High-energy Neutrino Astrophysics with IceCube Neutrino Observatory Shigeru Yoshida Department of Physics Chiba University

The IceCube Neutrino Observatory Completed: Dec 2010 Configuration chronology 2006: IC9 2007: IC22 2008: IC40 2009: IC59 2010: IC79 2011: IC86 2004: Project Start 1 string 2011: Project completion 86 strings 8 DeepCore 8 strings – spacing optimized for lower energies 480 optical sensors PMT Digital Optical Module (DOM)

The IceCube Collaboration http://icecube.wisc.edu 36 institutions, ~250 members 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 Barbados University of West Indies Sweden Uppsala Universitet Stockholms Universitet Germany Universität Mainz DESY-Zeuthen Universität Dortmund Universität Wuppertal Humboldt-Universität zu Berlin MPI Heidelberg RWTH Aachen Universität Bonn Ruhr-Universität Bochum UK Oxford University Japan Chiba University Belgium Université Libre de Bruxelles Vrije Universiteit Brussel Universiteit Gent Université de Mons-Hainaut Switzerland EPFL, Lausanne New Zealand University of Canterbury ANTARCTICA Amundsen-Scott Station 3

DOM Digital Optical Module HV Base “Flasher Board” Main Board (DOM-MB) 10” PMT 13” Glass (hemi)sphere

Neutrino Detection Principle Observe the charged secondaries via Cherenkov radiation detected by a 3D array of optical sensors νl l, νl hadronic shower W, Z Need a huge volume (km3) of an optically transparent detector material g m Antarctic ice is the most transparent natural solid known (absorption lengths up 200 m) n

Note: Different dataset IC86 = full IceCube (2011~) IceCube IC79 (2010-2011) IC59 (2009-2010) IC40 (2008-2009) IC22 (2007-2008) IceCube IceCube IceCube IceCube

Point Source Search nm  m base m m m North CR signal + background hypothesis vs background only null hypothesis North CR m North South m Note: It’s ALL SKY survey m

n skymap IceCube + IceCube IceCube Preliminary Hottest spot: RA 75.45 Dec -18.15 -log(p)=4.65 ~36 % probability with trial factors up-going m’s w/ atmospheric n BG down-going PeV m’s w/ cosmic-rays BG

GRB Search nm  m base T0: From a satellite GCN Zenith > 85 deg. Off-time On-time Off-time Precursor (~100 s) GRB n modeling – individual GRB bases Prompt Guetta et al Astropart.Phys. 20 (2004) 429 Model Independent (24 h) Background (full year)

No association of n’s with GRB.. Model-dependent limits IceCube IceCube + IceCube We are on the way to indicate GRBs are unlikely to be a major UHECR origin.

Searches for a Diffuse Neutrino Flux 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 Search for excess of astrophysical neutrinos with a harder spectrum than background atmospheric neutrinos Atmospheric ,  Harder Spectrum  (E-2) Astro.  Energy Advantage over point source search: can detect weaker fluxes Disadvantages: high background must simulate background precisely Sensitive to all three neutrino flavors in principle Atm.  Atm.  11

Diffuse n limit nm  m base Now below the Waxman-Bahcall limit 30 TeV ~ 10 PeV Now below the Waxman-Bahcall limit nm only Waxman-Bahcall bound (theoretical reference estimated from cosmic rays flux assuming optically thin sources) IceCube IC40 PRD 84 082001 (2011)

Diffuse n limit All flavor base By looking for cascade events 30 TeV ~ 10 PeV By looking for cascade events IceCube IceCube (expected) PRD 84 072001 (2011)

GZK n search Detection Principle nm nt ne nm nt Energy Dist. @ IceCube Depth Zenith Dist. @ IceCube Depth through-going track And tracks arrive horizontally Secondary m and t from n nm nt  Sensitive to starting track/ cascade Yoshida et al PRD 69 103004 (2004) Directly induced events from n ne nm nt  Sensitive to

