icecube searches for neutrinos from dark matter annihilations in the
TRANSCRIPT
M.RameezSwissPhysicalSocietyMeeting2016
23rd August2016
IceCube searches for neutrinos from dark matter annihilations in the Sun and Cosmic Accelerators
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TheIceCube NeutrinoObservatory
Eν >100GeV
Eν >10GeV
~41oinice
Cherenkovradiation.
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In-iceSignatures
Goodangularresolution:NeutrinoAstronomy◦ (~0.6o at10TeV)◦ Vertexcanbeoutsidethedetector:Increased
effectivevolume!
Muontracks→ νμ CC
𝜈𝜇 𝜈e
cascades →allflavors
• νe,ν𝞃 andall-flavorneutralcurrent• Fullyactivecalorimeter:Highenergyresolution• Angularreconstructionabove~50TeV
Inbothcases,𝜈 and�̅� areindistinguishable
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DarkMatter• GalacticRotationCurves:
• GravitationalLensingduetogalaxyClusters:BulletCluster:astro-ph/0608247
• PrecisionCosmology• PlanckCMBMeasurements• CDMsimulationssuchasMillenium reproduceobservedLSS
Ω&' ≥ 0.1
Ω&'~0.2 − 0.4
Ω&' = 0.268 ± 0.02
WeknowDMexistsfrom:
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WeaklyInteractingMassiveParticlesDarkMatterasathermalrelicoftheEarlyuniverse.
• Boltzmannequationoftheearlyuniverse• &56
&7+ 3𝐻𝑛< = − σ>55𝑣 𝑛<@ −𝑛AB<@
• RelicΩCD~0.27For σ>55𝑣 = 3. 10F@G𝑐𝑚J/𝑠
σ>55𝑣 ≈ NOP /QR P
DP ≈ 3. 10F@G𝑐𝑚J/𝑠
• StableWIMPSpresentinvarioustheories• Neutralino inSUSYtheories• Kaluza Kleinparticles. Freezeout
𝑋
𝑋T
𝑓
𝑓̅𝑀𝑔X 𝑔X
WIMPMiracle
WIMP Capture and Annihilation in the Sun
6
AtEarth:EnhancedneutrinofluxfromthedirectionoftheSun!
𝜒ScatteringCross
SectionNumberdensityofelementi ->SolarModel𝜎[C ∝ 𝐽(𝐽 + 1)
𝜎[` ∝ 𝐴@
Capture
Annihilation
ΓcABde =
12 𝐶gEquilibrium
SpinDependentscattering• OnlythehydrogenintheSuncontributes
significantly.• Lowereventratesindirectdetection
experiments• MoreinterestingforIceCube
SpinIndependentscattering• Heaviernucleicontributemoredueto∝ 𝐴@ enhancement.
• BettersensitivityusingdirectdetectionexperimentssuchasLUX,XENONetc
AllcalculationsperformedwithDarkSusy/WimpSim
𝑏T,𝑊F,𝜏F…
𝑏,𝑊k,𝜏k…
Primaryannihilationchannels De
cay
DenseMediumInteractions
MatterOscillations
….ν
….νT
prop
agation
Vacuumoscillations
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EventsinIceCube
atmospheric µbackground
ν induced µ
Northern Skycosmic ray
νatm
atmospheric μOverwhelming background cosmic ray
Southern Sky
Austral Winter
Austral Summer
106 lowerbackgroundduringtheAustralWinter
Upgoingevents
Downgoingevents
ObserveddataMisreconstructed μ
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EventSelectionStrategy
• HighEffectivevolume(IceCube)
• Goodangularresolution(<2O at1TeV)
• BadEnergyresolution(Onlyalowerlimit)
• >100GeV
• SmallerEffectivevolume(DeepCore)
• Worseangularresolution(8O at50GeV)
• GoodEnergyresolution~20%below100GeV
• <100GeV
• SmallerEffectivevolume(DeepCore)
• Worseangularresolution• (14O at30GeV)• GoodEnergyresolution~20%below60GeV
• <100GeV
AttemptstoisolateadowngoingIceCube dominatedsamplewerenotsuccessfulduetoμ background.
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Samples
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Level4- Veto3
LowEnergy
μ
✘ ✓
μ
νμConeRT Veto
Muonssneakpastcutsonstartingvertex.(Falselyreconstructedstartingvertex)
Lookforhitswithina40degreecone.Sortthemintoclusters:within250metres and1μsofeachother
Countthesizeofthelargestcluster
Cutat3rejects>80%ofBkg,keeps90%ofSignal.
