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Lessons from IceCube & KM3NeT: Multi-Wavelength Point Source Searches

Explore Lessons from IceCube & KM3NeT collaborations, network of opportunity projects with formal questions on detector optimization, sensitivity factors, and software cooperation. Detailed insights on spacing exercises & signal expectations for best sensitivity.

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Lessons from IceCube & KM3NeT: Multi-Wavelength Point Source Searches

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  1. Connections IceCube – KM3NeT Christian Spiering DESY

  2. Content • Lessons from IceCube • „Multi-wavelength“ point source searches • Network of Target of Opportunity projects • Other coordinated efforts • Cooperation on software and algorithms • Formal questions

  3. Lessons from IceCube (and from theoreticians) • How big a detector ? • Optimization to which energy range ? • Which configuration ?

  4. How big a detector ? • KM3NeT: „Substantially more sensitive than IceCube“ • Point sources: factor ~2 from angular resolution alone • This is by far not enough in case IceCube would not have identified sourcesin 2010/11 • Need something like the „canonical factor 7“ • LHC  LHC upgrade (in luminosity) • 50 kt Super-K  300 kt DUSEL/Hyperkam (in volume) • Auger-South  Auger North (in area) •  Need much more than a cubic kilometer in volume !!

  5. Early IceCube spacing exercises • Increasing the string spacing from 100 to 180 m increases: • volume by factor 3 • 5 sensitivity by 40% • We have been reluctant to go to the largest spacing since: • String-to-string calibration may work worse. • Due to light scattering in ice the sensitivity increases much weaker than the area for large spacing. • We were optimistic w.r.t. the signal expectation. IceCube: 125 m E-2

  6. Early IceCube spacing exercises • Increasing the string spacing from 100 to 180 m improves: • volume by factor 3 • 5 sensitivity by 40% • We have been reluctant to go to the largest spacing since: • String-to-string calibration may work worse. • Due to light scattering in ice the sensitivity increases weaker than the area for very large spacing. • We were optimistic w.r.t. the signal expectation. IceCube: 125 m Would be no concern today Not important in water Too optimistic

  7. Threshold for best sensitivity 1 cubic kilometer IceCube Diffuse E-2 flux Blue: after downgoing muon rejection Red: after cut for ultimate sensitivity

  8. Threshold for best sensitivity 1 cubic kilometer IceCube Point sources (E-2) Blue: after downgoing muon rejection Red: after cut for ultimate sensitivity

  9. Threshold for best sensitivity Point sources Several cubic kilometers (educated guess) Threshold between 3 and 5 TeV ! Blue: after downgoing muon rejection Red: after cut for ultimate sensitivity

  10. Ceterum censeo: • Optimize to energies > 5 TeV, even if you have to sacrifice lower energies! • See original GVD/Baikal with muon threshold ~ 10 TeV (but, alas, < 1 km³) 208m 624m 70m 70m 120m 280m

  11. Expected n flux from galactic point sources, example: RXJ 1713-3946 (see also Paolo Lipari’s talk) Assume p0 g and calculate related p±  n C. Stegmann ICRC 2007

  12. Milagro sources in Cygnus region Halzen, Kappes, O’Murchadha Probability for fake detection: • 6 stacked sources • Assumption: cut-off at 300 TeV • p-value <10-3 after 5 years • Optimal threshold @ 30 TeV (determined by loss of signal events)

  13. Aharonian, Gabici etc al. 2007 atmospheric neutrinos (green) vs. source spectra with - different spectral index (no cut-off) - index = 2 and cut-off at 1 and 5 PeV. normalized to dN/dE (1 TeV) = 10-11 TeV-1 cm-2 s-1

  14. Aharonian, Gabici etc al. 2007 atmospheric neutrinos (green) vs. source spectra with - different spectral index (no cut-off) - index = 2 and cut-off at 1 and 5 PeV. normalized to dN/dE (1 TeV) = 10-11 TeV-1 cm-2 s-1

  15. What about the low energies when increasing the spacing? • Instrumenting a full cubic kilometer with small spacing is not efficient since for low fluxes a further increase of the low energy area will yield low-energy signal rates which are much lower than the atmospheric neutrino background rates. • Better: a small nested array with small spacing – enough to „exhaust“ the potential at low energy. • Don‘t distribute the small spacing areas over the full array but concentrate it in the center • Better shielding • No empty regions • Better performance for contained events • … • DeepCore!

  16. IceCube with DeepCore

  17. IceCube with DeepCore VETO low-energy nested array

  18. Early IceCube Exercises

  19. The present Baikal scenario L~ 350 m R ~ 60 m 12 clusters of strings NT1000: top view

  20. Compare to KM3NeT scenarios: a b c d

  21. Content • Lessons from IceCube • „Multi-wavelength“ point source searches • Network of Target of Opportunity projects • Other coordinated efforts • Cooperation on software and algorithms • Formal questions

  22. If  telescopes would be only sensitive up to horizon …. IceCube „blind“ Antares Baikal KM3NeT „blind“

  23. … resulting in: point source limits/sensitivities • Overlap region 25% • at any given moment, • 70% of IceCube sky • seen by KM3NeT at • some moment.

