Results from the AMANDA Neutrino Telescope

1. Results from the AMANDA Neutrino Telescope CRIS06, Catania, June 2006 Juande D. Zornoza University of Madison-Wisconsin

2. Neutrino CV • Neutral • Stable • Weakly interacting* Neutrino Astronomy High energy astronomy: Which probes can we use? Photon and proton mean free range path *very large detectors needed • Photons interact with the CMB and with matter • Cosmic rays are deflected by magnetic fields and also interact with matter • Neutrons are not stable What else? Oh, yeah, neutrinos!

3. Production Mechanisms • Gamma and cosmic ray astrophysics are deeply related with neutrino astronomy: Cosmic rays Gamma ray astronomy Neutrino flavor rate: e:: ~ 1:2:<10-5 at the source e:: ~ 1:1:1 at the detector

4. Scientific Scopes ? Other physics: monopoles, Lorentz invariance, super-massive DM , SUSY Q-balls, etc...

5. AMANDA/IceCube Collaboration • Bartol Research Institute, Delaware, USA • Pennsylvania State University, USA • UC Berkeley, USA • UC Irvine, USA • Clark-Atlanta University, USA • Univ. of Maryland, USA • IAS, Princeton, USA • University of Wisconsin-Madison, USA • University of Wisconsin-River Falls, USA • LBNL, Berkeley, USA • University of Kansas, USA • Southern University and A&M College, Baton Rouge, USA Japan USA (12) Europe (13) • Chiba university, Japan • University of Canterbury, Christchurch, NZ New Zealand • Universite Libre de Bruxelles, Belgium • Vrije Universiteit Brussel, Belgium • Université de Gent, Belgium • Université de Mons-Hainaut, Belgium • Universität Mainz, Germany • DESY-Zeuthen, Germany • Universität Dortmund, Germany • Universität Wuppertal, Germany • Uppsala university, Sweden • Stockholm university, Sweden • Imperial College, London, UK • Oxford university, UK • Utrecht,university, Netherlands

6. Amundsen-Scott South Pole Station Runway South Pole AMANDA-II

7. 1 km 2 km AMANDA Detector • 1997-99: AMANDA-B10 (inner lines of AMANDA-II) • 10 strings • 302 PMTs • from 2000: AMANDA-II • 19 strings • 677 OMs • 20-40 PMTs / string SPASE At the surface: SPASE • Coincident events • Angular resolution • Cosmic ray composition trigger rate = 80 Hz

8. Signatures CC- interactions: long (~km) tracks NC-and CC-e/ interactions: cascades 15 m (tracks short w.r.t. the inter-OM distance) • Other signatures, like double bang, are expected to be more rare.

9. p      p Background • There are two kinds of background: • -Muons produced by cosmic rays in the atmosphere (→ detector deep in the ice and selection of up-going events). • -Atmospheric neutrinos (cut in the energy, angular bin…).

10. Ice Properties • Shorter scattering length than in sea, but longer absorption length (larger effective volume): Average optical ice parameters: labs ~ 110 m @ 400 nm lsca ~ 20 m @ 400 nm Absorption Scattering ice bubbles dust dust Moreover, very “silent” medium: dark noise < 1.5 kHz

11. signal bin background estimation Event reconstruction • The position, time and amplitude registered by the PMTs allows the reconstruction of the track, using Likelihood optimization techniques. • The angular resolution depends on the quality cuts of each specific analysis. For instance, in the point-like source search, it is 2.25-3.75 deg (declination dependent). • Once reconstructed the positions of the tracks, we can compare the number of events in each signal bin with the background at that declination. example of AMANDA event

12. ~92% Sky map 2000-2003 (807 days) 3329 ns detected from Northern Hemisphere 3438 atmospheric ns expected The largest fluctuation (3.4) is compatible with atmospheric background

13. AMANDA-B10 average flux upper limit [cm-2s-1] AMANDA-II sin(d) Performance Neutrino Effective Area Sensitivity to E-2 Point-like sources Ndet=Aeff × Time × Flux • Sensitivity: Average upper limit, integrated above 10 GeV. • Steady increase with time. • For E<10 PeV, Aeff grows with energy due to the increase of the interaction cross section and the muon range. • For E>10 PeV the Earth becomes opaque to neutrinos.

14. AGNs: Stacking source analysis • Neutrino astronomy could be the key for establishing the hadronic/leptonic origin of the HE photons from AGNs. • Stacking-source analysis: The flux from AGNs of the same type integrated to enhance the statistics. preliminary single source sensitivity (four years) • No significant excess has been found. • The stacking approach improves the one source limit by a factor three, typically.