Level 5 – Boosted Decision Tree (contd)
2
BestBDTcutthresholdforsensitivitychosen- theModelRejectionFactormethod.
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FinalSamplesSummary
SampleRate(mHz)
TotalMC(mHz)
Atmos𝝂𝝁 + 𝝂o𝝁(mHz)
Atmos𝝂𝒆 + 𝝂o𝒆(mHz)
Atmosμ
(mHz)
Energyrange(GeV)
Typicalsignalefficiency
WinterHighEnergy 2.9 3.0 2.1 0.1 0.8 100-2000 24%(5 TeV χχ toW+W-)
Winter LowEnergy 0.34 0.36 0.26 0.08 0.02 10-100 6%(50 GeVχχ toτ+τ-)
Summer 0.25 0.28 0.21 0.05 0.03 10-50 4%(20 GeVχχ toτ+τ-)
1
3
2
• Livetimes :Winter528.28days,Summer490.77days.Total1019.05daysofdata.• Nonoverlapping,noeventsincommon• Trueeventdirectionsnotexamined.Analysisisblind.
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EventSelectionPerformance
EnergyReconstruction
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Afullneutrinoenergyestimatorforcontainedtracks
Enhancessignaltobackgrounddiscrimination,andsensitivityfortheDeepCore dominatedsamples
and2 3
EventenergyinformationusedforaSolarWIMPanalysisforthefirsttimeinIceCube.
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AnalysisMethodBackground(atmosphericν andμ):
• Uniformwithindeclinationband𝐵(𝛿e)
Signal(Astrophysicalν fromsource):• Clusteredaroundsource
Ktu = vwA
xwyz{ | }w~}�(�w)
@�(AxwFA~xw)FisherBinghamdistribution,(Gaussianindirectionalstatistics)
Eventbyeventangularresolution
Backgroundonly
Background+PSat120O,90O
Useeventdirection:
Andenergy:
St 𝑚�, 𝑐ℎ = 𝑃 𝐸e 𝑚�, 𝑐ℎ ∗ Ktu 𝐵e = 𝑃 𝐸e 𝜙>7' ∗ 𝐵 𝛿e
𝓛 𝑛� = �𝑛�𝑁 St 𝑚�, 𝑐ℎ + (1 −
𝑛�𝑁)𝐵e
�
e��
Likelihood:
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AnalysisMethod(contd)
• 𝐵(𝛿e) and 𝑃 𝐸e 𝜙>7' areestimatedfromdata.• Robustagainstfalsediscovery
• 𝑃 𝐸e 𝑚�, 𝑐ℎ isestimatedfromMonteCarlo
• Ktu isanalytic.
• Loglikelihoodcanbemaximizedtofindthebestfit𝑛��• −2 log 𝓛 5���
𝓛 5��istheteststatisticsandis
distributedas𝜒@(1dof) – (Wilke’stheorem)• SignificancefrommanydatasetsscrambledinR.A.• Confidenceintervalson𝑛� - FeldmanandCousins.
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1
2
3
Results• Nostatisticallysignificantexcess• Bestp– value~16%
500GeV𝜒𝜒 → 𝑏𝑏T𝑛�� = 24.4
PhD Thesis Defense - M. Rameez17PhD Thesis Defense - M. Rameez
1
2
3
Results
17
Improvements + More livetime + bugfix - > limits are lower by almost an order of magnitude w.r.t IC79
17M. Rameez – Universite de Geneve
Morelivetime +bettereventselection+betteranalysismethods+bugfix ->Resultsbetterby~1orderofmagnitudew.r.t IC79
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AstrophysicalUncertainties
DMvelocitydistributionfunctions
Thereareuncertaintieson:• ThevelocityoftheSunw.r.tthehalo
• ThefractionofDMinaco-rotatingdarkdisk• Thegalacticescapevelocity
C.Rott etal.JCAP05(2014)049
Theuncertaintiesare20%(50%)atlow(high)WIMPmasses.
Conservativew.r.t.thedarkdiskfraction.
