Constraints on Type Ia Supernova Models from X-ray Spectra of Galaxy Clusters

We present constraints on theoretical models of Type Ia supernovae using spatially resolved ASCA X-ray spectroscopy of three galaxy clusters: Abell 496, Abell 2199 and Abell 3571. All three clusters have central iron abundance enhancements; an ensemble of

ConstraintsonTypeIaSupernovaModels

fromX-raySpectraofGalaxyClusters

RenatoA.Dupke&RaymondE.WhiteIII

UniversityofAlabama,Tuscaloosa,AL35487-0324

arXiv:astro-ph/9907343v1 25 Jul 1999ABSTRACTWepresentconstraintsontheoreticalmodelsofTypeIasupernovaeusingspatiallyresolvedASCAX-rayspectroscopyofthreegalaxyclusters:Abell496,Abell2199andAbell3571.Allthreeclustershavecentralironabundanceenhancements;anensembleofabundanceratiosareusedtoshowthatmostoftheironinthecentralregionsoftheclusterscomesfromSNIa.TheseobservationsareconsistentwiththesuppressedgalacticwindscenarioproposedbyDupke&White(1999).Atthecenterofeachcluster,simultaneousanalysisofspectrafromallASCAinstrumentsshowsthatthenickeltoironabundanceratio(normalizedbythesolarratio)isNi/Fe≈4.WeusethenickeltoironratioasadiscriminatorbetweenSNIaexplosionmodels:theNi/Feratioofejectafromthe“ConvectiveDe agration”modelW7isconsistentwiththeobservations,whilethoseof“delayeddetonation”modelsarenotconsistentatthe90%con dencelevel.Subjectheadings:galaxies:abundances—galaxies:clusters:individual(Abell496,Abell2199,Abell3571)—X-rays:galaxies—stars:supernovae:general

We present constraints on theoretical models of Type Ia supernovae using spatially resolved ASCA X-ray spectroscopy of three galaxy clusters: Abell 496, Abell 2199 and Abell 3571. All three clusters have central iron abundance enhancements; an ensemble of

1.Introduction

TypeIasupernovaearethoughttobegeneratedbythermonuclearexplosionsofcarbon-oxygenwhitedwarfsundergoingaccretioninstellarbinarysystems(Hoyle&Fowler1960).However,thenatureoftheprogenitorbinarysystems(onewhitedwarfortwo?),themassesofthewhitedwarfs(Chandrasekharorsub-Chandrasekharmass?)andtheexplosionmechanism(s)(e.g.convectivede agration,delayed-detonation,etc.)forSNIaarestillopenquestions(forrecentreviewsseeBranch1998;Branchetal.1995;Niemeyer&Woosley1997;Nomoto,Iwamoto&Kishimoto1997;Ruiz-Lapuenteetal.1997).

TheexplosionofaChandrasekharmassC-Owhitedwarfisthoughttobeinitiatedbycarbonignitionatthecenter,followedbyasubsonicnuclear ame(de agrationwave)propagatingoutwards.Promptdetonationmodels(Arnett1969;Hansen&Wheeler1969),characterizedbysupersonicnuclear ames,arenotviablesincetheydonotproducetheintermediatemasselementswhichareobservedinSNIaspectra(Nomoto,Thielemann,&Yokoi1984;Wheeler&Harkness1990).Amongde agration(subsonicnuclear ame)models,theelementalnucleosynthesisdependsonthecharacteristicsofthe amepropagation,onshockwavesgeneratedbyinstabilitiesatthe amefrontandonthedensityatthetransitionfromde agrationtodetonation(Nomotoetal.1997b;Niemeyer&Hillebrandt1995;Niemeyer&Woosley1997).Intheclassical“W7”de agrationmodel(Nomotoetal.1984;Branchetal.1995;Harkness1991;Thielemann,Nomoto&Yokoi1986),thepropagationspeedofthe amefrontisrelativelyhigh(～15 25%ofthesoundspeed),butremainssubsonic.In“delayeddetonation”models,the amespeedisinitiallymuchlower,(～1 3%ofthesoundspeed),butrisestobecomesupersonic(Livne1993;Arnett&Livne1994a,1994b;Khokhlov1995;Niemeyer&Hillebrandt1995).In“pulsatingdetonation”models,thede agrationfailstounbindthewhitedwarf,causingapulsation,anddetonationoccursuponcontraction(Arnett&Livne1994a,1994b).

