PL8:Astro-ParticlePhysics
GeorgG.Raffelt(raffelt@mppmu.mpg.de)
Max-Planck-Institutf¨urPhysik(Werner-Heisenberg-Institut)F¨ohringerRing6,80805M¨unchen,Germany
Abstract.Recentdevelopmentsofthoseareasofastro-particlephysicsaredis-cussedthatwererepresentedattheHEP97conference.Inparticular,thecurrentstatusofdirectandindirectdark-mattersearchesandofTeVneutrinoandγ-rayastronomywillbereviewed.
1Introduction
Astro-particlephysicsissuchawidefieldthatitiscertainlyimpossibletoreviewitscurrentstatusinasinglelecture.Tomakeasensibleselectionitseemedmostappropriatetocoverthoseareaswhichwererepresentedintheparallelsessionsofthisconference,i.e.mostlyexperimentaltopicsinthear-easofdark-matterdetectionandofneutrinoandγ-rayastronomy.Oneofthemostcherisheddark-mattercandidatesisthelightestsupersymmetricparticlesothatacceleratorsearchesforsupersymmetryareofimmediatecosmologicalimportance,yetIconsiderthistopictolieoutsideofmyassignment.Like-wisethelaboratorysearchesforneutrinomassesandoscillationsareofdirectastrophysicalandcosmologicalsignificance,yettheyexceedtheboundariesofmytask.Finally,IwillnotcovertheveryexcitingrecentdevelopmentsinMeVtoGeVneutrinoastronomy(solar,supernova,andatmosphericneutri-nos)becausetheyarereviewedbyanotherspeaker[1].
2
DarkMatterSearches
2.1
DarkStars(MACHOs)
Theexistenceofhugeamountsofdarkmatterintheuniverseisnowes-tablishedbeyondanyreasonabledoubt,butitsphysicalnatureremainsanunresolvedmystery[2,3].Anumberofwell-knownargumentsnegatethepos-sibilityofapurelybaryonicuniverse,butalsopointtosignificantamountsofnonluminousbaryons.Ifsomeofthemareinthegalactichaloonemostnatu-rallyexpectsthemtobeintheformofMassiveAstrophysicalCompactHaloObjects(MACHOs)—smallandthusdimstars(browndwarfs,M-dwarfs)orstellarremnants(whitedwarfs,neutronstars,blackholes).StellarremnantsandM-dwarfsarevirtuallyexcluded[4],whichleavesuswithbrowndwarfs,i.e.normalstarswithamassbelow0.08M⊙(solarmasses)sothattheyaretoosmalltoignitehydrogen.
2G.G.RaffeltPaczy´nskiproposedin1986tosearchfordimstarsbythe“microlensing”technique[5].Adistantstarbrightenswithacharacteristiclightcurveifagravitationaldeflectorpassesnearthelineofsight.Gravitationallensingproducestwoimages,butiftheirangularseparationistoosmalltheonlyobservableeffectistheapparentbrighteningofthesource.AconvenientsampleoftargetstarsisprovidedbytheLargeMagellanicCloud(LMC),asatellitegalaxyoftheMilkyWay.TheLMChasenoughbrightstarsanditisfarenoughawayandfarenoughabovethegalacticplanethatoneintersectsagoodfractionofthegalactichalo.IfMACHOscomprisethehalo,thelensingprobability(“opticaldepth”formicrolensing)isabout10−6sothatonehastomonitor∼106starsintheLMC.Thedurationofthebrightnessexcursiondependsonthelensmass;for1M⊙itistypically3months,for10−2M⊙itis9days,for10−4M⊙itis1day,andfor10−6M⊙itis2hours.ThemicrolensingsearchwastakenupbytheMACHOandtheEROSCollaborations,bothreportingcandidatestowardtheLMCsince1993[6].Moreover,thegalacticbulgehasbeenusedasanothertargetwheremanymoreeventsoccurthroughmicrolensingbyordinarydiskstars.Whiletheseobservationsarenotsensitivetohalodarkmatter,theyallowonetodevelop
Fig.1.Exclusiondiagramat95%C.L.forthehalofractionandmassoftheassumedMACHOs[7].Theirmassesweretakentobefixedandastandardmodelforthegalactichalowasused.ThedottedlineontheleftistheEROSlimitwhenblendingandfinitesizeeffectsareignored.Thedot-dashedanddottedlinesontherightaretheEROSlimitswhen1or2oftheireventsareattributedtoMACHOs.Thecrossiscenteredonthe95%C.L.permittedrangeoftheMACHOCollaboration[8].