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ComplementarityandDMModels
PhD Thesis Defense - M. Rameez18
Complementarity and DM models
Missing ET
<σannv>
σ�-N
18M. Rameez – Universite de Geneve
PhD Thesis Defense - M. Rameez18
Complementarity and DM models
Missing ET
<σannv>
σ�-N
18M. Rameez – Universite de Geneve
< 𝜎>55𝑣 >
𝜎�F�
Missing𝐸�
ComplementarityinthepMSSM
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Only pMSSM models not excluded by LHC Run 1 are shown Correct Higgs Mass and Relic density SI σχ-N not greater than LUX bounds Model colourcoded by hardness or softness of annihilation channels “PMSSM benchmark models for Snowmass 2013” arXiv:1305.2419,
148.3 GeV Bino-Higgsino WIMP can be excluded at >90% C.L
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PhD Thesis Defense - M. Rameez22
22M. Rameez – Universite de GeneveM. Rameez – Universite de GeneveM. Rameez – Universite de Geneve
arXiv:1505.06513
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PhD Thesis Defense - M. Rameez23
Complementarity of DM Searches in a Consistent Simplified Model: the Case of Z'T. Jacques et. al. arXiv:1605.06513
U(1)' extension of the standard model :
SU(3)C X SU(2)L X U(1)Y X U(1)'
One new gauge boson Z' (mass mz' given by SSB in a hidden sector)
Majorana DM, stable under Z2 symmetry
U(1)' charges for cancellation of SM X SM X U(1)' gauge anomaly. Higgs is charged
Full lagrangian in backup slides
SD WIMP-Nucleon scattering in the non relativistic limit – Direct Detection constraints
Z-Z' mixing
LHC constraints from Z' → l+l- and monojet constraints on DM
Strongest constraints are from LHC below 400 GeV WIMP mass, and IC above 400 GeV, except for θ = π/2
23M. Rameez – Universite de Geneve
U(1)' extension of the standard model :
SU(3)C×SU(2)L ×U(1)Y×U(1)'
One new gauge boson Z'
(mass mz' given by SSB in a hidden sector) Majorana DM, stable under Z2 symmetry U(1)' charges for cancellation of SM X SM X U(1)' gauge anomaly. Higgs is charged Full lagrangian in backup slides SD WIMP-Nucleon scattering in the non relativistic limit –Direct Detection constraints Z-Z' mixing LHC constraints from Z' → l+l- and monojet constraints on DM Strongest constraints are from LHC below 400 GeV WIMP mass, and IC above 400 GeV, except for θ = π/2
Complementarity of DM Searches in a Consistent Simplified Model: the Case of Z' T. Jacques et. al. arXiv:1605.06513
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TheEmerging750GeVdiphoton excess– portaltothedarksector?E.Morgante et.al.,JHEP1607(2016)141
Apseudoscalar,Pofmass750GeV:• ScatteringisSDattheNRlimit
750GeV>Ewk Scale• Lagrangian isSU(2)L invariant,PcouplestoB.• GuaranteesannihilationtoZZandZγ
Palsocouplestogluonsand/orquarks• Run1constraints
DMχ (fermion)orφ (scalar)stableunderZ2 symmetry.3scenarios.Pcouplesto :
• B,g,u,χ• B,g,u,χ,b• B,g,u,χ,t
WIMP-protonscatteringintheNRlimit𝑖(𝑆¡�.
B�'¢) forscalarDMand
(𝑆¡�.B�'¢) (𝑆¡�.
B�'¢) forfermionicDM
(IClimitscalculatedusingcaptureratesevaluatedinR.Catenaetal,JCAP1504(2015)04,042)andanalyticalsimplificationofICsensitivity.
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TheEmerging750GeVdiphoton excess– portaltothedarksector?E.Morgante et.al.,JHEP1607(2016)141
Apseudoscalar,Pofmass750GeV:• ScatteringisSDattheNRlimit
750GeV>Ewk Scale• Lagrangian isSU(2)L invariant,PcouplestoB.• GuaranteesannihilationtoZZandZγ
Palsocouplestogluonsand/orquarks• Run1constraints
DMχ (fermion)orφ (scalar)stableunderZ2 symmetry.3scenarios.Pcouplesto :
• B,g,u,χ• B,g,u,χ,b• B,g,u,χ,t
WIMP-protonscatteringintheNRlimit𝑖(𝑆¡�.
B�'¢) forscalarDMand
(𝑆¡�.B�'¢) (𝑆¡�.
B�'¢) forfermionicDM
(IClimitscalculatedusingcaptureratesevaluatedinR.Catenaetal,JCAP1504(2015)04,042)andanalyticalsimplificationofICsensitivity.
No750GeVdiphoton Excess!
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SearchesforneutrinosfromCosmicAccelerators
Galactic Extragalactic?
