1. Neutrino Astronomy at the South Pole Searches for astrophysical high-energy neutrinos with IceCube Kurt Woschnagg UC Berkeley Miami 2012 Lago Mar, Ft Lauderdale, December 18, 2012

2. p + p → π + … → ν + … or, if E p > 6×10 19 eV, p + γ CMB → Δ → π + n → ν + … Neutrinos and the Origin of Cosmic Rays Cosmic ray spectrum Galactic: SN remnants Extragalactic: AGNs / GRBs / Other We expect high-energy neutrinos from the same sources: ankle 1 particle/(km 2 yr) knee 1 particle/(m 2 yr) 1 particle/(m 2 s) Greisen, Zatsepin, and Kuzmin (1966) GZK cutoff Hillas 2006, arXiv:astro-ph/0607109v2

3. Neutrinos as Cosmic Messengers Cherenkov telescope Interstellar molecular clouds

4. Rate = Neutrino flux x Neutrino Effective Area = Neutrino flux x Neutrino Cross Section x (1 - Absorption in Earth) x Size of detector x (Range of muon for  ) S.Klein, F. Halzen, Phys. Today, May 2008 vertical horizontal  Expected GZK neutrino rates in 1 km 3 detector: ~ 1 per year Size matters: need for a km 3 neutrino detector Effective area (m 2 )

5. IceCube footprint Geographical South Pole Drill Camp DeepCore footprint Skiway Counting house Amundsen-Scott Station (US)

6. The IceCube Neutrino Observatory Digital Optical Module (DOM) Configuration chronology 2006: IC9 2007: IC22 2008: IC40 2009: IC59 2010: IC79 2011: IC86 Completed: Dec 2010 DeepCore 8 strings – spacing optimized for lower energies 480 optical sensors PMT Talk by Ty DeYoung

7. Neutrino Detection Principle Observe the charged secondaries via Cherenkov radiation detected by a 3D array of optical sensors   ν, ν hadronic shower W, Z Need a huge volume (km 3 ) of an optically transparent detector material Antarctic ice is the most optically transparent natural solid known (absorption lengths up to 200+ m)

8. Ice to meet you, neutrinos! But: optical properties depend on depth due to variations in dust concentration: Absorption in ice is weakest where the optical module sensitivity peaks:

9. Background Rejection Atm. Atm.  Up-going Down-going Muons: 2800 Hz Neutrinos: 1 per 10 min Need 10 6 background rejection

10. Tracks  pointing resolution ~1 o Cascades  energy resolution 10% in log(E) Composites  starting tracks  tau double bangs  good directional and energy resolution  e-m and hadronic cascades Neutrino Event Signatures This talk Next talk

11. Moon shadow seen with ~14  Systematic pointing error < 0.1 o Verification of PSF for track reco. on-source preliminary In the Shadow of the Moon IC59 Need high statistics and good angular resolution! Cosmic rays blocked by the moon cause point-like deficit in angular distribution of down-going muons in the detector off-source “left” off-source “right”

12. Neutrino Fluxes: expectations cosmogenic (GZK) ν Stecker AGN (Seyfert) Atmospheric Astrophysical

13. Neutrino Fluxes: atmospheric ν μ cosmogenic (GZK) ν Stecker AGN (Seyfert) Phys. Rev. D83 (2011) 012001 Phys. Rev. D84 (2011) 082001

14. Neutrino Fluxes: atmospheric ν e cosmogenic (GZK) ν Stecker AGN (Seyfert) Next talk: Mariola Lesiak-Bzdak Phys. Rev. D83 (2011) 012001 Phys. Rev. D84 (2011) 082001

15. Atm. Atm.  Search for an excess of astrophysical neutrinos from a common direction over a background of atmospheric neutrinos Search for Neutrino Point Sources

16. All-Sky Point Source Search IC40+IC59+IC79 108,317 upgoing events → >100,000 neutrinos 146,018 downgoing events Livetime: 316 days (IC79) 348 days (IC59) + 375 days (IC40) Northern Sky (below the horizon) Data dominated by atmos. ’s E ~ 10’s - 100’s of TeV Southern Sky (above the horizon) Data dominated by atmos.  ’s E > PeV, increasing with angle E -2 neutrino simulation

17. atmospheric atmospheric  significance All-Sky Point Source Search IC40+IC59+IC79 For each event/direction (previous slide), take PSF from reconstruction and background estimate and add up to make this significance map.

