TheGalac)ccenterasadarkma1ergamma‐raysource

Cesarinietal.

Astropar)clePhysics21(2004)267‐285

EGRETANDGLAST

•  EGRET,theEnerge)cGamma‐RayExperimentTelescopeonCGRO(Comptongammarayobservatory):

‐>Detectedgammaraysinthe20MeV‐30GeVrange.

‐>Theangularresolu)onwasstronglyenergydependent,witha67%confinementangleof5.5°at100MeV,fallingto0.5°at5GeVonaxis

‐>Brightgamma‐raysourcescanbelocalizedwithapproximately10'accuracy.

•  Gamma‐rayLargeAreaSpaceTelescope(GLAST)isscheduledforMay16,2008

‐>Observeatenergiesfrom8keVto300GeV ‐>Op)calfieldofviewover2steredians. ‐>Measureloca)onsofbrightsources

within1'accuracy.

EGRETALLSKYMAPVS.SIMULATEDGLASTALLSKYMAP

Mo)va)on

•  TheEGRETtelescopehasmappedtheγ‐rayskyuptoanenergyofabout20GeVoveraperiodof5yrs.

•  Thedetectedfluxlargelyexceedsthediffuseγ‐raycomponentexpectedintheGCdirec)onwithin1.5°oftheGC(l=b=0°)

•  Comparewithastandardmodelingoftheinterac)onofprimarycosmicrayswiththeinterstellarmedium

•  EGRETGeVexcessshows,asbasicfeatures,thekindofdistor)onofthediffuseγ‐rayspectrumonewouldexpectfromaWIMP‐inducedcomponent,assumingthatthedarkma1erhaloprofileispeakedtowardtheGC.

WHYISWIMPANNIHILATIONIMPORTANT

• IthaslongbeenarguedthatifaSMBHexistsatthegalac)ccenter,theprocessofadiaba)caccre)onofdarkma1eronitwouldproducea“spike”inthedarkma1erdensityprofile.• Dominantneutralinoannihila)onchannelsincludeannihila)ontofermions,gaugebosons,higgsbosons,andalsotophotons.• Fragmenta)onordecayoftree‐levelannihila)onstatesgiverisetophotons.

Totalfluxassuperposi)onoftwocontribu)ons

•  Componentduetointerac)onofprimarycosmicrayswithinterstellarmedium(backgroundcontribu)onwithspectralshapedefinedbySb(Eγ)(backgroundcontribu)on)

•  ComponentduetoWIMPannihila)oninthedarkma1erhalo,whoseenergyspectrumisdefinedbySχ(Eγ)

•  NbandNχaredimensionlessnormaliza)onparameters.

Backgroundcomponent

•  Produc)onanddecayofΠos,inverseComptonsca1eringandbremsstrahlung

•  ForEγ>1GeV,thedominantbackgroundsourceisgivenbyΠodecays.

SignalComponent

Toymodel

Simula)onfromGLAST

GLASTsimula)onsaccordingtoNFWandMooreetal.models

•  IsfluxcomingfrompointsourcelocatedatGCorfromadiffusesource?

•  NFWandMooreetal.predictanenhancementindarkma1erdistribu)ontowardsGC.

•  r0=8.5kpc,ρ0=0.3Gev/cm3,γ=1.54•  rmin=10‐5kpc

ANGULARSIGNATUREOFWIMPFROMGLASTSIMULATION

GLASTperformanceforaweakersource

THELIGHTESTNEUTRALINOINMSUGRAFRAMEWORK