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CosmicAcceleratorsandIceCubeCRs,wheredotheycomefrom?Whatacceleratesthem?• Galactic:SNRs,microquasars?• Extragalactic:AGNs,galaxyclusters,starburstgalaxies,
GRBs?Howaretheyaccelerated?Firstorderfermiacceleration–predictsparentprotonspectrumofpowerlaw𝐸F@ foranidealshock.• Neutrinosproducedatsourcewithsamepowerlaw
spectrumthroughp-pandp-γ interactions– piondecay–muondecay.
• 1:2:0atsource→1:1:1atEarth.
54eventsseenonanexpectedbackgroundof12.6± 5.1𝜇 and9.0F@.@k¤.�𝜈. Atmosphericonlyoriginrejectedat >6𝜎 Nostatisticallysignificant
clustering
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~400000tracks,fromIC40,59,79and86(4yearsofIceCube)Northernsky:μ from𝜈³ + �̅�³ CCinteractionsSouthernsky:Atmosphericμ
Allskypointsourcesearches:nostatisticallysignificantexcess–correctingfortrials
TheIceCube samplesofeventsdedicatedtoPSsearches
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TheStackingMethod
STACKING
Source1 Source2 Source3
r.a.
𝑆e7´7 =∑ ¶�·¸¹ º�,» [w
�¢��¼½
∑ ¶�·¸¹ º�,»¢��¼½
Theoreticalweight𝑊u,detectoracceptance𝑅`¿ 𝛿u, 𝛾
Sourcesthatareindividuallytooweakcanstillbedetectedasacatalog
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StackingSearchExample:MilagroHotspots•6 TeV associations with supernova remnants based on Milagro observations. Models
from Halzen et al. Pvalue=1.99%inIC86+79+59
F.Halzen,A.Kappes andA.O’Murchadha (Phys.Rev.D78:063004,2008)
Compatiblewiththebackgroundonlyhypothesis.
Similarexcess(2%)observedinIC40aposteriori,henceexcluded.
Moredatarequired.
Update:Withmoredata,thesignificancehasreducedagain.25%pvalue(SeeTalkbyTessaCarver:TASKIIIsession1745hrs)
Probablyabackgroundfluctuation
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Summary/Conclusions
Asearchwascarriedoutforν fromWIMPannihilationsintheSun:• 3yearsofIceCube data,Innovativebackgroundrejection,improvedreconstructions• Unbinned maximumlikelihoodmethodusingenergyestimators
Weobtained:• Nostatisticallysignificantexcess• Themoststringentboundson𝜇 fluxfromthedirectionoftheSunabove80GeV• ThemoststringentconstraintontheSpinDependentWIMP-Nucleonscatteringcrosssection.• Canconstraintheoriesofsymmetricdarkmatterwithcandidatein10GeV-10TeVrange
SimilarmethodwasusedtosearchforneutrinosfromcandidatesitesforCRacceleration,suchasSNRs
Nostatisticallysignificantexcesswasfoundinanysearches
BackupSlides
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Results(contd)
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ConstraintscanbederivedalsoonahostofotherSDandSIvelocityandmomentumsuppressedoperators.
(R.Catenaetal,JCAP1504(2015)04,042)
DirectdetectionbetterforSIscattering
𝜎�F�dgÁAd�𝛼𝐴@
Systematic Uncertainties
33
Mass(GeV) Channel uncertaintyin%(+/-)
AbsoluteDOMefficiency
20 τ+τ− -11/+29
50 τ+τ− -8/+23
100 W+W− -9/+19
500 bbT -7/+11
1000 W+W− -6/+9
Photonpropagationinice:AbsorptionandScattering
20 τ+τ− -13/+18
50 τ+τ− -9/+13
100 W+W− -9/+11
500 bbT -8/+7
1000 W+W− -6/+4
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Photons>1cm ~1mm ~10μm ~1nm <0.1nm
10-6 eV 10-4 eV 10-1 eV ~1KeV > 100KeVPulsars,quasars,radiogalaxies TheBigBang(CMB) Nonthermalprocesses
MultimessengerAstronomy
CosmicRaysElectrons,protons,heavynuclei:108 - 1020 eV– Originsunknown.
GravitationalWavesPredictedbyGeneralrelativity– Observedfirstin2015BH-BHmerger~410MPc away.Phys.Rev.Lett.116(6):061102
Neutrinos
New
ProposedbyPauliin1930,detectedbyReines andCowans in1959,neutral,weaklyinteracting.TheSun,SN1987A– 10MeVDiffuseastrophysicalflux>50TeV ThisTalk
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Region not observableIn photons orCharged particles
Themessengerhorizonγ-raysdonottraveltoofar• 1TeV :ClosestAGNsCRscannotpointback• Deflection:fewdegreesat~50EeV• Horizon~100MPc – interactionswithCMBTheneutrino- idealmessengerforthenonthermaluniverse• Neutral,undeflected
– canpointback• Interactsonlyweakly
– cantravelGpc distances– hardtodetect
• Wehopetosee• ThesitesofCRacceleration• DarkMatterannihilation
IceCube wasbuilttolookforastrophysicalneutrinos.
