08.06.1;08.14.1;09.09.1RCW86;09.19.2;13.25.5
AnunresolvedX-raysourceinsidethesupernovaremnantRCW86
JaccoVink,FabrizioBocchino,FrancescoDamiani,andJelleS.Kaastra
AstrophysikalischesInstitutPotsdam,AnderSternwarte16,D-14482Potsdam,Germany
AstrophysicsDivision,SpaceScienceDepartmentofESA,ESTECPostbus299,2200AGNoordwijk,TheNetherlandsOsservatorioAstronomicodiPalermo,PiazzadelParlemento1,I-90134Palermo,Italy
SRON,LaboratoryforSpaceResearch,Sorbonnelaan2,NL-3584CAUtrecht,TheNetherlands
Received/Accepted
Abstract.WereportonthediscoveryofanunresolvedX-raysourceinsidethesupernovaremnantG315.4-2.3(RCW86).Thesourceislocated7totheSouthwestofthegeometricalcentreandmaybeclosetotheactualexplosioncentreofthesupernova,whichmakesthisacandidateforthestellarremnantassociatedwithRCW86.However,thepresenceofapossible
opticalcounterpartwith
at3fromtheX-raypositionandevidenceforlongtermvariabilitymeansthatthesourceisprobablyanactivestar.AbetterX-raypositionandbetterX-rayspectroscopyalongwithanidentificationoftheopticalsourceareneededtoexcludetheX-raysourceasaneutronstarcandidate.
Keywords:Stars:flare–Stars:neutron–ISM:individualobjects:RCW86–ISM:supernovaremnants–X-rays:Stars
Sendoffprintrequeststo:J.Vink(jvink@aip.de)
Table1.AsummaryofROSATandEinsteinobservationswhichcoverthepointsource.Datesrefertothestartdateoftheobservation.
4/2/1980h1437s62SWEinsteinHRI87564/9/1992rp500078n00NEROSATPSPC32122/2/1993rp500079n00SWROSATPSPC45673/2/1993rp500078a01NEROSATPSPC222418/8/1993rp500078a02NEROSATPSPC45092/9/1994rh500077a01SWROSATHRI24474/8/1995rh500077a02SWROSATHRI6034
2JaccoVinketal.:AnunresolvedX-raysourceinsidethesupernovaremnantRCW86
05:0010:0015:0020:0025:0030:0035:00-62:40:0045:0046:0044:0042:0014:40:00Fig.1.RCW86asobservedbythePSPC(SWpointing).Thecircleindicatesthepositionofthepointsource.
Table2.Bestfitpositionsandcountratesofthepointsource.ThefirstthreerowslisttheresultofmaximumlikelihoodfitstotheROSATandEinsteinHRIdata.Thestatistichasadistributionwiththreedegreesoffreedom.Positionerrorsdonotincludesystematic
errorsandcorrespond
(90%confidenceregions).ThePSPCpositionsandcountrateswereestimatedwithawaveletanalysismethod(Damianietal.1997)usingtheenergychannels20-200(keV).
h1437s62144151.52-623613.12.60.4
28.6rh500077a01144151.64-623611.93.512.4rh500077a02144151.11-623613.21.955.3
rp500078n00144153.3-62363765rp500079n00144151.4-6236815rp500078a01144149.0-62355259rp500078a02144148.9-62362239
1
TheblackbodymodelinSPEXv1.10containsasmallbugwhichwefixedforthisanalysis.ThethinthermalplasmaorCIE(collisionalionizationequilibration)modelissimilartothemekalmodelinxspec.
JaccoVinketal.:AnunresolvedX-raysourceinsidethesupernovaremnantRCW863
Table3.ResultsofthespectralfitstothePSPCdata.Theluminositiesarenormalisedtoadistanceof1kpc.Foreachmodelthespectrumwasfittedwithcmandwithasafreeparameter.Errorrangescorrespondto,or90%confidencelimits.