PL8:Astro-ParticlePhysics3
agoodunderstandingofthemicrolensingtechniqueandareaninterestingmethodtostudythegalaxyanditsstellarcontent.Withinthepastfewyearsmicrolensinghasestablisheditselfasacompletelynewapproachtoastronomy,withatleasthalfadozencollaborationspursuingobservationsofvarioustargetregions.Theyalsoproduceahugedatabaseofintrinsicallyvariablestars,whichisaninvaluableprojectinitsownright.
Farfromclarifyingthestatusofdimstarsasagalacticdarkmattercontribution,themicrolensingresultstowardtheLMCwithaboutadozenevents[7,8]arequiteconfusing.Forastandardsphericalhalotheabsenceofshort-durationeventsexcludesalargerangeofMACHOmassesasadomi-nantcomponent(Fig.1).Ontheotherhand,theobservedeventsindicateahalofractionbetweenabout10%and100%ofMACHOswithmassesaround0.4M⊙(Fig.1).Thisischaracteristicofwhitedwarfs,butagalactichaloconsistingprimarilyofwhitedwarfsishighlyimplausibleandalmostex-cluded[4].Attributingtheeventstobrowndwarfs(M<∼0.08M⊙)requiresaverynonstandarddensityand/orvelocitydistribution.OtherexplanationsincludeanunexpectedlylargecontributionfromLMCstars,athickgalacticdisk,anunrecognizedpopulationofnormalstarsbetweenusandtheLMC,andotherspeculations[9].Itisquiteunclearwhichsortofobjectsthemi-crolensingexperimentsareseeingandwherethelensesare.
MeanwhileafirstcandidatehasappearedinboththeMACHOandEROSdatatowardtheSmallMagellanicCloud(SMC)[10]whichisslightlymoredistantthantheLMCandabout20◦awayinthesky.Oneeventdoesnotcarrymuchstatisticalsignificance,butitsappearanceisconsistentwiththeLMCdataiftheyareinterpretedasevidenceforhalodarkmatter.However,thisinterpretationwouldimplyafewsolarmassesfortheSMClensduetothelargeduration.
BesidesmoredatafromtheLMCandSMCdirections,otherlinesofsightwouldbeinvaluable.OfparticularsignificanceistheAndromedagalaxyasatargetbecausethelineofsightcutsthroughthehaloalmostverticallyrelativetothegalacticdisk.Unfortunately,Andromedaissofarawaythatonecannotresolveindividualtargetstars.Onedependsonthe“pixellensing”techniquewhereonemeasuresthebrighteningofasinglepixeloftheCCDcamera;onepixelcoverstheunresolvedimagesofmanystars.Atleasttwogroupspursuethisapproachwhichhasproducedfirstlimits[11].2.2
Axions
WhilethemicrolensingsearchesseemtoindicatethatsomefractionofthegalactichalomayconsistofMACHOs,perhapsevenintheformofpri-mordialblackholes[12],particledarkmatteraficionadosshouldnotgetdisheartened—weaklyinteractingparticlesarestillthebestmotivatedop-tionforthecolddarkmatterwhichapparentlydominatestheuniverse.