Copenhagen-2015
DM within our own Galaxy
36
DMHalo
BaryonicMatterDisk
LocalDMdensity
M.Pato – ICRC2015
GlobalMethod:Average𝜌CD atradiusoforbitofSun~0.4 ± 0.1𝐺𝑒𝑉/𝑐𝑚J
LocalMethod:𝜌CD atthepositionoftheSun‘Local’and‘Global’methodsnowstartingtoagreeonthelocalDMdensitySeeH.Silverwood etal,ICRC2015.
GlobalMethod
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ν fromWIMPannihilationsintheSun
1TeV WIMP
FluxpredictionsfromWimpSim
Select:𝑊k𝑊F,𝜏k𝜏F (hardchannels)𝑏𝑏T (softchannel)
gg(evensofter)anddirectneutrino(evenharder)arenottheoreticallyfavoured
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Level3Cutexamples1
Reducedloglikelihood.Cutonquality,rejectsbadlyreconstructedevents.
Explicitcutonreconstructeddirectiontoselectonlyhorizontaltracks.
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Level3CutExamples(continued)
Zcoordinateofreconstructedstartingvertex.Selecteventsstartinglowerinthedetector.
2 3
DistancealongXYplanetostartingvertex.Selecteventsstartingnearcenterofthedetector.
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Level5– BoostedDecisionTreeMultivariateclassificationalgorithm:
Giveseacheventascore between-1.0(background)and+1.0(signal)Trainedonasampleofsignallikeandbackgroundlikeeventsusingselectedvariables.
Variableshavetooffer:GoodSignaltobackgroundseparationGoodData/MCagreement(avoidsimulationartifacts)
ZenithofvectorbetweenCOGandVertex
2
ExampleBDTvariable
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Level5– BoostedDecisionTree(contd)Prefervariablesthatarenotverycorrelatedwitheachother.
2
Signal Background
Ordifferentcorrelationsforsignalandbackground.
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ComplementarityandEFTs
J.BlumenthaletalPhys.Rev.D91,035002(2015)– IceCube lineupdatedto3yearsbyme
Majorana FermionWIMP,UniversalCouplingstoquarks,AxialVectorInteractions
EFT
Equilibriumrevisited
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Jungman andKamionkowsky (1996)
There’sathresholdσ[C belowwhichtheequilibriumconditionisnotavalidassumption
OurlimitswillremainabovethisthresholdforalongtimetocomeAssuming σc𝑣 ~ naturalscale.
UpcomingexperimentslikeCTAhavesensitivitytowardsDM σc𝑣 belowthenaturalscaleevenathighWIMPmasses
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OtherStackingSearches(Nosignificantexcess)SNRsyoungerthan10000years(Sedov TaylorPhase)
Starburstgalaxiesinthenearbyuniverse:Contribute<1%ofthediffuseastrophysicalflux
Supermassiveblackholes withintheGZKhorizon,fromthe2MASScatalog:Contribute<2%ofthediffuseflux
NearbyGalaxyClusters:Theoreticalpredictionsarebelowcurrentsensitivity.
ArrivaldirectionsofAugerandTAUHECRsabove85EeV
LimitsbetterthanAntaresanalysisbyafactorof25
UHECRsabove85EeV
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Periodicsearch– GammaRaybinaries
1)X-Ray binaries. characteristic radio emission believed to come from relativistic jets.Star
to observer
2) The neutrino flux expected at earth depends upon the orientation of our line of sight to these precessing jets.
3)Neutrino emission from these sources will follow the source PERIODICITY.
Trialfactorreduction:10microquasarsselected• Northernsky:detectedinGeV orhigher• Southernsky:detectedinTeV
TheHypothesis:AneutrinosignalwillhavethesameperiodicityastheopticalandX-rayobservations.(notnecessarilyinphasewithgamma)
Method:Lookforadirectionalexcessofeventsalsoclusteredinphase.
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PeriodicSearch(Results)
Pretrialpvalue:8.67%,Nosignificantexcess
Source HESS J0632+057
Posttrialpvalue44.3%
Backgroundonlyhypothesis.