DespitetheremainingtheoreticaluncertaintiesinthemorepopularmodelsforSNIa,thereisbetteragreementintheirpredictednucleosyntheticyieldsthanintheyieldsfromvariousmodelsforSNII(Gibson,Loewenstein&Mushotzky1997).Nonetheless,signi cantdiscrepanciesstillexistbetweentheyieldpredictionsofcompetingSNIaexplosionmodels.Forexample,thenickelyieldfromtheW7modelcitedaboveis～3timesgreaterthanthosefromdelayeddetonationmodels.AccuratelydeterminingtheelementalyieldsfromSNIaiscrucialtodeterminingtherelativecontributionofdi erentsupernovaetypestothemetalenrichmentofgalaxiesandintraclustergas.Furthermore,assessingtherelativecontributionofSNIaandIIejectainintraclustergasprovidescrucialinformationfordeterminingwhichenrichmentmechanism(s)weremostdominantincontaminatingintraclustergas.InthispaperweuseX-rayspectroscopicobservationsofintraclustergastodiscriminatebetween

We present constraints on theoretical models of Type Ia supernovae using spatially resolved ASCA X-ray spectroscopy of three galaxy clusters: Abell 496, Abell 2199 and Abell 3571. All three clusters have central iron abundance enhancements; an ensemble of

competingtheoreticalmodelsforSNIa.

Intraclustergastendstobemetal-rich,withabundancesof～0.3 0.4solar.Sinceheavyelementsareproducedinsupernovae,themetalsinintraclustergasmusthavecomefromstars.However,themetalenrichmentmechanism(s)forintraclustergasremainscontroversial.Themostlikelyenrichmentmechanismsarethoughttobeprotogalacticwinds(Larson&Dinerstein1975)andrampressurestripping(Gunn&Gott1972).Theprocessesmaybedistinguishedbytheirchemistry.ProtogalacticwindswouldbeassociatedwithSNIIejecta,whilethemoresecularprocessoframpressurestrippingwouldbeassociatedwithsigni cantsupplementalamountsofSNIaejectawhichaccumulatedintheinterstellarmediumofgalaxies.

EarlyX-rayspectroscopyofintraclustergasindicatedadominanceofSNIIejecta(Canizaresetal.1982;Canizares,Markert&Donahue1988)andmorerecentASCAspectroscopyhasbeeninterpretedsimilarly(Mushotzky&Loewenstein1997;Mushotzkyetal.1996).SuchadominanceofSNIIejectasupportstheprotogalacticwindscenarioforthemetalenrichmentofintraclustergas.Furthersupportcomesfromtheobservationthatthespeci cenergyofintraclustergasisgreaterthanthatofclustergalaxies(White1991).However,theoreticaluncertaintiesintheelementalyieldsfromSNIaandSNIIallowASCAspectroscopytoalsobeinterpretedasshowingthatasmuchas50%oftheironinclusterscomesfromSNIa(Ishimaru&Arimoto1997;Fukazawaetal.1998;Nagataki&Sato1998;Dupke1998;Dupke&White1999).InadetailedstudyofAbell496,Dupke&White(1999)usedanensembleofelementalabundanceratiostoshowthatthefractionalcontributionofSNIaejectais～50%(bymass)inthebulkofthecluster,increasingto～70%inthevicinityofitscentralcDgalaxy.TheyarguedthatrampressurestrippingcouldnothavecausedthecentralabundanceenhancementinAbell496andinsteadproposedthatasecondarySNIa-drivenwind(followingamorevigorousSNII-drivenprotogalacticwind),waspartiallysuppressedinthevicinityofthecD(duetothecDbeingatthebottomofthecluster’sgravitationalpotentialandinthemidstofthehighestambientintraclustergasdensity).Ifthissuggestioniscorrect,highfractionsofSNIaejectashouldalsobefoundinotherclusterswithcentralabundanceenhancements.

