X-Ray Spectral Study of the Extended Emission, ‘the Cap’, Located 11.6 kpc above the Disk of M82

[摘要] TheextendedX-rayemissionfrom‘theCap’region,located$$11{}^{prime}$$(11.6 kpc)abovethediskofthestarburstgalaxyM82,hasbeenobservedwithSuzakuandXMM-Newton.OwingtothegoodenergyresolutionandthelargecollectingareaoftheXISonSuzaku,combinedwithsimilarpropertiesoftheEPICinstrumentonXMM-Newton,wehaveclearlydetectedK-shellemissionlinesfromOVII,OVIII,NeX,MgXI,MgXII,SrXIII,andtheFeLcomplex.TwoopticallythinthermalplasmacomponentsarerequiredtofittheobservedX-rayspectra.WehavedeterminedthemetalabundancesofO,Ne,Mg,Si,andFeinthisregionforthefirsttime.Theirmetalabundanceratiosagreewellwiththoseofmetal-poorstarsandthemodelpredictionofmetalssynthesizedbytype-IIsupernovae,buttheyarenotconsistentwiththemetallicitiesoftype-Iasupernovae.ThisresultissupportfortheideathattheoriginofthemetalsintheCapistype-IIsupernovaexplosionsoccurringinthestarburstregionsintheM82galaxy.WediscussthepossiblecontributionfromsputtereddustgrainstothemetalsintheCap.AnemissionlineconsistentwiththeCVItransitionof$$n=4$$to1at0.459 keVhasbeenmarginallydetected,althoughitisnotstatisticallysignificantatthe99%confidencelevel;thepresenceofthislinewouldsuggestcharge-exchangeprocessesintheCap.

[学科分类] 天文学(综合)

[关键词] "galaxies: abundances";"galaxies: individual (M 82)";"galaxies: jets";"galaxies: starburst";"X-rays: galaxies"