OneoftwowellmotivatedpossibilitiesareaxionswhichappearasNambu-GoldstonebosonsofthespontaneouslybrokenPeccei-Quinnsymmetrywhich
4G.G.Raffelt
ismotivatedasasolutionoftheCPproblemofstronginteractions[13].Apartfromnumericalparametersoforderunity,thesemodelsarecharacterizedbyasingleunknownquantity,thePeccei-Quinnscalefaortheaxionmassma=0.62eV(107GeV/fa).Intheearlyuniverseaxionsformnonthermallyashighlyoccupiedandthusquasi-classicallow-momentumoscillationsoftheaxionfield.Ifaxionsarethedarkmatter,abroadclassofearly-universescenariospredictsmatolieintherange1µeVto1meV[14].
InamagneticfieldaxionsconvertintophotonsbythePrimakoffpro-cessbecausetheyhaveatwo-photoncoupling[15].Afrequencyof1GHzcorrespondsto4µeV;asearchexperimentforgalacticaxionsconsistsofahigh-Qmicrowaveresonatorplacedinastrongmagneticfield.Atlowtem-peratureonelooksfortheappearanceofmicrowavepowerbeyondthermalandamplifiernoise.Twopilotexperiments[16,17]couldnotreachrealisticaxionmodels,buttwoongoingexperimentswithmuchlargercavityvolumeshavetherequisitesensitivity(Fig.2).Initscurrentsetup,theLivermoreexperiment[18]usesconventionalmicrowaveamplifierswhiletheKyotoex-periment[19]employsacompletelynoveldetectiontechniquebasedontheexcitationofabeamofRydbergatomswhichpassesthroughthecavity.
Fig.2.CurrentlimitsongalacticdarkmatteraxionsfromtheUniversityofFlorida(UF)[16]andtheRochester-Brookhaven-Fermilab(RBF)[17]experimentsandsearchgoalsoftheLivermore[18]andKyoto[19]experiments.Itwasassumedthatthelocalgalacticaxiondensityis300MeVcm−3.Theaxion-photoncouplingisgivenbyLint=gaγE·Ba.TherelationshipbetweengaγandmaforthepopularDFSZandKSVZmodelsisindicated.
PL8:Astro-ParticlePhysics5
2.3WeaklyInteractingMassiveParticles(WIMPs)
TheotherfavoredclassofparticledarkmattercandidatesareWIMPs,no-tablythelightestsupersymmetricparticlesintheformofneutralinos[20].DirectsearchesrelyonWIMP-nucleusscattering,forexampleinGeorNaIcrystals[21].Theexpectedcountingrateisoforder1eventkg−1day−1andthusextremelysmall.Tobeatcosmic-rayandradioactivebackgroundsonemustgodeeplyundergroundanduseultrapurematerials.Therecoilsfor10–100GeVWIMPmassesareoforder10keV.Suchsmallenergydepositionscanbemeasuredbyelectronic,bolometric,andscintillationtechniques.Thenumberofexperimentalprojectsistoolargetoevenlistthemhere[22].
Thecurrentlimitsalreadydigintothesupersymmetricparameterspace(Fig.3).TheDAMA/NaIexperimenthasactuallyreportedaWIMPsigna-ture[30]whichwouldpointtoneutralinosjustbelowtheirpreviousexclusionrange[31].Thesignificanceofthisresultisverylow,andtentativesignalsareboundtoappearjustbelowthepreviousexclusionrange.Still,thegoodnewsisthatthisdetectioncouldbetrueinthesensethatonehasreachedthesensitivitynecessarytofindsupersymmetricdarkmatter.Inthenearfuturethelarge-scalecryogenicdetectorsCRESST[28]andCDMS[29]willexploreavastspaceofWIMP-nucleoncross-sections(Fig.3).
Fig.3.Exclusionrangeforthespin-independentWIMPscatteringcrosssectionpernucleonfromtheNaIexperiments[23,24]andthegermaniumdetectors[25].Alsoshownistherangeofexpectedcountingratesfordark-matterneutralinosintheminimalsupersymmetricstandardmodel(MSSM)withoutuniversalscalarmassunification[26,27].Thesearchgoalsfortheupcominglarge-scalecryogenicexperimentsCRESST[28]andCDMS[29]arealsoshown,whereCDMSislocatedatashallowsiteatStanford,butwillimproveitssensitivityaftertheplannedmovetoadeepsiteintheSoudanmine.