InthispaperweshowthatAbell496,Abell2199,andAbell3571havecentralironabundanceenhancements.WeuseanensembleofabundanceratiostodeterminetherelativeproportionofSNIaandSNIIejectaintheircentralregionsand ndthatthemassfractionofSNIaejectarangesfrom～60 70%.Wethenfurtheranalyzethesecentralregions,wherethemetalcontaminationisdominatedbySNIaejecta,todiscriminatebetweencompetingtheoreticalmodelsforSNIa.Inparticular,weshowthattheNi/Feratiosobservedatthecentersoftheseclustersareconsistentwiththe“standard”W7

We present constraints on theoretical models of Type Ia supernovae using spatially resolved ASCA X-ray spectroscopy of three galaxy clusters: Abell 496, Abell 2199 and Abell 3571. All three clusters have central iron abundance enhancements; an ensemble of

model,butareinconsistentwiththoseofvariousdelayed-detonationmodels.

2.ClusterCharacteristics

Abell496isaBautz-MorganTypeIclusterwithanopticalredshiftofz=0.0328.AdoptingaHubbleconstantof50kms 1Mpc 1andq0=0.5,itsluminositydistanceis

1 1′197h 50Mpcand1=57h50kpc.Neithertheprojectedgalaxydistributionnorthegalaxyvelocitydistributionintheclustershowssignsofsigni cantsubstructure,sotheclusterappearstobedynamicallyrelaxed(Bird1993;Zabludo ,Huchra&Geller1990).Nulsenetal.(1982)foundasoftX-raycomponentinEinsteinSSSspectraofthisclusterandestimatedacoolingaccretionrateof～200M⊙yr 1,whichisconsistentwithlateranalyses(Mushotzky1984;Mushotzky&Szymkowiak1988;Canizaresetal.1988;Thomas,Fabian&Nulsen1987;Whiteetal.1994).InthecourseofajointanalysisofEinsteinSSSandGingaLACspectra,Whiteetal.(1994)foundacentralabundanceenhancementinAbell496,whichwaslatercon rmedbyASCAobservations(Dupke&White1999).Dupke&White(1999)alsofoundgradientsinelementalabundanceratios,indicativeofaspatialgradientintheproportionofSNIa/IIejecta.

Abell2199isaBautz-MorganTypeIclusterwithanopticalredshiftz=0.0309.Its

1 1′luminositydistanceis185h 50Mpcand1=54h50kpc.Thisclusterisamongthe10X-ray

brightestgalaxyclusters(Edge&Stewart1991;Siddiqui,Stewart&Johnstone1998).TheclusterX-rayemissioniswellcenteredatitscentralcDgalaxy,NGC6166.Neithertheprojectedgalaxydistributionnorthegalaxyvelocitydistributionshowssignsofsigni cantsubstructure(Buote&Tsai1996).PreviousX-rayanalysesofthisclusterwithEXOSAT(Edge1989),Einstein(Stewartetal.1984;Thomasetal.1987),Ginga/Einstein(Whiteetal.1994),andROSAT(Allen&Fabian1997;Siddiquietal.1998)indicatethepresenceof˙≈80 250M⊙yr 1.Inthecourseofajointacooling owwithanaccretionrateofM

analysisofEinsteinSSSandGingaLACspectra,Whiteetal.(1994)foundweakevidenceforacentralabundanceenhancementinAbell2199.ASCAobservationsoftheexternalregions(>3′)ofAbell2199havebeenpreviouslyanalyzedbyMushotzkyetal.(1996).

Abell3571(SC13444-325)isabright(Lahavetal.1989),moderatelyrich(richnessclass2)Bautz-MorganTypeIclusterwithanopticalredshiftz=0.0397.Itsluminosity

1 1′distanceis238h 50Mpcand1=69h50kpc.Quintana&deSouza(1993)suggestedthat

thegalaxypositionsandvelocitiesindicatethepresenceofseveralsubgroups.However,ASCAobservationsofthisclusterdonotshowsignsofsigni cantsubstructureswithinaradiusupto35′,whichindicatesthatthebulkoftheclustermassisvirialized(Markevitchetal.1998).Abell3571ispossiblyamemberoftheShapley8supercluster,whichisitself

We present constraints on theoretical models of Type Ia supernovae using spatially resolved ASCA X-ray spectroscopy of three galaxy clusters: Abell 496, Abell 2199 and Abell 3571. All three clusters have central iron abundance enhancements; an ensemble of

˙≈100centeredonAbell3558.AnalysisofEXOSATdataindicatedacooling owwithM

M⊙yr 1(Edge,Stewart&Fabian1992).

