IC-22 Point Source Analysis with Unbinned Maximum Likelihood C. Finley, J. Dumm, T. Montaruli 2008 May 2

2008 MadisonC. Finley2 Overview 1.Basic Set of Cuts for point-source quality sample using Level 2 processing 14 days ( 12.6 days livetime) of Level 2 Filtered data  (Sept. 14, 15, 16, 17, 18, 20, 21, 22, 23, 24, 25, 27, 28, 29) 1000 files of Level 2, muon-filter Nugen E -1 (optimal for E -2 source sim.)  Dataset files of Level 2, muon-filter Nugen E -2 (optimal for high statistics AtmNu)  Dataset First look at adding energy term to the likelihood in IC-22 (similar to method of J. Braun for AMANDA-II)

2008 MadisonC. Finley3 Muon Filter + Pandel Zenith>90 Cut

2008 MadisonC. Finley4 Paraboloid Sigma Cut

2008 MadisonC. Finley5 Pandel Reduced Log Likelihood Cut

2008 MadisonC. Finley6 Split Hit Series Cut: Pandel zen1>80 and zen2>80

2008 MadisonC. Finley7 NDirC Cut

2008 MadisonC. Finley8 Pandel SDir Cut

2008 MadisonC. Finley9 Maximum Likelihood Analysis Part I: Point Spread Function By now the maximum likelihood expression is familiar for point source searches: where the source PDF is a Gaussian with width given by the paraboloid sigma uncertainty estimate: and the background PDF depends only on zenith angle:

2008 MadisonC. Finley10 Sensitivity with Analysis-Level Cuts E -2 average sensitivity  0 = 1.7  TeV -1 cm -2 s -1 Preliminary IC-22 Sensitivity for 250 d ( ~ 20 atmNu events per day )

2008 MadisonC. Finley11 Sensitivity with Analysis-Level Cuts E -2 average sensitivity  0 = 1.7  TeV -1 cm -2 s -1 IC-9 Sensitivity IC22 Sensitivity

2008 MadisonC. Finley12 Sensitivity with Analysis-Level Cuts E -2 Sensitivity est. from Gent meeting, based on atmNu background simulation only E -3

2008 MadisonC. Finley13 Maximum Likelihood Analysis Part II: Energy Now, want to add energy term to the Likelihood function, to weight higher energy events with greater significance:

2008 MadisonC. Finley14 Maximum Likelihood Analysis Part II: Energy Now, want to add energy term to the Likelihood function, to weight higher energy events with greater significance:

2008 MadisonC. Finley15 Energy PDFs Start with simplest energy estimator: NChan P (E i |  =2) P (E i |  =3) P atm (E i )

2008 MadisonC. Finley16 Maximum Likelihood fit to nSrc and Gamma: Examples gamma nSrc Examples: Simulated E -2 source at declination +30° Left: 15 events injected (cross) Right: 30 events injected (cross) 1-sigma and 2-sigma contours are shown for best fit to number of source events nSrc and spectral index gamma

2008 MadisonC. Finley17 Maximum Likelihood fit to nSrc and Gamma: Examples gamma nSrc Below: Simulated E -3 source at declination +30° Left: 15 events injected; Right: 30 events injected 1-sigma and 2-sigma contours are shown for best fit to number of source events nSrc and spectral index gamma

2008 MadisonC. Finley18 Effect of Energy Term on Discovery Potential Simulated E -2 source at declination +30°: 5-sigma Discovery potential (Power 50%): without energy term in likelihood: 6.1  GeV -1 cm -2 s -1 (E/GeV) -2 (mean number of source events: 15 ) with energy term in likelihood: 4.2  GeV -1 cm -2 s -1 (E/GeV) -2 (mean number of source events: 10.5 )

2008 MadisonC. Finley19 Summary Basic cuts on Level 2 parameters and basic maximum likelihood analysis yield point source sensitivity ≈ 7x better from IC-9. Many significant improvements coming soon: Level 3 reconstructions MPE reconstruction: better high energy efficiency, better angular resolution (see talk by J. Dumm) Time residuals of MPE should improve efficiency of NDirect cut (or we may find an alternative cut for best high energy efficiency) Adding energy term to likelihood: Test with new energy estimators in level 3 (better than Nch estimate) Reasonable to expect at least 30% improvement in discovery potential for hard spectra.