6G.G.Raffelt
3NeutrinoAstronomy
IndirectmethodstosearchforWIMPsrelyontheirannihilationinthegalactichaloorinthecenteroftheSunorEarthwhereWIMPscanbetrapped[20].ThesearchforGeV–TeVneutrinosfromtheSunorEarthintheKamiokande,Baksan,andMACROdetectors[32]alreadytouchthepa-rameterrangerelevantforneutralinodarkmatter[33].Neutrinotelescopesarethuscompetitivewithdirectdark-mattersearches,whereitdependsondetailsofthesupersymmetricmodelswhichapproachhasabetterchanceoffindingneutralinos.Roughly,awateroriceCherenkovdetectorrequiresakm3volumetobecompetitivewiththeCDMS-Soudansearchgoal.
Afterthesaddemiseofthedeep-seaDUMANDprojectakm3neutrinotelescopehasagaincomewithinrealisticreachafterthebreathtakingprogressinthedevelopmentoftheAMANDAiceCherenkovdetectoratthesouthpole[34].ThelakeBaikalwaterCherenkovdetector[37]isanotheropera-tionalneutrinotelescope,butprobablyitcannotreachthekm3size.Theprospectsofthedeep-seaprojectsNESTOR[35]andANTARES[36]intheMediterraneandependontheoutcomeoftheircurrent“demonstrator”phase.Eitherway,aftertheexplosivedevelopmentofsolarandatmosphericneutrinoobservatories(MeV–GeVenergies),high-energyneutrinoastronomyissettobecomearealityintheverynearfuture.
Besidesthesearchfordarkmatter,neutrinoastronomyaddressesanotheroldandenigmaticastrophysicalproblem,theoriginofcosmicrayswhichengulftheEarthwithenergiesupto∼1020eV.Theyconsistofprotonsandnucleiwhichmustbeacceleratedsomewhereintheuniverse.Whenevertheyrunintostufftheyproducepionsandthusneutrinosandphotonsinroughlyequalproportions(“cosmicbeamdumps”).Becausetheuniverseisopaquetophotonswithenergiesexceedingafew10TeVduetopairproductiononthecosmicmicrowavebackground,andbecausechargedparticlesaredeflectedbymagneticfields,high-energyneutrinoastronomyoffersauniqueobservationalwindowtotheuniverse,andespeciallyachancetoidentifythesitesofcosmic-rayacceleration[38].
4TeVγ-RayAstronomy
Perhapsthemostattractivesitesforthecosmic-rayaccelerationareactivegalacticnuclei(AGN)whicharelikelypoweredbyaccretingblackholes.Theseobjectstendtoejecthugejetsinoppositedirections;foranestimateoftheexpectedneutrinofluxseeRef.[39].Ifthisisindeedthecaseonewouldequallyexpecthigh-energyγ-raysfromthesesources.Remarkably,forthepastfewyearsTeVγ-rayshaveindeedbeenobserved[40,41,42]fromthetwonearby(∼300millionlight-years)AGNsMarkarian421and501whichhavejetspointingtowardEarth.
PL8:Astro-ParticlePhysics7
Untilrecentlyγ-rayastronomyreachedonlyupto∼20GeVbecausethelowfluxesathigherenergiesrequireforbiddinglylargesatellites.Theobser-vationalbreak-throughintheTeVrangearosefromImagingAirCherenkovTelescopes(IACTs)ontheground[43].Ahigh-energyγ-rayhitstheupperatmosphereatanaltitudeof∼16kmandproducesanelectromagneticshowerwhichinturnproducesCherenkovlight.Witharelativelycrudetelescopeonecanthustakeanimageoftheshower.Theaxesofthecigar-shapedshowerimagesofmanyγ-raysintersectinonepointwhichcorrespondstotheloca-tionofthesourceintheskyandthusallowsonetodiscriminateagainstthemuchlargerbutisotropicfluxofhadroniccosmicrays.Anumberofgalacticsourcesarenowroutinelyobserved,notablytheCrabnebula,whichisseenatenergiesupto50TeVandservesasa“calibration”source.Thereremainsanunexploredspectralrangebetweenabout20and300GeVwhichrequiresmuchlargerIACTsthanarecurrentlyavailable.