3.DataReduction&Analysis

TheASCAsatellitehasfourlarge-areaX-raytelescopes,eachcoupledtoitsowndetector:twoGasImagingSpectrometers(GIS)andtwoSolid-StateImagingSpectrometers(SIS).EachGIShasa50′diametercircular eldofviewandausableenergyrangeof0.7–12keV;eachSIShasa22′square eldofviewandausableenergyrangeof0.4–10keV.

BothAbell496andAbell2199wereobservedfor40ksecbyASCAinSeptemberandJulyof1993,respectively.Abell3571wasobservedfor30ksecinAugust1994.Forallthreeclustersweemployedstandardreductionprocedures,selectingdatatakenwithhighandmediumbitrates,withcosmicrayrigidityvalues≥6GeV/c,withelevationanglesfromthebrightEarthof≥20 andfromtheEarth’slimbof≥5 (GIS)or10 (SIS),andweexcludedtimeswhenthesatellitewasa ectedbytheSouthAtlanticAnomaly.RisetimerejectionofparticleeventswasperformedonGISdataandSISdatahadhotand ickeringpixelsremoved.Theresultinge ectiveexposuretimesforeachinstrumentarelistedinTable1.Weestimatedbackgroundsfromblanksky lesprovidedbytheASCAGuestObserverFacility.

WeusedXSPEC10(Arnaud1996)softwaretoanalyzetheASCAspectrafortheseclusters.Spectrawere tusingthemekalandvmekalthermalemissionmodels,whicharebasedontheemissivitycalculationsofMewe&Kaastra(cf.Mewe,Gronenschild&vandenOord1985;Mewe,Lemen&vandenOord1986;Kaastra1992),withFeLcalculationsbyLiedahl,Osterheld&Goldstein(1995).AbundancesaremeasuredrelativetothesolarphotosphericvaluesofAnders&Grevesse(1989),inwhichFe/H=4.68×10 5bynumber.Galacticphotoelectricabsorptionwasincorporatedusingthewabsmodel(Morrison&McCammon1983).Spectralchannelsweregroupedtohaveatleast25counts/channel.Energyrangeswererestrictedto0.8–10keVfortheGISand0.4–10keVfortheSIS.

SpectrafromallfourASCAinstruments(SIS0&1andGIS2&3)were tindividuallyandjointly.Sincetheindividualspectral tsareconsistentwiththejointanalysesofallfourinstruments,wewillonlydescribethejoint ts.Spectrawereextractedfromregionsassmallas2′radiusatseveraldi erentprojectedspatialdistancesfromtheclusterscenter.Thermalemissionmodels(mekal)withvariabletemperatures,overallabundances,normalizationsandabsorbingcolumndensities(wabs)werethenjointly ttoallfourspectrafromeachregion.Thenormalizationsfortheindividualspectrawereallowedto

We present constraints on theoretical models of Type Ia supernovae using spatially resolved ASCA X-ray spectroscopy of three galaxy clusters: Abell 496, Abell 2199 and Abell 3571. All three clusters have central iron abundance enhancements; an ensemble of

varyindependently,tocompensateforsmallcalibrationandspatialextractiondi erencesbetweenthefourdetectors.Sinceeachclusterhasamoderatecooling owatitscenter,wealsoaddedacooling owcomponenttothemekalthermalemissionmodelforthecentralregionofeachcluster,inordertotestthemodel-dependenceofourabundancemeasurements.Thecooling owspectralmodelcflowinXSPECischaracterizedbymaximumandminimumtemperatures,anabundance,aslopewhichparameterizesthetemperaturedistributionofemissionmeasures,andanormalizationwhichissimplythecoolingaccretionrate.Weadoptedtheemissionmeasuretemperaturedistributionthatcorrespondstoisobariccooling ows(zeroslope).Wetiedthemaximumtemperatureofthecooling owtothetemperatureofthethermalcomponent,andwe xedtheminimumtemperatureat0.1keV.Weappliedasingle(butvariable)globalabsorptiontobothspectralcomponentsandassociatedanadditional,intrinsicabsorptioncomponentwiththecooling ow,placingitattheredshiftofthecluster.Theresulting tswereallexcellent,havingreducedχ2ofχ2ν≈1.

