1 Towards a common skymap based on Antares & IceCube data J. Brunner 24/09/2011

Reminder Proposed at MANTS 2010 Proposed at MANTS 2010 Agreed test sets: Agreed test sets: IC22IC22 IC22 UHEIC22 UHE Antares 2007/2008Antares 2007/2008 Unblinded data provided recently (August 2011, Chad & Aart) Unblinded data provided recently (August 2011, Chad & Aart) individual analyses publishedindividual analyses published 2

Data taking periods & analysis samples ANTARES: analysis on 2007/2008 data ANTARES: analysis on 2007/2008 data IceCube: IC22, IC22-UHE IceCube: IC22, IC22-UHE Good overlap Good overlap IC40IC59IC days 5114 ev N 785 ev S 375 days ev N ev S ANT-5ANT-10-12ANT days 740 ev S 60% 151 days 1350 ev S 60% A. Heijboer, C. Bogazzi Ch. Finley R. Lauer

Problem Impressive analysis speed for both ANTARES & IceCube Impressive analysis speed for both ANTARES & IceCube Antares : analysis releasedAntares : analysis released IceCube : IC40, IC59 readyIceCube : IC40, IC59 ready Old data sets are not anymore competitive, even when combined Old data sets are not anymore competitive, even when combined 4 Ch. Finley

What can we learn anyway ? Compare analysis methods Compare analysis methods Likelihood definitionsLikelihood definitions Limit setting methodsLimit setting methods Reproduce individual results Reproduce individual results Propose common interfaces for possible future combined analysis Propose common interfaces for possible future combined analysis 5

6 Likelihood definitions so far : no energy, global PSF ANTARES: S+B likelihood ANTARES: S+B likelihood IceCube: S+B likelihood IceCube: S+B likelihood signal PDF Signal events Poisson mean PSF Position in sky Background rate Total event n s =  sig F = S i

7 Normalization and differences Int 4 (F)=1 Int 4 (F)=1 Int 4 (B i )=N tot Int 4 (B i )=N tot N tot =Total number of observed events in full sky N tot =Total number of observed events in full sky Signal events are added on top of N tot Signal events are added on top of N tot Int 5º (S i )=1 Int 5º (S i )=1 Int 5º (B i )=1 (B i = cons) Int 5º (B i )=1 (B i = cons) N = total number of observed events inside search window N = total number of observed events inside search window Signal events are a fraction of N Signal events are a fraction of N Important to distinguish Integral over full sky versus Integral over Vicinity of source to build likelihood (here 5 degrees)

8 Combining Samples (Antares method) Add sum of j samples Add sum of j samples Each event knows from which sample it comes (indices ij) Each event knows from which sample it comes (indices ij) Each sample has its own background PDF B j Each sample has its own background PDF B j Each sample has its own PSF ß j Each sample has its own PSF ß j But only one  sig can be fitted But only one  sig can be fitted Relative contributions of samples to signal controlled by r j for each  Relative contributions of samples to signal controlled by r j for each 

9 Combining Samples (IceCube method) N : total number of events form all samples within search cone N : total number of events form all samples within search cone One PSF per sample One PSF per sample B j might still be constant for small search cones B j might still be constant for small search cones Relative contributions of samples to signal controlled by r j for each  Relative contributions of samples to signal controlled by r j for each 

10 Signal events Unified in bins of 10 degrees Unified in bins of 10 degrees Event per declination per reference flux Event per declination per reference flux Used for signal simulation and r j calculation Used for signal simulation and r j calculation ANT07 ANT08 IC22-UHE IC22 ALL

11 Signal events Fraction of events per declination band Fraction of events per declination band Northern hemisphere: IC22 contributes more than 95% Northern hemisphere: IC22 contributes more than 95% DEC<-50º: only ANTARES DEC<-50º: only ANTARES -50º -0º: ok -50º -0º: ok ANT07 ANT08 IC22-UHE IC22 Declination range where both experiments contribute more than 10% Chance to get events from both samples close to source

12 Code development Signal histos Background histos PSF histos Test experiments Fit within 5º from source Filenames NEXP Nsig Ra,Dec Command line Small root files Root Tree TS,LH(S+B),LH(B),sig SensitivityDiscovery powerFlux limits Root executable No graphics Runs in batch mode Small Root Macros Graphics output Interactive 10 7 TE for BG-only 10 6 otherwise