TheMarkariansarethefirstextragalacticsourcesintheTeVγ-sky.Theirbehaviorisquitetantalizinginthattheyarehugelyvariableonsub-hourtimescales(Fig.4).Moreover,Mrk501essentially“switchedon”fromastateoflowactivitywithabout0.1oftheCrabfluxin1995,about0.3in1996,to
Background subtracted count rate [ mHz ]160140120100806040200MarchApril1 Craba)1617181920217891011121314Date in March/April 1997April 12April 13April 142001501005002b)345234523Time of observation [ UTC ]45Fig.4.DetectionrateoftheactivegalaxyMrk501intheHEGRAstereoscopicsystemofImagingAirCherenkovTelescopesonanightbynightbasis,a)forthewholedatasetandb)forthelast3nightsin5min.intervals[42].Thedashedlinesindicatetheaveragepernight,thedottedlineshowstheCrabdetectionrateasareference.Errorsarestatisticalonly.
8G.G.Raffelt
about10timestheCrabsinceFebruary1997.Ifthehigh-energyphotonsareproducedbyaprotonbeamor,say,photonupscatteringbyacceleratedelectronsisbynomeansobvious.Onewillneedneutrinotelescopestodecidethisquestionandthustounderstandtheseintruigingobjects.
5Summary
Experimentstoidentifythephysicalnatureofthegalacticdarkmatterhaverecentlymadegreatstrides.ThemicrolensingsearchesforMACHOshaveobservedaroundadozencandidatestowardtheLargeMagellanicCloud,butaninterpretationoftheseeventsisquitepuzzlinginthattheirbest-fitmassputsthemintothewhite-dwarfcategorywhichishighlyimplausible.ThisyearafirstcandidatetowardtheSmallMagellanicCloudhasbeenreported,withanevenlargerapparentmass.Fromvirtuallyanycosmologicalperspec-tivecolddarkmatterremainsthefavoredhypothesisforthedominantmassfractionoftheuniverse.Full-scalesearchesforthemostfavoredparticlecan-didates(axionsandWIMPs)areinprogress.OnecanhuntWIMPsalsobysearchingfortheirannihilationproductsintheformofhigh-energyneutrinosfromtheSunorthecenteroftheEarth.Withakm3wateroriceCherenkovdetectoronecouldcoverasignificantfractionoftheparameterspaceforsu-persymmetricdarkmatter.TheimpressiveprogressoftheAMANDAsouthpoledetectorandtheappearanceofnewdeep-seaprojects(ANTARESandNESTOR)bodewellforthisapproach—akm3detectorcouldbeupandrunningbeforetheLHC.High-energyneutrinoastronomyhasotherintruig-ingobjectives,notablysearchingforthesitesofcosmic-rayacceleration.ThebreathtakingrecentobservationsofTeVγ-raysfromthetwonearbyactivegalaxiesMarkarian421and501havezoomedthisphysicstargetintosharperfocus.Whetherornotactivegalacticnucleiaccelerateprotonsisaquestionthatcanbeansweredonlybyneutrinoastronomy.Acknowledgments
Thisworkwassupported,inpart,bytheDeutscheForschungsgemeinschaftundergrantNo.SFB375.
References
[1]M.Nakahata,PL11,theseProceedings.
[2]V.Trimble,Annu.Rev.Astron.Astrophys.25(1987)425.S.Tremaine,
PhysicsToday45:2(1992)28.
[3]E.W.KolbandM.S.Turner,TheEarlyUniverse(Addison-Wesley,Red-woodCity,1990).G.B¨orner,TheEarlyUniverse,2ndedition(Springer,Berlin,1992).