18. atmospheric atmospheric  significance All-Sky Point Source Search IC40+IC59+IC79 -log 10 p = 4.707 nSrc best = 23.07  best = 2.35 Highest significance in azimuthally scrambled skymaps (2000 trials) Hottest spot in Northern sky (Ra=34.25, Dec=2.75) Not significant: 57% of trials have significance ≥ hottest spot

19. atmospheric atmospheric  significance All-Sky Point Source Search IC40+IC59+IC79 -log 10 p = 4.707 nSrc best = 23.07  best = 2.35 Hottest spot in Northern sky (Ra=34.25, Dec=2.75) Not significant: 57% of trials have significance ≥ hottest spot Highest significance in azimuthally scrambled skymaps (2000 trials)

20. atmospheric atmospheric  significance All-Sky Point Source Search IC40+IC59+IC79 -log 10 p = 4.047 nSrc best = 20.81  best = 3.75 Hottest spot in Southern sky (Ra=219.25, Dec=-38.75) Not significant: 98% of trials have significance ≥ hottest spot Highest significance in azimuthally scrambled skymaps (2000 trials)

21. atmospheric atmospheric  significance All-Sky Point Source Search IC40+IC59+IC79 Highest significance in azimuthally scrambled skymaps (2000 trials) -log 10 p = 4.047 nSrc best = 20.81  best = 3.75 Hottest spot in Southern sky (Ra=219.25, Dec=-38.75) Not significant: 98% of trials have significance ≥ hottest spot

22. Point Source Limits IC40+IC59 Upper limits on an E -2 neutrino flux from pre-selected list of astrophysical objects (Blazars, SN remnants, etc)

23. Atm. Atm.  Energy Atmospheric,  Harder Spectrum (E -2 ) Astro. Search for excess of astrophysical neutrinos with a harder spectrum than background atmospheric neutrinos Advantage over point source search: can detect weaker fluxes Disadvantages: high background must simulate background precisely Sensitive to all three neutrino flavors Diffuse Flux = effective sum from all (unresolved) extraterrestrial sources (e.g., AGNs) Possibility to observe diffuse signal even if flux from any individual source is too weak for detection as a point source Searches for a Diffuse Neutrino Flux

24. Attempt to distinguish classes of neutrinos in two dimensions: Search for a diffuse muon neutrino flux IC59 Energy Arrival angle Use reconstructed energy loss as energy estimator ~1° resolution (better for higher energies)

25. Search for a diffuse muon neutrino flux IC59 Two-dimensional likelihood fit to final neutrino sample (21,943 events, <0.2% background muons) PDFs for three neutrino classes (from simulations): Astrophysical: E -2 Conventional: Honda et al., Phys. Rev. D, 75, 043006 (2007) Prompt: Enberg et al., Phys. Rev. D, 78, 043005 (2008) Increased sensitivity to E -2 flux by inclusion of CR knee (Gaisser)

26. Search for a diffuse muon neutrino flux IC59 The highest energy event in the final sample: Best-fit results: E -2 norm = (0.027 + 0.059) ×10 -7 E 2 GeV cm -2 s -1 sr -1 Prompt norm = (0 + 1.216) × [Enberg et al. + Gaisser knee]

27. Limits on a diffuse muon neutrino flux IC59 Experimental upper limits on the diffuse flux of muon neutrinos from sources with  ~ E -2 energy spectrum

28. Limits on a prompt muon neutrino flux IC59 Experimental upper limit on the diffuse flux of atmospheric muon neutrinos from charm decays,  ~ E -2.7

29. Neutrinos from Gamma Ray Bursts Fireball model: Internal shocks in GRBs → acceleration for UHECRs Neutrino production in p-γ interactions in fireball

30. Neutrinos from Gamma Ray Bursts IC40+IC59 Nature 84, 351 (2012) 215 GRBs in Northern sky 2 events observed: both trigger IceTop so likely atmospheric muons Neutrino flux limits in tension with fireball model Search for neutrinos from direction of GRB in short time window (<±1 day) around trigger time (=satellite measurement of GRB):

31. Neutrino and Dark Matter Physics with IceCube DeepCore Tyce DeYoung Department of Physics Pennsylvania State University Miami 2012 Fort Lauderdale December 18, 2012 Selected slides from

32. IceCube DeepCore A more densely instrumented region at the bottom center of IceCube Eight special strings plus 12 nearest standard strings High Q.E. PMTs ~5x higher effective photocathode density In the clearest ice, below 2100 m λ atten ≈ 45-50 m IceCube provides an active veto against cosmic ray muon background (around 10 6 times atmospheric neutrino rate) 250 m 350 m Deep Core extra veto cap AMANDA IceCube scattering

33. Tyce DeYoungMiami 2012December 18, 2012 IceCube DeepCore Original IceCube design focused on neutrinos with energies above a few hundred GeV DeepCore provides ~25 MTon volume with lower energy threshold Higher efficiency far outweighs reduced geometrical volume Note: comparison at trigger level – analysis efficiencies not included (typically ~10%) O(10 5 ) atmospheric neutrino triggers per year

