Neutrino Astronomy at the South Pole: Latest Results and Future of IceCube

1. Neutrino Astronomy at the South PoleLatest results from AMANDA and perspectives for IceCubePaolo Desiatidesiati@icecube.wisc.eduUniversity of Wisconsin – Madison 20th International Workshop on Weak Interactions and Neutrinos (WIN'05) http://amanda.uci.edu http://icecube.wisc.edu

2. Who is in IceCube ? Bartol Research Inst, Univ of Delaware, USA Pennsylvania State University, USA University of Wisconsin-Madison, USA University of Wisconsin-River Falls, USA LBNL, Berkeley, USA UC Berkeley, USA UC Irvine, USA Univ. of Alabama, USA Clark-Atlanta University, USA Univ. of Maryland, USA IAS, Princeton, USA University of Kansas, USA Southern Univ. and A&M College, Baton Rouge, LA, USA Institute for Advanced Study, Princeton, NJ, USA Chiba University, Japan University of Canterbury, Christchurch, New Zealand Université Libre de Bruxelles, Belgium Vrije Universiteit Brussel, Belgium Université de Mons-Hainaut, Belgium Universiteit Gent, Belgium Universität Mainz, Germany DESY-Zeuthen, Germany Universität Wuppertal, Germany Universität Dortmund, Germany Humbolt Universität, Germany Uppsala Universitet, Sweden Stockholm Universitet, Sweden Kalmar Universitet, Sweden Imperial College, London, UK University of Oxford, UK Utrecht University, Netherland Amundsen-Scott Station, Antarctica

3. Where are we ? IceCube South Pole Dome road to work AMANDA Summer camp 1500 m Amundsen-Scott South Pole Station 2000 m [not to scale]

4. “Up-going” (from Northern sky) “Down-going” (from Southern sky) AMANDA-B10 (inner core of AMANDA-II) 10 strings 302 OMs Data years: 1997-99 AMANDA-II 19 strings 677 OMs Trigger rate: 80 Hz Data years: >=2000 Optical Module PMT looking downward PMT noise: ~1 kHz

5. First year deployment (Jan 2005) 1 IceCube string (60 OMs) 8 IceTop Tanks (16 OMs) IceTop 160 tanks frozen-water tanks 2 OMs / tank 1200 m IceTop IceCube AMANDA IceCube 80 strings 60 OMs/string 17 m vertical spacing 125 m between strings 10” Hamamatsu R-7081

6. <labs>~ 110 m @ 400 nm <lsca>~ 20 m @ 400 nm Event detection in the ice O(km) long mtracks South Pole ice: the most transparent natural medium ? event reconstruction by Cherenkov light timing ~17 m • AMANDA-II • mtracks • pointing error : 1.5º - 2.5º • σ[log10(Eμ/TeV)] : 0.3 - 0.4 • coverage : 2p • Cascades (particle showers) • pointing error : 30º - 40º • σ[log10(Ec/TeV)] : 0.1 - 0.2 • coverage : 4p • cosmic rays (+SPASE) • combined pointing err : < 0.5º • σ[log10(Ep/TeV)] : 0.06 - 0.1 • Nucl. Inst. Meth. A 524, 169 (2004) cascades a neutrino telescope Qmn0.65o(En/TeV)-0.48 (3TeV<En<100TeV) Longer absorption length → larger effective volume

7. Array AMANDA IceCube ν astronomy : physics goals Bottom-Up scenario cosmic accelerator p + (p or )   + X  e ,+ X Energy  Eν-2(fermi acceleration) Atm. ν Eν-3.7(energy separation) • Still no evidence of TeV  detection from oproduction • Neutrino detection would demonstrate hadronic processes • steady and transient point sources (point resolution) • unresolved faint neutrino sources (diffuse ν) • expected extraterrestrial ν require km3 scale detectors ! • background rejection • good acceptance • high sensitivity • Protons which escape are • bent => cosmic rays • Photons which escape are • absorbed above 50 TeV • Neutrinos escape

8. ν astronomy : background Background rejection Cosmic ray μmain background (statistical errors) data/mc ~ +30% normalized • Protons which escape are • bent => cosmic rays • Photons which escape are • absorbed above 50 TeV • Neutrinos escape Preliminary

9. Preliminary ν astronomy : background Atmospheric nm background & calibration beam First energy spectrum > 10 TeV Blobel regularized unfolding Expected high energy nm flux importance of high energy prompt leptons background from charm still uncertain • Protons which escape are • bent => cosmic rays • Photons which escape are • absorbed above 50 TeV • Neutrinos escape

10. n telescope : AMANDA event energy deposited in OM time recorded on OM

11. signal bin background estimation n telescope : point source search • Detection of nm from discrete steady bright or close sources (AGN, …) • binned optimization in δ bands, versus a given signal hypothesis ( E-2) • cosmic ray μbackground rejection • good pointing resolution (good quality events) • possible event-energy selection • background estimated from exp data with randomized α(i.e. time) • signal obtained from full simulation • obtain best sensitivity (average upper limit)