GZK n search Detection Principle Experimental verification The detailed description available in PRD 82 072003 (2010) GZK n search Detection Principle Energy  NPE (total # of photoelectrons) Look for luminous (high NPE) horizontal events Experimental verification Data MC overestimates NPE by ~18% MC Sys. error ~ 7% in SIG rate ~ 50% in BG rate

GZK n search All flavor limits IceCube IceCube IceCube PRD 83 092003 (2011) All flavor (ne + nm + nt) limits Systematic errors included IceCube IceCube IceCube (expected) The world’s best all-flavor  upper limits to date from 106 to 1010 GeV

Expected EHE signal events PRD 83 092003 (2011) Models The half IceCube # of events The full IceCube (3 years) 　GZK1 (Yoshida et al) * 0.57 3.1 　GZK2 Strong Evol. (Sigl) ** 0.91 (C.L 53.4%) 4.9 　GZK3 (ESS with WL=0.0) *** 0.29 1.5 　GZK4 (ESS with WL=0.7) *** 0.47 2.5 　GZK5 (Ahlers max) **** 0.89 (C.L 52.8%) 4.8 　GZK6 (Ahlers best fit) **** 0.43 2.3 　Z-Burst # 1.03 (C.L 55.7%) 5.1 　Top Down(SUSY) ## 5.68 (C.L 99.6%) 31.6 　Top Down(QCD) ### 1.19 (C.L 66.4%) 6.3 　W&B(evol) ^ 3.7 24.5 　W&B(no evol) ^ 1.1 5.5 IceCube Here is the expected event rate for various models, with the half IceCube configuration and the full IceCube configuration. It can be seen that by the 2012/5 we can expect a few GZK neutrinos. *Yoshida et al The ApJ 479 547-559 (1997), **Kalahsev et al , Phys.Rev.Rev. D 66 063004 (2002), ***Engel et al, Phys. Rev. D, 64(9):093010, 2001, ****Ahlers et al, Astropart. Phys. 34 106-115 (2010) #Yoshida et al, Phys.Rev.Lett. 81 5505 (1998),##Sigl et al , Phys.Rev.Rev. D 59 043504 (1998), ^Razzaque et al(2003)

p-value for the background hypothesis ~0.2% The Highest NPE event IceCube Keep Cut This event p-value for the background hypothesis ~0.2% (posteriori) Detected in 2008 December 8th NPE 2.55x105 photo-electrons Zenith 64.7 deg Aya Ishihara (Chiba)

Diffuse n limits – global picture As of 2011 reported All “IceCube” is “a half IceCube” with 2008-9 configuration RICE ANITA Auger IceCube HiRes ANTARES 2010 IceCube EHE PRD 83 092003 (2011) IceCube UHE PRD 84 082001 (2011) IceCube VHE 1TeV 1PeV 1EeV 1ZeV

nN CC cross section bound with the IceCube 2008 observation Flux of cosmic n (“Beam Intensity”) Cooper-Sarkar & Sarkar JHEP01:075 (2010) snNSM calculated by Standard Model predictions S.Yoshida PRD 82 103012 (2010)

Fluxes at the IceCube depth Black Hole evaporation scenario J.Alvarez-Muniz et al PRD 65, 103002 (2002) x=1 SM S.Yoshida PRD 82 103012 (2010)

Number of events in the IceCube 2008 run Black Hole evaporation scenario Excluded 90 % C.L. (2.44 events) Cosmic n intensity @ 1 EeV Expected S.Yoshida PRD 82 103012 (2010)

MSSM Neutralino Dark Matter c North CR m n m Spin Dependent cross-section: Abundant hydrogen in Sun suitable for spin dependent cross-section measures Spin Independent cross-section: Many direct dark matter searches sensitive

Dark matter searches: Solar WIMPs Determine the muon flux from the direction of the Sun A few to 103 events per year GeV to TeV energies Limit the neutrino-induced muons from WIMP annihilation A strong limit on SD cross-section and good potential IceCube IceCube Phys. Rev. Lett. 102 201302 arXiv:0902.2460 IceCube Preliminary

Dark Matter from the Galactic Halo Dark matter density profile Dark matter model IceCube IC22 (275 days) found no excess PRD 84 022004 (2011) Measure or limit