1 towards a common skymap based on antares & icecube data j. brunner 24/09/2011
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Towards a common skymap based Towards a common skymap based on Antares & IceCube dataon Antares & IceCube data
J. BrunnerJ. Brunner
24/09/201124/09/2011
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ReminderReminder
Proposed at MANTS 2010Proposed at MANTS 2010 Agreed test sets:Agreed test sets:
• IC22IC22• IC22 UHEIC22 UHE• Antares 2007/2008Antares 2007/2008
Unblinded data provided recently Unblinded data provided recently (August 2011, Chad & Aart)(August 2011, Chad & Aart)• individual analyses publishedindividual analyses published
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Data taking periods & analysis Data taking periods & analysis samplessamples
ANTARES: analysis on 2007/2008 dataANTARES: analysis on 2007/2008 data IceCube: IC22, IC22-UHEIceCube: IC22, IC22-UHE Good overlap Good overlap
2007 2008 2009
IC40 IC59IC22
276 days5114 ev N 785 ev S
375 days14121 ev N22778 ev S
ANT-5 ANT-10-12 ANT-07-10
144 days740 ev S60%
151 days1350 ev S60%
A. Heijboer, C. Bogazzi
Ch. Finley
R. Lauer
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ProblemProblem Impressive analysis speed for both ANTARES & Impressive analysis speed for both ANTARES &
IceCubeIceCube• Antares : 2007-2010 analysis released Antares : 2007-2010 analysis released • IceCube : IC40, IC59 readyIceCube : IC40, IC59 ready
Old data sets are not anymore competitive, even Old data sets are not anymore competitive, even when combinedwhen combined
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Ch. Finley
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What can we learn anyway ?What can we learn anyway ?
Compare analysis methodsCompare analysis methods• Likelihood definitionsLikelihood definitions• Limit setting methodsLimit setting methods
Reproduce individual resultsReproduce individual results Propose common interfaces for Propose common interfaces for
possible future combined analysispossible future combined analysis
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Normalization and differencesNormalization and differences
IntInt44(F)=1(F)=1 IntInt44(B(Bii)=N)=Ntottot
NNtottot =Total number of =Total number of observed events in full observed events in full skysky
Signal events are Signal events are added on top of Nadded on top of Ntottot
IntInt5º5º(S(Sii)=1)=1 IntInt5º5º(B(Bii)=1 (B)=1 (Bii = cons) = cons) N = total number of N = total number of
observed events observed events inside search windowinside search window
Signal events are a Signal events are a fraction of Nfraction of N
Important to distinguish Integral over full sky versus Integral overVicinity of source to build likelihood (here 5 degrees)
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Combining SamplesCombining Samples(Antares method)(Antares method)
Add sum of j samplesAdd sum of j samples Each event knows from which sample it comes Each event knows from which sample it comes
(indices ij)(indices ij) Each sample has its own background PDF BEach sample has its own background PDF Bjj Each sample has its own PSF Each sample has its own PSF ßßjj But only one But only one sigsig can be fitted can be fitted Relative contributions of samples to signal Relative contributions of samples to signal
controlled by rcontrolled by rj j for each for each
sigj i
ijssijjsigbs r BFL j ,loglog
j
jr 1
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Signal eventsSignal events Unified in bins of 10 degreesUnified in bins of 10 degrees Event per declination per reference fluxEvent per declination per reference flux Used for signal simulation and rUsed for signal simulation and rj j
calculationcalculation
ANT07ANT08IC22-UHEIC22ALL
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Signal eventsSignal events Fraction of events per declination bandFraction of events per declination band Northern hemisphere: IC22 contributes more than Northern hemisphere: IC22 contributes more than
95%95% DEC<-50º: only ANTARESDEC<-50º: only ANTARES -50º -0º: ok-50º -0º: ok
ANT07ANT08IC22-UHEIC22
Declination range where both experiments contribute more than 10%Chance to get events from both samples close to source
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Code developmentCode development
Signal histosBackground
histosPSF
histos
Test experimentsFit within 5º from source
FilenamesNEXPNsig
Ra,Dec
Command line
Small root files
Root TreeTS,LH(S+B),LH(B),sig
Sensitivity Discovery power Flux limits
Root executableNo graphicsRuns in batch mode
Small Root MacrosGraphics output
Interactive
107 TE for BG-only 106 otherwise
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Example sky mapsExample sky maps Point source with 20 events includedPoint source with 20 events included
Rectascension
Declin
ati
on
ion
IC22IC22-UHEANT-2007ANT2008
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Example sky mapsExample sky maps Point source with 20 events includedPoint source with 20 events included
Rectascension
Declin
ati
on
ion
IC22IC22-UHEANT-2007ANT2008
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Example sky mapsExample sky maps Point source with 20 events includedPoint source with 20 events included Reasonable mixture of both setsReasonable mixture of both sets
Rectascension
Declin
ati
on
ion
IC22IC22-UHEANT-2007ANT2008
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Examples for TestStatisticsExamples for TestStatistics
• DEC=-35º More pronounced change in TS of More pronounced change in TS of
AntaresAntares
0 2 4 6 8 signal events 0 2 4 6 8 signal events
ANTARES IceCube
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Sensitivity versus actual limitsSensitivity versus actual limitsANTARES IceCube
Sensitivity is average of actual limit points50% of points above, 50% below