34. Sun Silk, Olive and Srednicki, ’85 Gaisser, Steigman & Tilav, ’86 Freese, ’86 Krauss, Srednicki & Wilczek, ’86 Gaisser, Steigman & Tilav, ’86 et alia velocity distribution ν interactions annihilation channels Indirect Detection of Dark Matter Similar accumulation in Galactic and terrestrial gravitational wells, dwarf spheroidals IceCube can also probe dark matter decay models, other types of dark matter  ρρ σ scatt Γ capture Γ annihilation νμνμ μ

35. Expected Neutrino Energy Spectrum All neutrinos from the Sun are low energy for IceCube (few hundred GeV), even for the highest dark matter masses For Galactic and Earth searches, little neutrino energy loss in the source, so higher energy neutrinos possible – lower threshold probes lower m χ 5 TeV χ → W + W – 5 TeV χ → bb ̅

36. Solar WIMP Search Three event selections applied to 2010 data set: high energy, low energy (winter), and low energy (summer ~ downgoing) After selection, use likelihood analysis to constrain magnitude of simulated WIMP signal in sky map simulated signal (e.g., m χ = 1 TeV) data and off-source background expectation angular separation from Sun

37. Preliminary Results Actual limits on SD scattering and annihilation via soft and hard channels, compared to expected limits (A signal would appear as an upward deviation from the yellow band) No evidence for neutrino flux from solar WIMPs

38. Preliminary Results IceCube and other limits on SD χN scattering cross section Blue shaded region shows MSSM model space not in contradiction to CDMS, XENON, and LHC limits Both SD and SI limits on SUSY models included

39. Tyce DeYoungMiami 2012December 18, 2012 Neutrino Oscillations Energy scale of oscillation phenomena is set by neutrino energy and range of baselines For neutrino path length equal to Earth’s diameter: First oscillation maximum around 24 GeV Hierarchy-dependent matter effects below 10 GeV – too low for DeepCore At these energies, DeepCore dominates the IceCube response ν μ disappearance ν τ appearance Mena, Mocioiu & Razzaque, Phys. Rev. D78, 093003 (2008)

40. Tyce DeYoungMiami 2012December 18, 2012 Muon Disappearance As a first step, compare zenith-dependent response of standard IceCube muon analysis (high energy) to a modified version for DeepCore Look for oscillation signature in event rate suppression at low energies Detector systematics reduced by comparing HE and LE rates Based on traditional muon analysis, no new techniques designed for DeepCore – lower efficiency accepted

41. Muon Disappearance Statistically significant angle-dependent suppression at low energy Shaded bands show range of uncorrelated systematic uncertainties; overall normalization uncertainty shown at right

42. Muon Disappearance Oscillation parameter allowed regions extracted from zenith distributions Systematics included Preliminary results in excellent agreement with world average measurements (with large uncertainties) Potential for significant improvement with inclusion of energy estimators, more advanced reconstructions and event selections

43. Summary Era of km 3 neutrino astronomy has begun 100,000+ high-energy neutrinos on the books No astrophysical neutrino sources detected yet No neutrinos seen from GRBs Setting limits on physics of fireball model Continued gains in sensitivity Detector size, data taking, analysis techniques Low energy neutrino physics with DeepCore Atmospheric oscillations Lots of physics to come: cosmic ray spectrum  cosmic ray composition  cosmic ray anisotropies  atmospheric neutrinos (prompt component, oscillations, effects of quantum gravity, sterile neutrinos, … )  neutrino point sources  gamma ray bursts  GZK neutrinos  multimessenger approaches  diffuse fluxes  dark matter  magnetic monopoles  supernova bursts  shadow of the moon  atmospheric physics  glaciology  climatology  new technologies for highest energies (radio, acoustics)

44. Canada University of Alberta US Bartol Research Institute, Delaware Pennsylvania State University University of California - Berkeley University of California - Irvine Clark-Atlanta University University of Maryland University of Wisconsin - Madison University of Wisconsin - River Falls Lawrence Berkeley National Lab. University of Kansas Southern University, Baton Rouge University of Alaska, Anchorage University of Alabama, Tuscaloosa Georgia Tech Ohio State University Sweden Uppsala Universitet Stockholms Universitet UK Oxford University Belgium Université Libre de Bruxelles Vrije Universiteit Brussel Universiteit Gent Université de Mons-Hainaut Switzerland EPFL, Lausanne Université de Genève Germany Universität Mainz DESY-Zeuthen Universität Dortmund Universität Wuppertal Humboldt-Universität zu Berlin MPI Heidelberg RWTH Aachen Universität Bonn Ruhr-Universität Bochum Japan Chiba University New Zealand University of Canterbury ANTARCTICA Amundsen-Scott Station http://icecube.wisc.edu 37 institutions, ~250 members The IceCube Collaboration Australia University of Adelaide