PL8:Astro-ParticlePhysics9
[4]B.J.Carr,CommentsAstrophys.14(1990)257;Annu.Rev.Astron.As-trophys.32(1994)531.B.J.CarrandM.Sakellariadou,Fermilab-Pub-97-299-A,Astrophys.J.(submitted1997).D.J.HegyiandK.A.Olive,Astrophys.J.303(1986)56.[5]B.Paczy´nski,Astrophys.J.304(1986)1.
[6]C.Alcocketal.(MACHOCollab.),Nature365(1993)621;Phys.Rev.
Lett.74(1995)2867.E.Aubourgetal.(EROSCollab.),Nature365(1993)623;Astron.Astrophys.301(1995)1.R.Ansarietal.(EROSCollab.),Astron.Astrophys.314(1996)94.
[7]C.Renaultetal.(EROSCollab.),Astron.Astrophys.324(1997)L69.[8]C.Alcocketal.(MACHOCollab.),Astrophys.J.471(1996)774;As-trophys.J.486(1997)697.
[9]K.Sahu,Nature370(1994)275.H.S.Zhao,astro-ph/9606166,9703097.
C.Alcocketal.(MACHOCollab.),Astrophys.J.490(1997)L59.A.Gould,astro-ph/9709263.N.Evansetal.,astro-ph/9711224.E.Gatesetal.,astro-ph/9711110.D.ZaritskyandD.Lin,astro-ph/9709055.[10]C.Alcocketal.(MACHOCollab.),Astrophys.J.491(1997)L11.
N.Palanque-Delabrouille(EROSCollab.),astro-ph/9710194.
[11]A.P.S.CrottsandA.B.Tomaney,Astrophys.J.473(1996)L87.R.An-sarietal.(AGAPECollab.),Astron.Astrophys.324(1997)843.
[12]J.Yokoyama,Astron.Astrophys.318(1997)673.K.Jedamzik,Phys.
Rev.D55(1997)R5871.J.C.NiemeyerandK.Jedamzik,astro-ph/9709072.
[13]R.D.PecceiandH.R.Quinn,Phys.Rev.Lett.38(1977)1440;Phys.
Rev.D16(1977)1791.S.Weinberg,Phys.Rev.Lett.40(1978)223.F.Wilczek,Phys.Rev.Lett.40(1978)279.J.E.Kim,Phys.Rept.150(1987)1.H.-Y.Cheng,Phys.Rept.158(1988)1.
[14]R.L.Davis,Phys.Lett.B180(1986)225.R.A.BattyeandE.P.S.Shel-lard,Phys.Rev.Lett.73(1994)2954;(E)ibid.76(1996)2203.D.HarariandP.Sikivie,Phys.Lett.B195(1987)361.C.HagmannandP.Sikivie,Nucl.Phys.B363(1991)247.
[15]P.Sikivie,Phys.Rev.Lett.51(1983)1415;Phys.Rev.D32(1985)2988.[16]C.Hagmann,P.Sikivie,N.S.Sullivan,D.B.Tanner,Phys.Rev.D42
(1990)1297.
[17]W.U.Wuenschetal.,Phys.Rev.D40(1989)3153.
[18]C.Hagmannetal.,Nucl.Phys.Proc.Suppl.51B(1996)209.
[19]I.Ogawa,S.MatsukiandK.Yamamoto,Phys.Rev.D53(1996)R1740.[20]G.Jungman,M.KamionkowskiandK.Griest,Phys.Rept.267(1996)
195.
[21]M.W.GoodmanandE.Witten,Phys.Rev.D31(1985)3059.
[22]J.Primack,D.SeckelandB.Sadoulet,Annu.Rev.Nucl.Part.Sci.38
(1988)751.P.F.SmithandJ.D.Lewin,Phys.Rept.187(1990)203.D.O.Caldwell,Mod.Phys.Lett.A5(1990)1543;Proc.TAUP97,tobepublished.N.E.Booth,B.CabreraandE.Fiorini,Annu.Rev.Nucl.Part.Sci.46(1996)471.A.Watson,Science275(1997)1736.
