Comparability and Presentation of Results: IceCube

1. Comparability and Presentation of Results: IceCube Chad Finley Oskar Klein Centre Stockholm University Sept. 26, 2009 -- ANTARES IceCube Symposium, Berlin

2. Chad Finley

3. Maximum likelihood analysis performed “everywhere,” i.e. on a finely spaced grid (0.25°×0.25° or 0.1°×0.1°) • Significance estimated analytically for each direction, and shown in plot • Large number of trials, scanning over sky. The final significance of any spot—including the “hottest” spot—is given by the fraction of scrambled data skymaps which have an even hotter spot by chance somewhere in the sky. Chad Finley

4. For a short list of interesting directions selected a priori, we give more details: best fit signal flux, significance, and flux upper limit. Similar to all sky search, we give final significance for “hottest” source on list using scrambled data sets to determine the chance for the list to contain an equal or more significant source. Chad Finley

5. Primary purpose of having an a priori list: to boost the significance of an excess if it occurs in a favored direction (typically, 3σ result in all sky search would be ~ 5σ in list search). Secondary purpose: report flux upper limits (or flux measurements!) for interesting source directions. Note: a priori selection only needs to be done for unbiased significance estimation for claiming a discovery. Upper limits can be reported for any direction in sky, no a priori selection needed Chad Finley

6. How to present measurements/upper limits for the whole sky? For AMANDA, skymap of flux upper limits worked well: Skymap of νµ + ντ 90% confidence level flux upper limits for an E−2 energy spectrum (10−11 TeV cm−2 s−1) over the energy range 1.9 TeV to 2.5 PeV [Phys.Rev.D79:062001,2009] For IceCube, does not work so well: Sensitivity is much steeper function of declination… plot is dominated by this gradient rather than map structure. Chad Finley

7. Jim Braun et al., Astropart.Phys.29:299-305,2008 There is a lot of information still “hidden” at each point, including a different upper limit for each possible model spectrum. 2D confidence level contours for signal strength vs. spectral index can be calculated for any direction. This could work as an online tool, for example, provided to the community as an interface to the skymap. Upper limit Chad Finley

8. Standard plot of point source sensitivity as a function of declination, for E^-2 spectrum Median upper limits (scrambled data sets used to find median value of upper boundary of 90% Feldman Cousins confidence interval, including systematics, following Conrad, J., Botner, O., Hallgren, A., & Perez de los Heros, C. 2003, Phys. Rev. D, 67, 012002; Hill, G. C. 2003, Phys. Rev. D, 67, 118101) Chad Finley

9. +75° +60° +45° +30° -log10 p +15° 24h 0h

10. +75° +60° +45° +30° +15° 24h 0h -15° -30° -45° -log10 p -log10 p R. Lauer, Heidelberg Workshop, Jan09 arXiv:0903.5434

11. IC40 first 6-months (J. Dumm et al., ICRC 2009) Chad Finley

12. IC40 first 6-months (J. Dumm et al., ICRC 2009) E^-2 sensitivity of IceCube-40 crosses ANTARES at dec -30° ! In reality, very different energy ranges… Chad Finley

13. Construction of Differential Sensitivity Curve • Each line represents sensitivity to E^-2 neutrino signal for energy range given by length of line. • [technically, IC22 5  sensitivity for E-2 source at  = +6°] All curves for source at  = +6° Chad Finley

14. Construction of Differential Sensitivity Curve • Connect lines with a curve for readability Chad Finley

15.  = +30°  = +60° • IC40 Differential 5 Discovery Potentials • Northern Sky  = +6° Chad Finley

16.  = +30°  = -60°  = -30°  = -8°  = +60° • IC40 Differential 5 Discovery Potentials • Northern and Southern Sky  = +6° Chad Finley

17.  = -30° ANTARES ? Chad Finley

18.  = -30° ANTARES ? Can have same integrated E^-2 sensitivity curves; different energy ranges Chad Finley

19.  = +30°  = -60°  = -30°  = -8° ANTARES ?  = +60° Crab =+22° • Predicted neutrino fluxes for a few selected sources  = +6° 3C279 =-6° MGRO J1908 =+6° Chad Finley

20.  = +30°  = -60°  = -30°  = -8° ANTARES ?  = +60° Crab =+22° • Predicted neutrino fluxes for a few selected sources • And IC40 approximate sensitivity to sources according to flux model and declination  = +6° 3C279 =-6° MGRO J1908 =+6° Chad Finley

21. Diffuse Models Chad Finley

22. Diffuse Sensitivity Chad Finley

23. Presentation: • Standard presentation—skymap, source list, p-value of hottest spot or source—is natural for presenting results aimed at discovery. • Great deal of additional information remains “hidden,” but technically has been unblinded and should be reportable. • Long-term strategy: tools for presenting multi-dimensional (e.g. flux, spectral index) full confidence intervals for any direction… make available online one day? • Comparability: • Sensitivity is strong function of energy and—for point sources—declination. • One-dimensional curves not enough – can give misleading impression that sensitivities overlap when energy ranges are actually quite different. • Differential sensitivity curves help to clarify energy dependence that is hidden in integrated and E- sensitivity calculations. • Still looking for a more compact solution for point sources! For now, we must take care to keep energy ranges in mind when making any comparisons. Chad Finley

24. Extras

25. E-2 E-1.5 • Southern Sky Northern Sky Southern Sky Northern Sky Chad Finley

26.  = +30°  = -60°  = -30°  = -8°  = +60°  = +6° E-1.5 Chad Finley

27.  = -8°  = -30°  = -60°  = +30°  = +60° E-1.5  = +6° Chad Finley

28. Chad Finley

29.  = +30°  = -60°  = -30°  = -8°  = +60°  = +6° Chad Finley

30.  = +30°  = -60°  = -30°  = -8°  = +60° Crab =+22°  = +6° 3C279 =-6° MGRO J1908 =+6° Chad Finley

31. Crab =+22° • IC22, IC40 sensitivities for three sources 3C279 =-6° MGRO J1908 =+6° Chad Finley

32. Chad Finley

33. Chad Finley