BlackbodyPowerLawhotthinplasma
(mekal)idem,
kk
keVkeV
cmcm
1.7
3.61.616.95.11.91.3
8.4/91.1/84.1/91.7/814.7/94.3/810.5/91.0/8
ph/s/keV@1keVph/s/keV@1keV
1.7
kk
keVkeVkeVkeV
cmcmcmcm
1.7
kk
1.7
3.01.9
4JaccoVinketal.:AnunresolvedX-raysourceinsidethesupernovaremnantRCW86
materialshouldbeconsideredasanalternativemodel(Umedaetal.2000,Chakrabartyetal.2000).ThesoftnessoftheX-rayspectrumisapropertysharedwiththeunresolvedsourcesinPuppisA,G296.5+10.0andAXPs(Mereghettietal.1996).Itslongtermvariabilityismoreinlinewiththebehaviourofanactivestar,butawellestablishedneutronstarcandidatelikethepointsourceinRCW103isalsovariableonsimilartimescales(Gotthelfetal.1999).
ThepositionoftheX-raysourceisroughlyatanan-gulardistanceof7fromthegeometricalcenterofthesu-pernovaremnant.Thiscorrespondstoatransversevelocity1200km/s,ifthesupernovaremnantisatadistanceof2.5kpcand5000yrold,orifthedistanceis1kpcandanageof1800yr.Suchakickvelocityisratherhigh,butstillconsistentwithobservationsofotherneutronstars(Lyne&Lorimer1994).Note,however,thattheremnantisfarfromcircularlysymmetric,andthecontrastinemissionbetweentheNortheastandSouthwestoftheremnant(seee.g.Vinketal.1997,Bocchinoetal.2000)suggeststhatintheSouth-westtheshockwaveisencounteringadensermedium,whichcouldmeanthattheactualexplosioncenterwasmoretotheSouthwestofthegeometricalcenterandclosertotheunre-solvedsource.Interestingly,theremnantisquitesymmetricintheNortheast/SouthwestdirectionandtheX-raysourceisroughlylocatedontheaxisofsymmetry.Thepositionofthepointsourceisoneofitssalientproperties.Thewaveletde-tectioncodehasalsodetectedanothersignificantpointsourceinsidetheremnant,7fromtheNorthernshellwithcoordinates
14h43m47.0sand-621929.Thesourceseemsem-beddedinasmall1sizeextendedstructure.However,spectralanalysisofthissourcerulesoutmodelswithnon-thermalorblack-bodyradiationandthespectrumisconsistentwithther-malX-rayemission,characteristicfortheNorthrimasreportedbyBocchinoetal.(2000).Thissuggeststhatthisasmallfrag-mentoftheshellseeninprojection.
ItseemsunlikelythattheunresolvedX-raysourceismuchfurtherawaythanRCW86,astheX-rayabsorptioncolumnistoolowforadistantsourcenearthegalacticplane.ThismeansthatitisunlikelythatitiseitheranAGNoranX-raybinary.ForthesourcetobeatypicalX-raybinarywithaluminosityof
erg/s,itshouldbeatadistanceof300kpc.Thisis
incompatiblewithboththeX-rayabsorptionandwiththesizeofourgalaxy.
Themainargumentagainstanunambiguousidentificationofthesourcewithastellarremnantisthepresenceofacan-didateopticalcounterpart.TheUSNO-A2.0catalogue(Monetetal.1998)containsonesourceatanangulardistanceof3totheunresolvedX-raysource(seeFig.2).Thestarhasmag-nitudesand,whichsuggestaK-star,al-thoughthemagnitudeerrorsandtheunknownextinctionmakealatetypeG-staroraearlytypeMstaralsopossible(Zombeck
,1990).ThetypicalVmagnitudeofthisstarwouldbe
which,foramainsequencestar,impliesadistanceofpc.ForthisdistancetheX-rayluminosityoftheX-raysourceis
.ThisisconsistentwiththeX-rayluminosityof
abrightactivestar(seee.g.Zombeck1990p.88,Agrawalet
al.1986).ThepossibilitythatthisisjustachancealignmentcanbeestimatedusingtheUSNO-A2.0catalogue.Thereareabout0.0015starspersquarearcsecwithinthefieldaroundtheX-raysource,whichmeansthatthechancetofindabrightstarwithinthe95%errorcircle(seeFig.2)is11%.