13 Code development Everything is based on Root Everything is based on Root No dependence on heavy software packages like IceTray, SeaTray No dependence on heavy software packages like IceTray, SeaTray No dependence on custom formats like i3 No dependence on custom formats like i3 Test experiment drawing and LH fit coupled Test experiment drawing and LH fit coupled Restrict to 5º area around source for speed reasons Restrict to 5º area around source for speed reasons Heaviest part standalone executable Heaviest part standalone executable Mass production on batch farm at CC-LyonMass production on batch farm at CC-Lyon 18 declinations (-85º to 85º) in steps of 10º18 declinations (-85º to 85º) in steps of 10º Fixed (random) rectascensionFixed (random) rectascension Signal events from 0-29 : Total 540 jobs per roundSignal events from 0-29 : Total 540 jobs per round 10 7 TE for BG-only case, 10 6 otherwise10 7 TE for BG-only case, 10 6 otherwise

14 Example sky maps Point source with 20 events included Point source with 20 events included Rectascension Declinationion IC22 IC22-UHE ANT-2007 ANT2008

15 Example sky maps Point source with 20 events included Point source with 20 events included Rectascension Declinationion IC22 IC22-UHE ANT-2007 ANT2008

16 Example sky maps Point source with 20 events included Point source with 20 events included Reasonable mixture of both sets Reasonable mixture of both sets Rectascension Declinationion IC22 IC22-UHE ANT-2007 ANT2008

17 Example of Teststatistics 10 signal events added 10 signal events added Comparison of IceCube Antares LH ratio Comparison of IceCube Antares LH ratio Slight differences Slight differences Both too low in this example Both too low in this example

18 Examples for TestStatistics Antares method Antares method More pronounced change in TS in Southern hemisphere More pronounced change in TS in Southern hemisphere Less Background Less Background signal events DEC=-35º DEC=+35º

19 Examples for TestStatistics DEC=-35º More pronounced change in TS of Antares More pronounced change in TS of Antares signal events ANTARESIceCube

20 Examples for Fitted Nsig ANTARES method Antares region (South) Antares region (South) fitted values are systematic 8% lowfitted values are systematic 8% low Effect of 5º cutoff in PSF for fitEffect of 5º cutoff in PSF for fit IceCube IceCube Fitted values ok within 2%Fitted values ok within 2% Effect ignored in the following Effect ignored in the following signal events DEC=-35º DEC=+35º fitted fitted

21 Examples for Fitted Nsig On average compatible fit results On average compatible fit results Strange pattern in IceCube fit Strange pattern in IceCube fit Disappears for higher statistics (Northern hemisphere) Disappears for higher statistics (Northern hemisphere) signal events ANTARES fitted fitted IceCube

22 Discovery power Cumulative TS distribution for BG-only experiments Cumulative TS distribution for BG-only experiments Exponential fit Exponential fit Retain 3, 5 TS values from single-sided Gaussian ( , ) Retain 3, 5 TS values from single-sided Gaussian ( , ) DEC=-35º DEC=+35º

23 Discovery power Typical quote of discovery power: 50% chance to have a 3, 5 effect Typical quote of discovery power: 50% chance to have a 3, 5 effect DEC=-35º Single source DEC=-35º 24 sources approximation DEC=+35º 24 sources approximation

24 Results : Discovery power Declination dependence over full sky Declination dependence over full sky Trial factor for 24 sources included in approximate way Trial factor for 24 sources included in approximate way 3 53 5 3 53 5 Event numbers Neutrino Flux

25 Sensitivity versus actual limits ANTARESIceCube Sensitivity is average of actual limit points 50% of points above, 50% below Sensitivity coincides with best limits i.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=0 Antares: exploit tiny fluctuations around zero

Fluctuations 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 methods Compare limit setting methods Compare limit setting methods NeymanNeyman CLsCLs Compare TS=0 treatment difference Compare 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=-2.5 Q1=-2.5 Look at 90% C.L. event number limits Look at 90% C.L. event number limits 27