4.

4.1.ResultsAbundanceandTemperatureDistributions

We rstusedisothermalmekalmodelstodeterminetheoverallelementalabundance(largelydrivenbyiron)ineachclusterregion.RadialdistributionsoftheseelementalabundancesareshowninFigure1andlistedinTable2;theindicatederrorsare90%con dencelimits.Resultsfortwoprojectedspatialregionsareshown,acentralregionfrom0 2′andanouterregionextendingfrom3 12′.Allthreeclustersshowmild,butsigni cant,abundanceenhancementsatthecenter.ForAbell496,theabundanceis

.04+0.03′0.53+0 0.04solaratthecenter,fallingto0.36 0.03solarintheouter3 12region(Dupke&White1999).InAbell2199,theabundancedeclinesfromacentralvalueof0.49±0.04solarto0.34±0.03solarintheouterparts.InAbell3571,thecentralabundanceis0.37±0.06solar,decliningto0.28±0.03solarintheouterregions.

WealsousedtheF-testtoassessthesigni canceoftheabundancegradientineachclusterbycomparingtheχ2of tswhichassumedtheabundanceswerethesameinthetwoprojectedspatialregions(innerversusouter)to tswhichallowedtheabundancesinthetworegionstovaryindependently.Thedi erencebetweentheχ2ofthesetwo tsmustfollowaχ2distributionwithonedegreeoffreedom(Bevington1969).We ndthatthecentralabundanceenhancementsaresigni cantwith>99.99%con dence.AscanbeseenfromTable2,theadditionofacooling owcomponentinthecentralregionsdoesnotsigni cantlychangetheabundanceestimates.

We present constraints on theoretical models of Type Ia supernovae using spatially resolved ASCA X-ray spectroscopy of three galaxy clusters: Abell 496, Abell 2199 and Abell 3571. All three clusters have central iron abundance enhancements; an ensemble of

BothAbell496andAbell2199havecleartemperaturegradientswhenisothermal

.07′mekalmodelsareused:thetemperatureinAbell496risesfrom3.24+0 0.06keVwithin2

.13′to4.40+0 0.13keVbeyond3;inAbell2199thetemperaturerisesfromacentralvalueof

3.7±0.09keVto4.14±0.06keVbeyond3′.TheseresultsareconsistentwiththoseofMushotzkyetal.(1996).TheaveragetemperatureofthegasinAbell3571is6.75±0.16keV,whichisconsistentwiththeresultsofMarkevitchetal.(1998),andthegradientwithin12′isnotsigni cantatthe90%con dencelevel.Formodelsincludingacooling owcomponentatthecenter,thetemperaturegradientsinTable2appearmuchweakerthandescribedabove,sincewequoteonlythebest- ttinginitial(upper)temperatureofthecoolinggas.

4.2.IndividualElementalAbundancesandAbundanceRatios

WealsodeterminedindividualelementalabundancesinthecentralregionofeachclusterbyusingthevmekalspectralmodelinXSPEC.Inourspectralmodel ts,theheliumabundancewas xedatthesolarvalue,whilecarbonandnitrogenwere xedat0.3solar(sinceASCAisratherinsensitivetocarbonandnitrogenandthederivedabundancesofotherelementsarenota ectedbytheparticularchoiceforcarbonandnitrogenabundances).OurobservedabundancesareshowninTable3.

ItcanbeseenfromTable3thatthebestdeterminedabundancesinallthreeclustersarethoseofiron,siliconandnickel.Argon,calciumandmagnesiumabundancesarepoorlymeasuredandarenotlisted.Oxygen,neonandsulfurabundancesarenotwellconstrainedinAbell3571.Nickelabundancesareabouttwicesolarinallthreeclusters.

ToestimatetheSNIa/IImassfraction,wewillcomparevariousobservedabundanceratiostothetheoreticalpredictionsofspeci cmodelsforSNIaandII.ForSNIaweinitiallyadopttheupdatedW7modelofNomotoetal.(1997b),whileforSNIIweusethecalculationsofNomotoetal.(1997a,1997b),whoadoptaSalpeterinitialmassfunctionoveraSNIIprogenitormassrangeof10-50M⊙.Theabundanceratiosweuseinvolveoxygen,silicon,ironandnickel.VariousobservedratiosarelistedinTable4andcomparedtothetheoreticalratiosfromthemodelsweadopt.