TheevidenceforlongtermvariabilityandthepresenceofalatetypestarclosetotheX-raypositionfavourtheidentifica-tionoftheX-raysourcewithanactivestar,ratherthanwiththestellarremnantassociatedwithRCW86.However,tofirmlyestablishthisidentification,opticalspectroscopyofthepos-sibleopticalcounterpartandX-rayobservationswithabetterpositionalaccuracyofthesourceareneeded.ImprovedX-rayspectroscopicdatacanalsobeusedtodistinguishbetweenthetypicalopticallythinthermalspectrumofanactivestarandthefeaturelessspectrumofaneutronstar.
Acknowledgements.WethankGuentherHasingerandRickHarn-denfortheirinformationregardingthesystematicpositionerrorsofROSATandEinstein.WethankRichardStromandJohnDickelfordiscussionsontheradiomapofRCW86/G315.4-2.3.
References
AgrawalP.C.,RaoA.R.,SreekantanB.V.,1986,MNRAS219,225BocchinoF.,VinkJ.,FavataF.,etal.,2000,acceptedbyA&ABuccheriR.,BennetK.,BignamiG.F.,etal.,1983,A&A128,245CashW.,1979,ApJ228,939
ChakrabartyD.,PivovaroffM.J.,HernquistL.E.,etal.,2000,astro-ph/0001026
Chin,Y.-N.,HuangY.-L.,1994,Nat371,398
ClarkD.H.,StephensonF.R.,“TheHistoricalSupernovae”,1977,
PergamonPressLtdOxford
DamianiF.,MaggioA.,MicelaG.,SciortinoS.,1997,ApJ483,350DickelJ.,etal.,2000,inpreparation
GotthelfE.V.,PetreR.,VasishtG.,1999,ApJ514,L107
HasingerG.,TurnerT.J.,GeorgeI.M.,etal.,1992,Legacy2,77HasingerG.,JohnstonH.M,VerbuntF.,1994,A&A288,466
HelfandD.,1998,in“Therelationshipbetweenneutronstarsandsu-pernovaremnants”,eds.Bandieraetal.,JournaloftheItalianAs-tron.Soc.69/4,791
KaastraJ.S,MeweR.,NieuwenhuijzenH.,1996,In:Watanabe,T.
(ed.)The11colloquiumonUVandX-raySpectroscopyofAs-trophysicalandLaboratoryPlasmas,p.411Lyne,A.G.,Lorimer,D.R.,1994,Nat369,127
MereghettiS.,BignamiG.F.,CaraveoP.A.,1996,ApJ464,842
MereghettiS.,1998,in“Therelationshipbetweenneutronstarsand
supernovaremnants”,eds.Bandieraetal.,JournaloftheItalianAstron.Soc.69/4,810
MonetD.,etal.,1998,USNO-A2.0:AcatalogueofAstrometricStan-dards,http://www.nofs.navy.mil
PetreR.,BeckerC.M.,Winkler,P.F.,1996,ApJ465,L43
RosadoM.,Ambrocio-CruzP.,LeCoarerE.,MarcelinM.,1996,
A&A315,243
StromR.G.,1994,MNRAS268,L5TananbaumH.,1999,IAUcircular7246
UmedaH.,NomotoK.,TsurutaS.,etal.,2000,ApJ534,L193
vanSpeybroeckL.,EpsteinA.,FormanW,etal.,1979,ApJ234,L49VinkJ.,KaastraJ.S,BleekerJ.A.M.,1997,A&A328,628WesterlundB.E.,1969,AJ74,879
ZombeckM.V.,1990,HandbookofSpaceAstronomy&Astro-physics,2nded.(Cambridge,UK,CambridgeUniversityPress)
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