Sensitivity coincides with best limitsi.e. those which are most BG-like
Difference in treatment of TS=0 peak for bg-only test experiments IceCube: minimal p-value 0.5 if TS=0Antares: exploit tiny fluctuations around zero
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Fluctuations around TS=0Fluctuations around TS=0
BG-only TS
A. Heijboer
log(TS+0.001)
TS=0
My analysis:Same procedure but spread introduced “by hand” (random number)
BG-only TS
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Compare methodsCompare methods
Compare limit setting methodsCompare limit setting methods• NeymanNeyman• CLsCLs
Compare TS=0 treatment differenceCompare TS=0 treatment difference• Choose random value in Q1 when TS=0Choose random value in Q1 when TS=0
-3<Q1<-2-3<Q1<-2
• Choose Fixed value at 50%/50%Choose Fixed value at 50%/50% Q1=-2.5Q1=-2.5
Look at 90% C.L. event number limits Look at 90% C.L. event number limits
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Comparison of limit setting methodsComparison of limit setting methods
DEC=+35ºNeymanMedian=3.8
DEC=-35ºNeymanMedian=2.7
DEC=+35ºCLs methodMedian=5.8
DEC=-35ºCLs methodMedian=3.8
DEC=-70ºAntares
Neyman2.0
F&C2.4
CLs2.8
A. Heijboer
When TS=0Choose a random number -3<Q1<-2
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Comparison of limit setting methodsComparison of limit setting methods
DEC=+35ºNeymanMedian=3.1
DEC=-35ºNeymanMedian=2.2
DEC=+35ºCLs methodMedian=5.8
DEC=-35ºCLs methodMedian=3.8
DEC=-70ºAntares
Neyman2.0
F&C2.4
CLs2.8
A. Heijboer
When TS=0useQ1<-2.5
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ANTARES 2007-2008ANTARES 2007-2008
Present analysis
Good agreement for overfluctuatingSky points, difference for TS=0
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Results : Combined analysisResults : Combined analysis Real skymapReal skymap
IC22IC22-UHEANT07/08
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Discovery potential & SensitivityDiscovery potential & Sensitivity Reproduce Antares & IC22 where one experiment Reproduce Antares & IC22 where one experiment
dominatesdominates Coherent limit for whole skyCoherent limit for whole sky Factor 2 gain for specific declinationsFactor 2 gain for specific declinations
90% C.L. sensitivity
CombinedIC22Antares
5 sigma discovery
CLs method used here
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Selected source listSelected source list
Start with source lists as specified in Start with source lists as specified in Antares & IceCube papersAntares & IceCube papers
Recalculate individual flux limitsRecalculate individual flux limits Compare to combined flux limitsCompare to combined flux limits
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Results : selected source listsResults : selected source lists Important improvement for limits on Important improvement for limits on
Southern hemisphere when combining Southern hemisphere when combining samplessamples
Marginal effect on Northern hemisphereMarginal effect on Northern hemisphere
ANTARESANT & IC22-UHE
IC22ANT & IC22(UHE)
ANTARES source list IC22 & IC22-UHE source list
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Fullsky searchFullsky search
ClusteringClustering• Individual set Individual set
at least 4 events within 3 degreesat least 4 events within 3 degrees
• Combining setsCombining sets At least one 1 per set within 3 degreesAt least one 1 per set within 3 degrees
FitFit• 3 parameters within 5-10 degrees3 parameters within 5-10 degrees
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Fullsky search - SouthFullsky search - South
ANTARESANTARESEvent within 3 degrees: 5 Ra 43.18 Dec -0.56Signal events 3.4 Lambda 8.1
Confirmed from Antares PaperRa 43.21 Dec -0.50Signal events 3.4 Lambda 6.8
CombinedCombinedEvent within 3 degrees: 4 Ant + 4 IC22-UHE Ra 187.72 Dec -3.63Signal events 4.6 Lambda 8.0
Find new cluster !Compatible with background
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Fullsky search - NorthFullsky search - North
IC22IC22Event within 3 degrees: 14 Ra 191.27 Dec 18.79Signal events 9.5 Lambda 6.4
Different from IC22 PaperRa 153.4 Dec 11.4Signal events 7.7 gamma -1.65
CombinedCombinedEvent within 3 degrees: 1 Ant + 14 IC22 Ra 191.27 Dec 18.79Signal events 9.5 Lambda 6.2
Find same cluster !Compatible with background
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ANTARES versus IC40 ANTARES versus IC40 differential sensitivitiesdifferential sensitivities
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Dashed: IceCube , Full: ANTARES
Half decade bins5 sigma discovery potential
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ANTARES versus IC40 ANTARES versus IC40 Southern hemisphere onlySouthern hemisphere only
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Dashed: IceCube , Full: ANTARES
Half decade bins5 sigma discovery potential
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SummarySummary
Northern hemisphereNorthern hemisphere• Only marginal impact of ANTARESOnly marginal impact of ANTARES
Southern hemisphereSouthern hemisphere• Interesting efficiency gainInteresting efficiency gain• Improved limitsImproved limits• Enhanced potential for fluxes softer than Enhanced potential for fluxes softer than
E^-2E^-2
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Next stepsNext steps
Wait for stable results from individual Wait for stable results from individual experimentsexperiments• ANTARES 2007-201ANTARES 2007-201• IceCube IC40,59,79,86 (?)IceCube IC40,59,79,86 (?)
Use public event by event data Use public event by event data • Already available for IC40 diffuse setAlready available for IC40 diffuse set
Look at transient phenomenaLook at transient phenomena
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Public DataPublic Data