WedonotincludesulfurandneonintheseestimatesbecausetheirtheoreticalyieldsfromSNIIareparticularlyproblematic.IntheiranalysisofASCAspectraoffourclusters,Mushotzkyetal.(1996)observedapersistentunderabundanceofsulfurandanoverabundanceofneoncomparedtoexpectationsfromtheoreticalmodelsofsupernovayields.Dupke&White(1999)andDupke&Arnaud(1999),usingdi erenttheoretical

We present constraints on theoretical models of Type Ia supernovae using spatially resolved ASCA X-ray spectroscopy of three galaxy clusters: Abell 496, Abell 2199 and Abell 3571. All three clusters have central iron abundance enhancements; an ensemble of

modelsforSNIIyields,foundthatthetheoreticalsulfuryieldwouldhavetobereducedbyafactorof～2-4tobeconsistentwithresultsformostotherelementalratiosintheirASCAanalysesofAbell496andPerseus,respectively.Dupke&Arnaud(1999)alsofoundthattheoreticalneonyieldswouldhavetobereducedbyafactorof～2.7tobeconsistentwiththeresultsformostotherelementalratios.Therefore,toestimatetheSNIaironmassfraction,weuseonlyabundanceratiosinvolvingthebetterconstrained(observationallyandtheoretically)abundancesofiron,silicon,nickelandoxygen.

VariousabundanceratiosinthecentralregionsofAbell496,Abell2199,andAbell3571areshowninTable4,alongwiththetheoreticalexpectationsforSNIaandSNIIejecta;theerrorsassociatedwiththeobservedabundanceratiosarethepropagated1σerrors.InTable5welistthebest-constrainedabundanceratiosforeachclusteralongwiththeassociatedestimatesfortheSNIaironmassfractions;theindividualSNIaironmassfractionestimatesareconsistentwithoneanother,withintheirerrors.TheensembleaverageoftheseindividualestimatesoftheSNIaironmassfraction(weightedbytheirerrors)isalsoindicatedatthebottomofTable5foreachcluster.(InAbell3571,theoxygenabundanceisnotwellconstrained,sowehavenotincludeditinthecalculationoftheensembleaverage.)Evidently,thecentralregionsofallthreeclustersaresubstantiallyenrichedbySNIaejecta,withSNIaironmassfractionsof73±5%,74±7%and58±17%inAbell496,Abell2199andAbell3571,respectively.

parisontoAlternativeModelsforSNIa

IntheprevioussectionweshowedthatAbell496,Abell2199andAbell3571havesigni cantcentralabundanceenhancementswhicharecomprisedmostlyofSNIaejecta.AvarietyofabundanceratiosprovidemutuallyconsistentestimatesofthecentralSNIaironmassfraction,givenouradoptedmodelsfortheoreticalyieldsfromSNIaandII.ThismutualconsistencyencouragesustotestalternativetheoreticalmodelsforSNIa(alternativeSNIImodelswillbeexploredinWhite1999).Inparticular,wewillcomparetheW7“de agration”modeladoptedaboveto“delayeddetonation”modelswhichhavebeenexploredinresponsetoconcernsaboutthephysicalityoftheexplosionintheW7model(Khokhlov1991).Delayeddetonationmodelsarecharacterizedby(initially)slower amespeeds(afewpercentofthesoundspeed)thantheW7model.

WeconsiderthedelayeddetonationmodelsofNomotoetal.(1997b),whocalculateyieldsforasequenceofmodelsdistinguishedbyavarietyofdensitiesaheadofthede agrationfront,whichmodulatestheonsetofdetonation.We ndthattheelementalyieldsoftheirmodelsWDD1,WDD2andWDD3donotprovidethesameconsistency

