se4c0 y05/0arcsec100 rc/h5−010kpc10000.5 1b.5 2.5MT(r200)5/h−1MSu1n0 0.0fg6as,r020.01/h−10.14
2 4 6 8 10 2 4 6 8 10
MT(r500)/h−1MSun x 1014 Mg(r500)/h−2MSun x 1013
2 4 6 8 10 0 0.1 0.2 0.3
Mg(r200)/h−2MSun x 1013 fg(r500)/h−1
0.5 1 1.5 0.5 1 1.5
r500/h−1Mpc r200/h−1Mpc
0 2 4 6 8 10
T/KeV
Figure4.ThetopleftimageshowstheSAmapbeforesubtraction,themapinthemiddlelefthashadthesourcesremoved,thetoprightpanelshowsthecluster
parametersthatwesamplefrominourBayesiananalysisandthemiddlerightplotpresentsseveralclusterparametersderivedfromoursamplingparameters.
TheimageatthebottomshowstheChandraX-raymapoverlayedwithSAcontours.
10 Shimwellet al.
Abell1413
−20
y/arcsec0−−−−186400000
−120
1000
−1r/hkpcc 246800000000
2.5
2
1.5
b 1
0.5
MSun180
−1M(r)/hT200 246
0.14
−1f/hgas,r2000000...001.1682
0.04
−40x0/arc0sec 40−120y−08/a0rcs−e4c0 rc/h5−010kpc10000.5 1b.5 2.5MT(r200)5/h−1MSu1n00.04fg0a.s0,r8200/0h.−112
2 4 6 8 10 2 4 6 8 10
MT(r500)/h−1MSun x 1014 Mg(r500)/h−2MSun x 1013
2 4 6 8 10 0 0.1 0.2 0.3
Mg(r200)/h−2MSun x 1013 fg(r500)/h−1
0.5 1 1.5 0.5 1 1.5
r500/h−1Mpc r200/h−1Mpc
0 2 4 6 8 10
T/KeV
Figure5.ThetopleftimageshowstheSAmapbeforesubtraction,themapinthemiddlelefthashadthesourcesremoved,thetoprightpanelshowsthecluster
parametersthatwesamplefrominourBayesiananalysisandthemiddlerightplotpresentsseveralclusterparametersderivedfromoursamplingparameters.
TheimageatthebottomshowstheChandraX-raymapoverlayedwithSAcontours.