10G.G.Raffelt
[23]P.F.Smithetal.,Phys.Lett.B379(1996)299.J.J.Quenby,Astropart.
Phys.5(1996)249.
[24]R.Bernabeietal.,Phys.Lett.B389(1996)757.
[25]D.Reusseretal.,Phys.Lett.B255(1991)143.E.Garciaetal.,Phys.
Rev.D51(1995)1458.M.Becketal.,Phys.Lett.B336(1994)141.[26]P.Gondolo,privatecommunication(1997).[27]L.Bergstr¨omandP.Gondolo,Astropart.Phys.5(1996)263.A.Bottino,
F.Donato,G.MignolaandS.Scopel,Phys.Lett.B402(1997)113.J.Edsj¨oandP.Gondolo,Phys.Rev.D56(1997)1879.
[28]M.Sistietal.,in:Proc.7thInt.WorkshoponLowTemperatureDe-tectors(LTD-7),27July–2August1997,Munich,Germany,ed.byS.Cooper(Max-Planck-Institutf¨urPhysik,Munich,1997).
[29]S.W.Nametal.,in:Proc.7thInt.WorkshoponLowTemperatureDe-tectors(LTD-7),27July-2August1997,Munich,Germany,ed.byS.Cooper(Max-Planck-Institutf¨urPhysik,Munich,1997).
[30]R.Bernabeietal.,astro-ph/9710290,tobepublishedinProc.TAUP97.[31]A.Bottino,F.Donato,N.FornengoandS.Scopel,astro-ph/9709292
and9710295.
[32]M.Morietal.(KamiokandeCollab.),Phys.Rev.D48(1993)5505.
M.M.Bolievetal.(Baksantelescope),in:Proc.TAUP95,ed.byA.Morales,Nucl.Phys.B(Proc.Suppl.)48(1996)83.M.Ambrosioetal.(MACROCollab.),PreprintINFN-AE-97-23.
[33]M.Kamionkowskietal.,Phys.Rev.Lett.26(1995)5174.V.Berezinskii,
etal.,Astropart.Phys.5(1996)333.L.Bergstr¨om,J.Edsj¨oandP.Gondolo,Phys.Rev.D55(1997)1765.[34]L.Berstr¨om,astro-ph/9612122,Proc.IdentificationofDarkMatter,
Sheffield,UK,Sept.1997.F.Halzen,astro-ph/9707289.
[35]E.G.Anassontzisetal.(NESTORCollab.)PreprintDFF-283-7-1997,
Jul1997.Proc.18thInternationalSymposiumonLepton-PhotonInter-actions(LP97),Hamburg,Germany,28July–1Aug.1997.[36]ANTARESCollaboration,Proposal,astro-ph/9707136.
[37]V.A.Balkanov(BaikalCollab.),astro-ph/9705017,Proc.XXXIIRen-contresdeMoriond,LesArcs,France,Jan.18–25,1997.
[38]T.K.Gaisser,astro-ph/9707283,Proc.OECDMegascienceForumWork-shop,Taormina,Italy,May22–23,1997.F.Halzen,astro-ph/9605014,Proc.VenitianNeutrinoConference,Feb.1996.[39]F.HalzenandE.Zas,Astrophys.J.488(1997)669.
[40]M.Punchetal.,Nature358(1992)477.A.D.Kerricketal.,Astrophys.
J.438(1995)L59.D.Petryetal.,Astron.Astrophys.311(1996)L13.[41]J.Quinnetal.,Astrophys.J.456(1996)L83.
[42]F.Aharonianetal.(HEGRACollab.),Astron.Astrophys.327(1997)
L5.M.Cataneseetal.,astro-ph/9707179.
[43]J.V.JelleyandT.C.Weekes,Sky&Telescope,Sept.1995,pg.20.
因篇幅问题不能全部显示，请点此查看更多更全内容