Hydrodynamical simulations of the jet in the symbiotic star(6)

In papers I and II in this series, we presented hydrodynamical simulations of jet models with parameters representative of the symbiotic system MWC 560. These were simulations of a pulsed, initially underdense jet in a high density ambient medium. Since th

6

Fig.7.—sameasFig.

6,butformodeliv’

Fig.8.—Spectrumintheenergyrangebetween0.15–15keVformodelveryusingdi erenti’ondaystwocomponentsionization155;severalatpotentialsstrongemissiondi erenttemperatures.

whichcanlinesonlyarebepresentexplainedwith4.3.Emissionlinesinthemodelspectra

Wehaveidenti edthestrongestemissionlineschar-acterizingatypicaljetspectrumusingthespectrumde-rivedfrommodeli’onday155asatemplate(Fig.8).Themostprominentlinesaretheoxygenlineat0.57keV,theNelinesat0.93and1.03keV,theMglinesat1.35and1.47keV,theSilinesat1.86,2.01and2.18keV,andtheFecomplexatabout6.5keV.Allstronglineswiththeiridenti cationsaregiveninTable2,in-cludingtheir uxesatdays153and155inmodeli’anddays105and107inmodeliv’.MostoftheselinesarehydrogenicorHe-likelinesofheavyelements,however,alsolinesofhigherionizationstatesarepresent(FeXXII,FeXXIII,FeXXV).Thusthissetoflineswithverydif-ferentionizationpotentialscanalsoonlyexplainedwithtwocomponentsatdi erenttemperatures.

5.THEX-RAYEMISSIONMAPS

Theresultsintheprevioussectionsuggesttheexis-tenceoftwocomponents,awarmonewithtemperaturesintherangeof(1.6–3.8)×106Kandahotonewithtemperaturesof(8–17)×106K,respectively.AsalreadypointedoutinPaperIandII,thejetconsistsofdense,coolknotsandtenuous,hotinter-knotgas.TheknotsaretoocoldtoemitX-rays,thusthelowandhighenergycomponentsintheX-rayspectrumprobethetempera-turestructureofthehotpartsofthejet(Fig.1andFig.12inpaperI).Thesehotpartsconsistofshockedmate-rialintheinter-knotgassegments.Temperaturegradi-

entsarepresentwithineachinter-knotgassegmentandalsobetweentheinter-knotgasclosetothejetsourceandthosedownstreamnearthejethead.Theregionswiththehighesttemperaturesandthusemissionabove6keVlieinthe rsttwointer-knotgassegmentswithinonlyafewAUfromthecentralsource(Fig.9).Theinter-knotgassegmentsbecomeprogressivelycooler,astheymovefartherawayfromthejetsourceduetoadiabaticexpansionandtheresultingcoolingofjetmaterial.

PARISONWITHOBSERVATIONS

WenowcomparetheresultsofourmodelstoX-rayobservationsofthethreeobjectsMWC560(onlyupperlimitstothe uxareavailable),CHCygandRAqr.

6.1.MWC560

Thesource uxesinthe0.2–2.4keVrangeare3×10 13ergs 1cm 2formodeli’and2×10 12ergs 1cm 2formodeliv’,usingadistanceof2.5kpctoMWC560(Schmidetal.2001,andreferencestherein).The 13latter uxisreducedtoanabsorbed uxof1.7×10ergs 1cm 2,usingthemodelofthevisualinterstellarextinctionintheGalaxybyHakkilaetal.(1997) 2whichgivesanAforMWC560.Thev=0.88orNabsorbed uxisH=1.55×1021cmconsistentwithMWC560’snon-detectionintheROSATall-skysurvey(<7×10 13ergs 1cm 2,M¨ursetetal.1997).The uxes,however,arehighenoughsuchthattoday’sX-raytelescopeasChandraandXMM-NewtonshouldbeabletodetectMWC5602.

6.2.CHCyg

SincethejetvelocitiesaresimilarinMWC560andCHCyg,wecanmakeadetailedcomparisonofourmodelswiththelatterobject.ThiscomparisonislimitedtothesoftemissionfromthepropagatingjetandexcludestheX-rayemissionaboveabout2keVwhichisbelievedtobedominatedbythevariablescatteredhardX-raysfromthecentralsource.

Ezukaetal.(1998)resolvedforthe rsttimeatomicemissionlines(ortheirblends)fromelementsinhydro-genicandHe-likeionizationstatesintheX-rayspectraofCHCyg.Themostprominentfeaturesintheobservedspectraaretheoxygenlineat0.57keV,theblendofi)Nelinesat0.93and1.03keV,ii)Mglinesat1.35and1.47keV,iii)Silinesat1.86,2.01and2.18keV,andtheFelinecomplexatabout6.5keV.Theselinesarealsoseeninourmodelspectra.Furthermore,theyalsohadtointroduceatwo-temperaturethermalplasmamodeltoexplainthesetoflinesdetectedintheASCAspec-trum.Thetemperaturesoftheirtwocomponents(0.21and0.72keV)areinthesamerangeasinourmodeli’(warmcomponent:0.14–0.26keV,hotcomponent:0.69–1.5keV,see§4.2).Inmodeliv’,thewarmcomponentistoohot(0.26–0.33keV)toexplaintheobservations.Recently,KCR07reportedthedetectionofmultiplecomponents,includinganarc,inthearchivalChandraimages.ThisarchasasimilaropeningangletomanyofthearcsvisibleinourX-rayemissionmaps(Fig.9),anditspresencesupportsourpulsed-jetmodelinwhich

2

executedXMM-NewtoninAO-6afterobservationsMay2007.

proposedbytheauthorswillbe