We present constraints on theoretical models of Type Ia supernovae using spatially resolved ASCA X-ray spectroscopy of three galaxy clusters: Abell 496, Abell 2199 and Abell 3571. All three clusters have central iron abundance enhancements; an ensemble of

asfoundwithmodelW7inestimatingtheSNIa/IIfraction.Table6comparestheestimatesofSNIaironmassfractionsderivedfromthethreedelayeddetonationmodelsdescribedabove.TheadoptedSNIIyieldsareagainthoseofNomotoetal.(1997a,1997b).ComparisonofTables5and6showsthattheW7modelprovidesmoresatisfactoryresultsinthreedi erentways:1)moreabundanceratiosfallwithinthetheoreticalboundsofSNIaandSNII,astheyshould,whenW7isadopted(observedratioswhichareoutsidethetheoreticalboundsforSNIaandIIejecta,thereforepreventingmassfractionestimates,areindicatedbydashes);2)thedispersionintheaverageofthe(remaining)individualSNIaironmassfractionestimatestendstobesmallerwhentheW7modelisadopted;3)themutualconsistencyoftheSNIaironmassfractionestimatesderivedfromindividualabundanceratiosforagivenclusterisbestwhentheW7modelisadopted.

Concentratingonthenickelyieldinparticular,we ndthatourclusterobservationsfurtherdiscriminateagainstthedelayeddetonationmodelscitedabove.Theobservationallybestdeterminedabundanceratioinvolvingnickelisthenickeltoironratio.RecallfromTable4thattheindividualNi/FeratiosareconsistentwiththeotherindicatedratiosinestimatingthefractionalSNIacontamination.Figure2comparestheNi/FeratioobservedinthethreeclustersanalyzedinthisworktothepredictedNi/FeratiofromtheW7de agrationmodel,aswellasfromthethreedelayeddetonationmodelsdescribedabove;theindicatedobservationalerrorsarethepropagated90%con dencelimits.Evidently,theobservedNi/Feratiosareinconsistentwithanyofthesedelayeddetonationmodelsatbetterthan90%con dence.TheobservedNi/FeratioisfullyconsistentwiththeW7model,however.Thus,theelementalyieldsoftheW7modelaremoreconsistentwithX-rayspectroscopicobservationsofintraclustergasthanthoseofdelayeddetonationmodels.

6.Summary

TheintraclustergasinAbell2199,Abell3571andAbell496showsigni cantcentralmetalabundanceenhancements.InAbell2199theabundancedeclinesfrom0.49±0.04solaratthecenterto0.34±0.03solarintheouterparts(>3′).ThecentralabundanceenhancementinAbell3571isweaker,butstillsigni cant:theabundanceis0.37±0.06solaratthecenteranddeclinesto0.28±0.03solarbeyond3′.TheabundanceinAbell496declinesfrom0.53±0.04solarnearthecenterto0.36±0.03solarbeyond>3′(Dupke&White1999).

ThecentralregionsofAbell2199,Abell3571andAbell496aresigni cantlyenrichedbySNIaejecta.AvarietyofabundanceratioswereusedtoshowthattheSNIaironmassfractionsneartheircentersare74±7%,58±17%73±5%,respectively.

We present constraints on theoretical models of Type Ia supernovae using spatially resolved ASCA X-ray spectroscopy of three galaxy clusters: Abell 496, Abell 2199 and Abell 3571. All three clusters have central iron abundance enhancements; an ensemble of

TheNi/FeratiosobservedinallthreeclustersareinconsistentwiththepredictedvaluesfromtheNomotoetal.(1997b)delayeddetonationmodelsforSNIa,atgreaterthanthe90%con dencelevel.However,thepredictedNi/FeratiooftheupdatedW7de agrationmodel(Nomotoetal.1997b)isconsistentwiththeobservedvalues.TheseresultsillustratethepowerofX-rayclusterspectroscopytoconstraintheoreticalmodelsofsupernovae.ForthcomingobservationswithChandra,XMMandAstro-Eshouldprovidehigherqualityconstraintsusingtheseandadditionalabundanceratios.

ThisworkwaspartiallysupportedbytheNSFandtheStateofAlabamathroughEPSCoRgrantEHR-9108761.REWalsoacknowledgespartialsupportfromNASAgrantNAG5-2574.ThisresearchmadeuseoftheHEASARCASCAdatabaseandNED.WewouldliketothankDr.K.Arnaudforhelpfuldiscussions.

