11

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

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

22

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

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

44

Ch. Finley

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

55

77

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)

88

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

1010

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

1111

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

1212

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

1414

Example sky mapsExample sky maps Point source with 20 events includedPoint source with 20 events included

Rectascension

Declin

ati

on

ion

IC22IC22-UHEANT-2007ANT2008

1515

Example sky mapsExample sky maps Point source with 20 events includedPoint source with 20 events included

Rectascension

Declin

ati

on

ion

IC22IC22-UHEANT-2007ANT2008

1616

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

1919

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

2525

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

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

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

2727

2828

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

2929

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

ANTARES 2007-2008ANTARES 2007-2008

Present analysis

Good agreement for overfluctuatingSky points, difference for TS=0

Results : Combined analysisResults : Combined analysis Real skymapReal skymap

IC22IC22-UHEANT07/08

3333

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

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

3434

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

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

3636

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

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

ANTARES versus IC40 ANTARES versus IC40 differential sensitivitiesdifferential sensitivities

4141

Dashed: IceCube , Full: ANTARES

Half decade bins5 sigma discovery potential

ANTARES versus IC40 ANTARES versus IC40 Southern hemisphere onlySouthern hemisphere only

4242

Dashed: IceCube , Full: ANTARES

Half decade bins5 sigma discovery potential

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

4343

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

4444

Public DataPublic Data