probing the geometry and physics of the emission region in active galactic nuclei using hard x-ray amp; gamma-ray observations

《probing the geometry and physics of the emission region in active galactic nuclei using hard x-ray amp; gamma-ray observations》由会员上传分享，免费在线阅读，更多相关内容在教育资源-天天文库。

1、ProbingtheGeometryandPhysicsoftheEmissionRegioninActiveGalacticNucleiusinghardX-rayandGamma-rayobservationsNatashaL.WoodsOfficeofScience,ScienceUndergraduateLaboratoryInternship(SULI)TheUniversityofTexasatDallasStanfordLinearAcceleratorCenterMenloPark,CAAugust14,20

2、09PreparedinpartialfulfillmentoftherequirementsoftheOfficeofScience,DepartmentofEnergy'sScienceUndergraduateLaboratoryInternshipunderthedirectionofMarcoAjelloandMasaakiHayashidaattheKavliInstituteforParticleAstrophysicsandCosmology,StanfordLinearacceleratorCenter.P

3、articipant:_____________________________________SignatureResearchAdvisers:___________________________________Signature__________________________________Signature1.INTRODUCTIONThestudyofActiveGalacticNuclei(AGN)beganasearlyas1908whenArthurFathnoticedsixemissionlines

4、inthespectraofNGC1068thatcouldnotbeattributedtoanystellarprocesses.LessthantwodecadesthereafterCarlSeyfertrecognizedsimilaremissionlinesinthespectraofspiralgalaxies(Fig.1).OvertimegalaxieswiththeseemissionlineswerenamedAGN.Theseobjectsarecharacterizedbythefactthatt

5、hemajorityoftheirenergyoutputareunrelatedtostellarprocesses.Formally,AGNarecompactregionsofspaceatthecenterofgalaxiesthatareexceedinglyluminousoverallorpartoftheelectromagneticspectrum[1].Figure1:RepresentativespectraofdifferenttypesofAGN,notethattheSeyfert1spectra

6、havenoticeablybroaderemissionlinesthantheSeyfert2spectra,imagefromRichmond[14].1.1AGNClassificationAGNareclassifiedbytheirradioluminosityandspectralproperties.Radio-loudAGNemitradiowaves,radio-quiethaveminimalornoradioflux.Additionally,ifthesourcehasabrightopticalc

7、ontinuumwithbroademissionlinesitisclassifiedasType1.SourcesthathaveaweakopticalcontinuumandnarrowemissionlinesaredescribedasType2(Fig.1)[2].1.2UnifiedModelofAGNTheUnifiedModelofAGNpositsthatallAGNarethesame.andtheperceiveddifferencescanbeattributedtotheviewingorien

8、tationofAGN.InthismodelallAGNareaxissymmetricandconsistofa106-10M⊙super-massiveblackhole(SMBH)thatactivelyaccretesmatterfromadiskaroundit.Outside