  24. Actually you can look above horizon for higher energies: +75° +60° +45° +30° +15° 24h 0h -15° +15° -30° 24h -log10 p 0h -45° -log10 p R. Lauer, Heidelberg Workshop, Jan09 arXiv:0903.5434 IceCube 22 strings, 2007

  25. Actually you can look above horizon for higher energies: +75° +60° +45° +30° +15° 24h 0h -15° -30° -45° +15° 24h -log10 p 0h -log10 p IceCube 22 strings, 2007

  26. Actually you can look above horizon for higher energies: IceCube 40 strings 6 months 2008

  27. Differential IceCube sensitivity to point sources(IC-40, 1 year, 5 discovery potential, normalized to ½ decade) Taken from Chad Finley, MANTS  = +30°  = +60°  = +6° TeV PeV

  28. Differential IceCube sensitivity to point sources(IC-40, 1 year, 5 discovery potential, normalized to ½ decade) Taken from Chad Finley, MANTS  = +30°  = -60°  = -30°  = -8°  = +60°  = +6° TeV PeV

  29. Spectral form for extra-galactic sources Multi-wavelength analysis of individual sources ?  = +30°  = -60°  = -30°  = -8°  = +60°  = +6° Blazars Stecker 2005 GRB-precursor Razzaque 2008 WB prompt GRB BLacs Mücke et al 2003 3 4 5 6 7 8 9 TeV PeV

  30. Compare to absolute predictions Taken from Chad Finley, MANTS  = +30°  = -60°  = -30°  = -8°  = +60° Crab =+22°  = +6° 3C279 =-6° MGRO J1908 =+6° • Predicted neutrino fluxes for a few selected sources (full lines) • IC40 approximate 90% CL sensitivity to sources according to flux model and declination (dashed lines)

  31. Multi-wavelength/full sky analysis • Cover 4 with 2 detectors  full sky map • Add evidences/limits in overlap regions • Combine TeV-PeV information from lower hemisphere of one detector with PeV-EeV information from upper hemisphere of the other detector  multiwavelength analysis over 3-5 orders of magnitude in wavelength / energy. • Need: • Coordinated unblinding procedures • Coordinated candidate source list (also for source stacking) • Point spread functions • Effective areas as function of energy

  32. Alert Programs • GRB information from satellites • offline analysis, online: storage of unfiltered data & high efficiency at low E (like Antares) • Optical follow-up:  telescopes  robotic optical telescopes • Gamma follow-up (NToO):  telescopes  Gamma telescopes • Supernova burst alert: IceCube (also KM3NeT? ) • Arguably, the ratio of signal to background alerts from  telescopes is an issue. Alert programs have to be coordinated worldwide, be it only not to swamp optical/gamma telescopes with an unreasonable number of alerts.

  33. Optical Follow-Up

  34. Antares Optical follow-up

  35. „Neutrino Target of Opportunity“

  36. Alert Programs • GRB information from satellites • offline analysis, online: storage of unfiltered data & high efficiency at low E (like Antares) • Optical follow-up:  telescopes  robotic optical telescopes • Gamma follow-up (NToO):  telescopes  Gamma telescopes • Supernova alert (IceCube) • IceCube triggers KM3NeT and vice versa ? Test: Antares  IceCube

  37. Presentation of WIMP results • Classes of tested models • Presentation of model parameter space • Comparison with direct searches

  38. Other examples • GRB stacking • Combine KM3NeT/IceCube GRB lists, increasing the overall sensitivity • Diffuse fluxes Any - high energy excess (extraterrestrial or prompt ) - high energy deficit (QG oscillations) should be confirmed by an independent detector, with different systematics • Confirmation of exotic events • Slowly moving particles (GUT monopoles, Q-balls, nuclearites)  artefacts or reality?

  39. Software and algorithms MoU between IceCube and KM3NeT summer 2008 Framework: IceTray  KM3Tray  SeaTray (now official software framework for ANTARES and KM3NeT) Improvements, debugging KM3NeT  IceCube Modules (future): KM3NeT  IceCube Simulation (event generators, air showers,…) Reconstruction methods Use of waveforms Basic algorithms (like - already now – Gulliver fitting)

  40. Content • Lessons from IceCube • „Multi-wavelength“ point source searches • Network of Target of Opportunity projects • Other coordinated efforts • Cooperation on software and algorithms • Formal questions

  41. Formal framework • Memoranda of Understanding on specific items • like that on IceTray • Yearly common meetings • Similar to the one we had in Berlin (MANTS) • Inter-collaboration working groups which • „synchronize“ statistical methods, ways of presentation, simulations, … (for point sources, diffuse fluxes, dark matter, …) • Global Network ? • Like LIGO/Virgo/GEO • Global Neutrino Observatory, with inter-collaboration committees ? • like Auger, CTA

  42. Formal framework • Memoranda of Understanding on specific items • like that on IceTray • Yearly common meetings • Similar to the one we had in Berlin (MANTS) • Inter-collaboration working groups which • „synchronize“ statistical methods, ways of presentation, simulations, … • for point sources, diffuse fluxes, dark matter • Global Network ? • Like LIGO/Virgo/GEO • Global Neutrino Observatory, with inter-collaboration committees ? • like Auger, CTA Could start this with the full community (IceCube, Antares/KM3NeT, Baikal)

  43. A global network ? KM3NeT GVD IceCube

  44. But first of all …. … let IceCube* try to do the best it can do for KM3NeT: …see a first source ! * and ANTARES. Who knows ?

  45. Acknowledement • Part of this talk is based on talks given at the • MANTS Meeting, September 2009, in Berlin. • Special thanks to: • Teresa Montaruli • Jürgen Brunner • Chad Finley • Tom Gaisser, Uli Katz, Francis Halzen

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