12. AMANDA-II - 2000-02 (607 days) 1 m2  d=0o  d declination d=90o  n telescope : point source search Detection of nm from discrete steady bright or close sources (AGN, …)

13. 1997 : ApJ 583, 1040  (2003) 2000 : PRL 92, 071102 (2004) 2000-02 : PRD 71 077102 (2005) IceCube : Astrop Phys 20, 507 (2004) * AMANDA-B10 average flux upper limit [cm-2s-1] average flux upper limit [cm-2s-1] AMANDA-B10 AMANDA-II AMANDA-II IceCube 1/2 year d=0o  d declination d=90o  sin(d) sin(d) n telescope : point source search Average upper limit = sensitivity (δ>0°) (integrated above 10 GeV, E-2 signal) (*)optimized for E-2, -3signal * Sensitivity independent of direction increases almost linearly with exposure lim  0.68·10-8 cm-2s-1 Preliminary

14. n telescope : point source search PRD 71 077102 (2005) AMANDA-II - 2000-02 (607 days)

15. Maximum significance 3.4 s compatible with atmospheric n ~92% n telescope : point source search Preliminary • Search for clustering in northern hemisphere • compare significance of local fluctuation to • atmospheric n expectations • un-binned statistical analysis • no significant excess 2000-2003 (807 days) 3329 n from northern hemisphere 3438 n expected from atmosphere also search for neutrinos from unresolved sources

16. n telescope : unresolved sources ? • neutrinos from single steady sources may be as many as background • enhance detection using: • stacking steady point source candidates (on the way) • catalogue of possible neutrino emitter AGN candidates and selection optimization on the ensamble to enhance sensitivity • time correlation with transient phenomena (preliminary results) • known active flary periods of TeV gamma sources • time-rolling search of signal excess over background • diffused flux of neutrinos with no time-space correlations (preliminary results) • calculate upper limit on high energy tail of atmospheric νμ • optimize selection with attention to background(s) rejection • multi-flavor (muon tracks + cascades)

17. n telescope : point source search • Detection of nm from known active flary periods • periods (during 2000-03) and sources selected on the basis of the available multi-wavelength information • the wavelengths investigated are possible indicators for a correlated neutrino emission (X-ray for Blazars and radio for Microquasars) • based on hypothesis neutrinos are emitted in coincidence with electromagnetic flare emissions

18. sliding window events time n telescope : point source search Detection of nm with time rolling search • time window: 40 / 20 days for Extragalactic / Galactic Objects • angular bin: 2.25°-3.75°

19. n telescope : diffused sources • no space-time correlation which helps in rejecting background • signal hypothesis with harder energy spectrum than background (Fermi acceleration) • requires good understanding of background(s) • requires detector systematics to be under control • relies on simulation of background and signal events • sensitivity to high energy tails (up to ~ PeV)  E-3.7  10-6× E-2 # hit Optical Modules

20. n telescope : diffused sources νμ: 2π coverage • energy reconstruction with NN • acceptance correction with regularized Blobel unfolding • confidence interval construction according to FC prescription • set upper limit on last bin • ΦνE2 < 2.6 × 10-7 GeV cm-2s-1sr-1(100 TeV < E < 300 TeV) • extending to longer exposure (2000-03) year 2000 Preliminary • optimization on observables for background rejection and event quality • energy estimator is the number of hit OM • best expected sensitivity (2000-03) : ΦνE2 <9 × 10-9 GeV cm-2s-1sr-1(10 TeV < E < 5 PeV)

21. νe signal background no earth propagation effects nt nm Nobs = 1 event Natm μ = 0.90 Natm ν = 0.06 ± 25%norm ne +0.69 -0.43 +0.09 ­0.04 n telescope : diffused sources Cascades: 4π coverage year 2000 Astroparticle Physics 22 (2004) 127 After optimized cuts: E ~160 TeV

22. n telescope : diffused sources UHE: 4π coverage • Earth opaque to PeV neutrinos → look up and close to horizon • Look for very bright events (large number of Optical Modules with hits) • Train neural network to distinguish E-2 signal from background year 1997 (AMANDA-B10) Astroparticle Physics 22 (2005) 339 Simulated UHE event Nobs = 5 events Nbgr = 4.6 ± 36% events ΦνE2 < 0.99·10–6 GeV cm-2 s-1 sr-1 (1 PeV < E < 3 EeV)

23. n telescope : diffused summary cascade (B10 1yr) x3 diffuse (B10 1yr) UHE (B10 1yr) • limits on all-flavor • limits on E-2 • would need to model • other spectra all-flavor limits cascade (A-II 1yr) diffuse (A-II 1yr) diffuse (A-II 4yr)