15. Multi-wavelength approach • Transient events also provide an opportunity to enhance sensitivity • We can look for correlations with active periods from electromagnetic observations: • Blazars: X-rays • Microquasars: radio 2000-03 data sources: TeV blazars, microquasars and variable sources from EGRET

16. Transient sources • When the variable character of the source is evident, but the EM observations are limited, we can use the sliding-window technique. • For the time-rolling source search, events in a sliding time window are searched: • Galactic: 20 days • Extragalactic: 40 days Extragalactic Galactic sources: TeV blazars, microquasars and variable sources from EGRET

17. Orphan Flare • Three events in 66 days within the period of a mayor 1ES 1959+650 burst (orphan flare:s but no X-rays) • A posteriori search  undefined probability of random coincidence. sliding search window

18. Diffuse fluxes • Atmospheric neutrino spectrum is reconstructed using regularization-unfolding techniques. • No extraterrestrial diffuse component has been observed. E2 d/dE = 1.1 x 10-7 GeV cm-2 s-1 sr-1(over the range 16 TeV to 2 PeV)

19. UHE neutrinos (I) • UHE neutrinos (>106 GeV) can be produced in several scenarios (AGNs, topological defects, GZK…) • >107 GeV the Earth is opaque to neutrinos  search for horizontal tracks. • Background: muon bundles from atmospheric showers. • Neural network trained to distinguish between signal and background simulated UHE event

20. UHE neutrinos (II) • Signal versus background: • Signal produces higher light density • There are more hits in UHE single muons, due to the after-pulsing in the photomultipliers. • Background events are produced mainly vertically down-wards and signal events are expected to be horizontal. • Different residual time distributions (because of after-pulsing) • Center of gravity of hits pulled away from the geometrical center of the detector for down-going bundles.

21. UHE neutrinos (III) • 2000 data used for this analysis: • 20% for the optimization of cuts • 80% after unblinding is approved • There is a factor two of improvement in the sensitivity w.r.t. AMANDA B10 Limit = 3.710-7 GeV cm-2 s-1 sr-1 (from 1.8105 to 1.8109 GeV)

22. UHE neutrinos (IV) • PRELIMINARY sensitivities to different models of UHE production: L. Gerhardt

23. 0.4 s SGR 1806-20 The SGR 1806-20 flare (Dec. 2004) was more than one order of magnitude more powerful (2x1046 erg) than previous flares: detectors saturated. RA (J2000) 18h 08m 39.4s = 272.16 deg DEC (J2000) -20deg24'39.7" = -20.41 deg Duration < 0.6 s + Time window 1.5 s Swift-BAT light curve We try to observe down-going muons produced by TeV photons discriminating the background of atmospheric muons using an angular and a time window

24. SGR 1806-20 Discovery • Optimum cone size: 5.8° • Best MDF: 2.3 • Observed events needed: 4 • Background: 0.06 5 events, time window: 1.5 s Confidence interval=5 Statistical Power=90% • MDF have jumps when we have to increase the (discrete) number of events needed to satisfy the condition of 5 confidence interval. • MRF behaves smoothly since only the mean expected background in taken into account.

25. SGR 1806-20 • Unfortunately, no event was found after unblinding, so upper limits have been calculated. Effective areas Limit in flux normalization neutrinos preliminary gammas • Limits in the constant of a d/dE=A E-1.47 flux are set, constraining both the HE gamma and neutrino emission.

26. GRBs (average spectrum) • Search time window: from 10 sec before the burst start to the end of the burst. • Precursor: from -110 sec to -10 sec. • Background estimation: from 1 hour before to 1 hour after (except 10 minutes around the burst which remain unblinded)

27. Neutralino Search  • WIMPs would scatter elastically in the Sun or Earth and become gravitationally trapped. • They would annihilate producing standard model particles. • Among the annihilation products, only neutrinos can reach us. • Neutralinos annihilate in pair-wise mode: ann: annihilation rate per unit of volume ann: neutralino-neutralino cross-section v: relative speed of the annihilating particles : neutralino mass density m: neutralino mass and neutrinos are produced as secondaries.

28. Neutralino Search excluded by Edelweiss The Sun is the most promising source of neutralinos. Neutralino density in the Earth is diminished the effect of the Sun mass.

29. Conclusions • AMANDA has been operating for almost one decade. • No extraterrestrial neutrino has been observed above the atmospheric background, • Increasingly stringent limits have been set in point-like sources, diffuse fluxes, neutralinos… • A bigger detector is needed  IceCube (already in construction!) YET… but sometimes success comes after much work and patience! Thanks to the organizers!

30. Backup transparencies

31. Particle Physics

32. Monopoles • Monopoles would also give a large signal in the detector, which can be discriminated from high energy muons. • Two signatures are possible: • Direct emission (βm>0.74): ×8500 wrt muon • Induced δ-ray emission (βm>0.51)

33. b b-2 a GRB model parameterization

34. Model Sensitivity (GeV s-1 cm-2) Limit (GeV s-1 cm-2) isotropic (1) 0.157 0.150 beamed (2) 0.041 0.039 average (WB) (3) 0.036 0.035 GRBs (individual spectrum) • The individual spectrum can be used instead of the average to enhance the sensitivity for a given burst. • The parameters of the Band function of the GRB030329 burst were calculated. neutrino energy flux (GeV cm-2 s-1) 1 2 3

35. GRBs: individual bursts

36. AGN models • Low energy (from radio up to UV / X-ray): non-coherent synchrotron radiation. • High energy (up to TeV) under debate: leptonic versus hadronic models.