28 Comparison of limit setting methods DEC=+35º Neyman Median=3.8 DEC=-35º Neyman Median=2.7 DEC=+35º CLs method Median=5.8 DEC=-35º CLs method Median=3.8 DEC=-70º Antares Neyman 2.0 F&C 2.4 CLs 2.8 A. Heijboer When TS=0 Choose a random number -3<Q1<-2

29 Comparison of limit setting methods DEC=+35º Neyman Median=3.1 DEC=-35º Neyman Median=2.2 DEC=+35º CLs method Median=5.8 DEC=-35º CLs method Median=3.8 DEC=-70º Antares Neyman 2.0 F&C 2.4 CLs 2.8 A. Heijboer When TS=0 use Q1<-2.5

ANTARES Present analysis Good agreement for overfluctuating Sky points, difference for TS=0

IC22 Find compatible results with publication Find compatible results with publication 90% C.L. flux limits

Results : Combined analysis Real skymap Real skymap IC22 IC22-UHE ANT07/08

33 Discovery potential & Sensitivity Reproduce Antares & IC22 where one experiment dominates Reproduce Antares & IC22 where one experiment dominates Coherent limit for whole sky Coherent limit for whole sky Factor 2 gain for specific declinations Factor 2 gain for specific declinations 90% C.L. sensitivity Combined IC22 Antares 5 sigma discovery CLs method used here

Selected source list Start with source lists as specified in Antares & IceCube papers Start with source lists as specified in Antares & IceCube papers Recalculate individual flux limits Recalculate individual flux limits Compare to combined flux limits Compare to combined flux limits 34

Results : selected source lists Important improvement for limits on Southern hemisphere when combining samples Important improvement for limits on Southern hemisphere when combining samples Marginal effect on Northern hemisphere Marginal effect on Northern hemisphere ANTARES ANT & IC22-UHE IC22 ANT & IC22(UHE) ANTARES source list IC22 & IC22-UHE source list

Fullsky search Clustering Clustering Individual setIndividual set at least 4 events within 3 degrees at least 4 events within 3 degrees Combining setsCombining sets At least one 1 per set within 3 degrees At least one 1 per set within 3 degrees Fit Fit 3 parameters within 5-10 degrees3 parameters within 5-10 degrees 36

Fullsky search - South ANTARES ANTARES Event within 3 degrees: 5 Ra Dec Signal events 3.4 Lambda 8.1 Confirmed from Antares Paper Ra Dec Signal events 3.4 Lambda 6.8 Combined Combined Event within 3 degrees: 4 Ant + 4 IC22-UHE Ra Dec Signal events 4.6 Lambda 8.0 Find new cluster ! Compatible with background

Fullsky search - North IC22 IC22 Event within 3 degrees: 14 Ra Dec Signal events 9.5 Lambda 6.4 Different from IC22 Paper Ra Dec 11.4 Signal events 7.7 gamma Combined Combined Event within 3 degrees: 1 Ant + 14 IC22 Ra Dec Signal events 9.5 Lambda 6.2 Find same cluster ! Compatible with background

ANTARES Effective areas Here both plots from PointSource analysis Here both plots from PointSource analysis 50/50 average between neutrino and anti-nu 50/50 average between neutrino and anti-nu Public plots ? Public plots ? 39 ANTARES BBfit 15º bands Full sample 2008 only

Response functions 40 E^-2 flux per half a decade, 2007&2008 E^-2 flux per half a decade, 2007&2008 Number of events per bin for reference flux Number of events per bin for reference flux 10 declination bands (15º each) 10 declination bands (15º each) BBfit (Moscow)AAfit (Claudio)

ANTARES versus IC40 differential sensitivities 41 Dashed: IceCube, Full: ANTARES Half decade bins 5 sigma discovery potential

ANTARES versus IC40 Southern hemisphere only 42 Dashed: IceCube, Full: ANTARES Half decade bins 5 sigma discovery potential

Summary Northern hemisphere Northern hemisphere Only marginal impact of ANTARESOnly marginal impact of ANTARES Southern hemisphere Southern hemisphere Interesting efficiency gainInteresting efficiency gain Improved limitsImproved limits Enhanced potential for fluxes softer than E^-2Enhanced potential for fluxes softer than E^-2 43

Next steps Wait for stable results from individual experiments Wait for stable results from individual experiments ANTARES ANTARES 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 phenomena Look at transient phenomena 44

Public Data