24. n telescope : Galactic Plane • interaction of CR in interstellar medium expected to produce a flux of neutrinos from the galactic disk • same energy spectrum as CR  E-2.7 • modelled πo component of γ rays in 4GeV < E < 10GeV has σ~2.1o in galactic latitude (Strong et al., ApJ 613, 2004) • AMANDA-II angular resolution ~ 1.5o – 2.5o • ~constant column density in visible galactic longitude • →gaussian-distributed line source of neutrinos from the galactic disk, isotropic in galactic longitude • sensitivity optimized by an appropriate choice of the on-source region width (i.e. galactic latitude width) • optimal region width is 4.4o (contains >90% of signal) • 90% of selected events in energy range 130GeV < E < 30 TeV • preliminary sensitivity significantly above predictions

25. use space-time localization of the events. Two approaches underway: • Waxman-Bahcall average spectrum hypothesis • νμ search using 312 BATSE bursts (1997-2000) & 139 BATSE+IPN bursts (2000-2003) • preliminary upper limits (of νμ) at Earth: • 1997-2000 ΦνE2 < 4 × 10-8 GeV cm-2 s-1 sr-1 • 2000-2003 ΦνE2 < 3 × 10-8 GeV cm-2 s-1 sr-1 • ongoing all-flavor search using 74 BATSE bursts (2000) • ongoing cascade-like time rolling search with no external trigger (2001) • burst-specific prompt spectrum hypothesis • ongoingνμ search using 200 BATSE bursts (1997-2000) • GRB030329 n telescope : Gamma Ray Bursts

26. rc velocity distribution c Sun ninteractions Earth sscatt nint. mint. nm Gcapture Gannihilation m Detector interactions hadronization Silk, Olive and Srednicki, ’85Gaisser, Steigman & Tilav, ’86 Freese, ’86; Krauss, Srednicki & Wilczek, ’86 Gaisser, Steigman & Tilav, ’86 Indirect WIMP detection

27. Indirect WIMP detection PRELIMINARY Limits on muon flux from Earth center Limits on muon flux from Sun Disfavored by direct search (CDMS II)

28. AMANDA-II AMANDA-B10 detection radius IceCube 30 kpc n from Supernovæ SNEWS is a collaborative effort between Super-K, SNO, LVD, KamLAND, AMANDA, BooNE and several gravitational wave experiments Bursts of low-energy (MeV) neutrinos from core collapse supernovae AMANDA detection: - simultaneous increase of all PMT count rates (~10 s) - can detect 90% of SN within 9.4 kpc - less than 15 fakes per year AMANDA-B10 sees 70% of the galaxy AMANDA-II sees 90% of the galaxy IceCube will see out to the LMC

29. IceCube: the future • first IceCube string deployed (60 Digital OM) • first 4 IceTop Stations deployed (8 tanks/16 Digital OM) DOM being deployed in the ice DOM in the tank ice

30. An IceCube-IceTop event

31. An AMANDA-IceCube event • verification of newly deployed string • off-line synchronization of AMANDA and IceCube data

32. IceCube deployment plan • January 05: • Strings: 1 • Tanks/stations: 8/4 • 05/06 Plan*: • Strings: 10 - 12 • Tanks/stations: 24/12 runway

33. Neutrino flavor nt Full flavor ID supernovae ne ne Showers vs tracks nm 9 12 18 21 6 15 Log(ENERGY/eV) Neutrino flavor identification AMANDA flavor ID Tau Neutrinos: • Regeneration: earth quasi-transparent to nt • Enhanced m & cascade flux due to secondary nm, ne IceCube flavor ID, direction, energy IceCube triggered, partial reconstruction

34. IceCube flavor neutrino detection μ  μ Eµ = 10 TeV E = 375 TeV e  e τ  τ + “cascade” ~300m for 10 PeV t

35. IceCube high energy extension Simulated 2×1019 eV neutrino event in IceCube in AMANDA

36. Summary • No Extraterrestrial neutrino signal observed yet ! • AMANDA-II upper limits getting tighter and constraining models • higher event statistics • good ice properties understanding • improving background rejection capabilities • still improving reconstruction event quality • toward clean atmospheric νμmeasurement as background • improve strategies for sensitivity enhancement • IceCube/IceTop in verification phase (engineering data and preliminary tests) • IceCube/IceTop will significantly improve astrophysics and cosmic rays measurements in energy range and resolution • IceCube will be a powerful all-flavor neutrino detector (particle physics) • IceTop will open the CR measurements up to ~ EeV with high resolution • use of PMT waveforms is a new tool we are learning to use • AMANDA will overlap the lower energy tail of IceCube sensitivity

37. thank you “The n“ @ South Pole

38. Eµ=6 PeV, 1000 hits Eµ=10 TeV, 90 hits IceCube : simulated m track events back