We present constraints on theoretical models of Type Ia supernovae using spatially resolved ASCA X-ray spectroscopy of three galaxy clusters: Abell 496, Abell 2199 and Abell 3571. All three clusters have central iron abundance enhancements; an ensemble of

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We present constraints on theoretical models of Type Ia supernovae using spatially resolved ASCA X-ray spectroscopy of three galaxy clusters: Abell 496, Abell 2199 and Abell 3571. All three clusters have central iron abundance enhancements; an ensemble of

FigureCaptions

Fig.1.—RadialdistributionsofoverallelementalabundancesinAbell496,Abell2199andAbell3571,insolarunits;theabundanceerrorsare90%con dencelimits;theradial“errors”indicatethesizeofthespectralextractionregions.

Fig.2.—ComparisonoftheNi/Feabundanceratiosintheinnerprojectedregions(0 2′)ofAbell496,Abell2199andAbell3571.Theoreticalpredictionsfordi erentSNIamodels,W7(thickline)anddelayeddetonationmodelsWDD1,WDD2andWDD3(thinlines),arealsoshown.

We present constraints on theoretical models of Type Ia supernovae using spatially resolved ASCA X-ray spectroscopy of three galaxy clusters: Abell 496, Abell 2199 and Abell 3571. All three clusters have central iron abundance enhancements; an ensemble of

Table1.E ectiveExposureTimes

SpectrometerExposureTime(ksec)

Abell496Abell2199Abell3571

We present constraints on theoretical models of Type Ia supernovae using spatially resolved ASCA X-ray spectroscopy of three galaxy clusters: Abell 496, Abell 2199 and Abell 3571. All three clusters have central iron abundance enhancements; an ensemble of

Table2.SpectralFitsa,b

ClusterRegionc

(arcmin)kT(keV)Abundance(solar)χ2ν

aErrorsare90%con dencelimits

ttingsofSIS0&1,GIS2&3bSimultaneous

cDistance

samefromtheX-raycenterasabovebutwithanextracooling ow

component

We present constraints on theoretical models of Type Ia supernovae using spatially resolved ASCA X-ray spectroscopy of three galaxy clusters: Abell 496, Abell 2199 and Abell 3571. All three clusters have central iron abundance enhancements; an ensemble of

Table3.IndividualElementalAbundancesfortheInnerRegions

Cluster

Abell2199aElementAbell496Abell3571

aErrorsare90%con dencelimits

We present constraints on theoretical models of Type Ia supernovae using spatially resolved ASCA X-ray spectroscopy of three galaxy clusters: Abell 496, Abell 2199 and Abell 3571. All three clusters have central iron abundance enhancements; an ensemble of

Table4.ElementalAbundanceRatiosa

Element

RatioCentralRegionAbell496Abell2199Abell3571SNIaTheorybW7WDD2SNIIaErrors

bSNarepropagated1σerrorsIa:Nomotoetal(1997a);SNII:Nomotoetal(1997b)

We present constraints on theoretical models of Type Ia supernovae using spatially resolved ASCA X-ray spectroscopy of three galaxy clusters: Abell 496, Abell 2199 and Abell 3571. All three clusters have central iron abundance enhancements; an ensemble of

Table5.FeMassFractionfromDi erentRatiosa

Element

RatioSNIaIronMassFractionAbell496Abell2199Abell3571

aErrors

bSNarepropagated1σerrorsIa:Nomotoetal(1997a);SNII:Nomotoet

al(1997b)

We present constraints on theoretical models of Type Ia supernovae using spatially resolved ASCA X-ray spectroscopy of three galaxy clusters: Abell 496, Abell 2199 and Abell 3571. All three clusters have central iron abundance enhancements; an ensemble of

Table6.IronMassFractionfromDi erentDelayedDetonationModelsa

ClusterElement

RatioSNIaIronMassFractionbWDD1WDD2WDD3

A2199

′′

′′

′′

′′

′′O/FeSi/FeNi/FeO/SiSi/NiWA.180.72+0 0.21——≤0.83—.180.72+0 0.21.220.66+0 0.21.100.93+0 0.10—≤0.86—0.88±0.09.220.62+0 0.22.100.78+0 0.09—≤0.89≥0.960.75±0.09

aErrors

bSNarepropagated1σerrorsIa:Nomotoetal(1997a);SNII:Nomotoetal

(1997b)

cWeightedAverage

We present constraints on theoretical models of Type Ia supernovae using spatially resolved ASCA X-ray spectroscopy of three galaxy clusters: Abell 496, Abell 2199 and Abell 3571. All three clusters have central iron abundance enhancements; an ensemble of

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