Astronomy with neutrinos: AMANDA and IceCube

Transcription

1 Astronomy with neutrinos: AMANDA and IceCube Albrecht Karle University of Wisconsin-Madison Joint symposium on GeV to TeV astrophysics in the era of GLAST SLAC, Sep 2004 icecube.wisc.edu

2 AMANDA collaboration Bartol Research Inst, Univ of Delaware, USA Univ. of Alabama, USA Pennsylvania State University, USA Clark-Atlanta University, USA University of Wisconsin-Madison, USA Univ. of Maryland, USA University of Wisconsin-River Falls, USA IAS, Princeton, USA LBNL, Berkeley, USA University of Kansas, USA UC Berkeley, USA Southern Univ. and A&M College, Baton Rouge UC Irvine, USA Chiba University, Japan University of Canterbury, Christchurch, New Zealand Universidad Simon Bolivar, Caracas,Venezuela Université Libre de Bruxelles, Belgium Vrije Universiteit Brussel, Belgium Université de Mons-Hainaut, Belgium Universität Mainz, Germany DESY-Zeuthen, Germany Universität Wuppertal, Germany Uppsala Universitet, Sweden Stockholm universitet, Sweden Kalmar Universitet, Sweden Imperial College, London, UK University of Oxford, UK Utrecht University, Utrecht, NL

3 Energy (ev) Flux Radio CMB Visible GeV γ-rays / ν TeV sources! cosmic rays

4 Signals and backgrounds Atmospheric muon flux: downgoing Atmospheric neutrino flux: 4 pi, low energy Astrophysical neutrino fluxes: HE, all flavor Array

5 Amundsen-Scott South Pole Station road to work South Pole Dome AMANDA 1500 m Summer camp 2000 m [not to scale]

6 Deployment of string - AMANDA

7 µ-event Upgoing muon event in AMANDA-II Muons provide good pointing information. Angular resolution: 1.5 to 2.5

8 µ-event Upgoing muon event in AMANDA-II Good sensitivity towards horizon Efficient background rejection of downgoing muons

9 Neutrino effective area Effective areas Muon effective area E.g. at 30 TeV: Muon area: 35,000 m 2 Neutrino area: 1 m 2

10 AMANDA-II ν - Sky: point source search 4 YEARS COMBINED DATA Preliminary

11 ν Sky : point source search Maximum significance 3.4 σ compatible with atmospheric ν Preliminary ν from northern hemisphere 3438 ν expected from atmosphere also search for neutrinos from unresolved sources Search for clustering in northern hemisphere compare significance of local fluctuation to atmospheric ν expectations ~92% un-binned statistical analysis no significant excess

12 Upper limits to point sources average flux upper limit [cm -2 s -1 ] AMANDA-II AMANDA-B10 * Average upper limit = sensitivity (δ>0 ) (integrated above 10 GeV, E -2 signal) (*) optimized for E -2, -3 signal Sensitivity independent of direction 1997 : Ap.J. 583, 1040 (2003) 2000 : PRL 92, (2004) IceCube : Astrop Phys 20, 507 (2004) Preliminary Φν lim cm -2 s -1 sin(δ) δ declination δ=0 o δ=90 o

13 Results (Examples) Object Declination Events observed Events background Neutrino Limit 2000* 4 year Neutrino Limit* Mrk Mrk Crab SS *Assumed E -2 spectrum for 90% c.l. in units: 10-7 E -2 GeVcm -2 s -1

14 Compare neutrino limits and sensitivity to observed gamma fluxes. Example: Mrk 501 (1997) HEGRA 97 (gammas) 4 year limit

15 Search for ν μ correlated with GRBs GRB catalogs: BATSE (non-)triggered, IPN3 & GUSBAD Assumed WB spectrum (E B at 100 TeV and Γ=300) E 2 Φ ν ~ 4 x 10-8 GeVs -1 cm -2 sr -1 PRELIMINARY Year Total Total 00 #GRB 78 BT 94 BT 96 BT 44 BT 312 BT 24 BNT 46 New 114 all BT = BATSE Triggered BNT = BATSE Non-Triggered Low background due to space and time coincidence ΔΨ<20, in 10 min Average effective bkg observed m-area» m / New = IPN & GUSBAD Elisa Bernardini, AMANDA -- Now /

16 Neutrino limits to diffuse fluxes constraint models diffuse (B10) cascades/3 unfolded UHE/3 Upper limits on diffuse ET neutrino fluxes Atmospheric ν energy spectrum, limit Cascades, 1 year Ultra High Energy, 1 yr back

17 IceCube IceTop Skiway AMANDA South Pole 80 Strings 4800 PMT Instrumented volume: 1 km 3 (1 Gt) 1400 m 2400 m

18 ν - flavours and energy ranges Oscillations --> all flavors important ντ νe νe νµ Filled area: particle id, direction, energy Shaded area: energy only Log(energy/eV)

19 10 PMT Hamatsu -70

20 Track reconstruction in low noise environment AMANDA-II 10 TeV Typical event: PMT fired Track length: km Flight time: 4 µsecs Accidental noise pulses: 10 p.e. / 5000 PMT/4µsec 1 km

21 Angular resolution < 0.5 to 1 (med) Resolution 0.8 deg (median) Improves slightly with energy Better near horizon: 0.7 (Sample more strings) Search bin 1.0 Solid angle: 2π/6500

22 Sensitivity of Gamma ray telescopes Sensitivity of IceCube to neutrinos AMANDA (neutrinos) IceCube (neutrinos) log(e/ev) point sources, E^-2 spectrum Plot on left from Steve Ritz Sensitivity (2π sr, 100% ontime): 3 years exposure, 5 sigma E^-2

23 Diffuse fluxes: Energy resolution Small detectors: Muon energy is difficult to measure because of fluctuations in de/dx IceCube: Integration over large sampling+ scattering of light reduces the fluctutions energy loss. E µ =10 TeV, 90 hits E µ =6 PeV, 1000 hits

24 Example: Diffuse Fluxes - Predictions and Limits Macro Baikal Amanda IceCube Sensitivity after 3 years

25 Neutrinos from Gamma Ray Bursts For 1000 GRB observed: Expected signal: 11 upgoing muon events Expected background: 0.05 events (small time window/burst of o(sec)) Essentially background free detection: Only 200 GRB needed to detect standard fireball prediction (Waxman/Bahcall 99)

26 Cascade Energy = 375 TeV event ν e + N --> e- + X νe e E = 375 TeV The length of the actual cascade, 10 m, is small compared to the spacing of sensors ==> roughly spherical density distribution of light, --> timing gives directionality Total energy deposition in medium - fully active calorimeter --> good energy resolution of neutrino energy diameter (>1 pe) ~ 0.5 km

27 τ-neutrino --> Double Bang Learned, Pakvasa, 1995 ντ + N --> τ- + X ντ + X (82%) Regeneration makes Earth quasi transparent for high energie ντ; (Halzen, Salzberg 1998, ) Also enhanced muon flux due to Secondary µ, and ν µ (Beacom et al.., astro/ph ) ~300m for 10 PeV ντ E << 1PeV: Single cascade (2 cascades coincide) E 1PeV: Double bang E >> 1 PeV: partially contained (reconstruct incoming tau track and cascade from decay)

28 Construction

29

30 South Pole Dark sector AMANDA Skiway Dome IceCube

31 Summary/Conclusions Neutrino astronomy has achieved new regions of sensitivity comparable to some observed AGN gamma fluxes GRB sensitivity about one order of magnitude above standard fireball prediction galactic sources other physics: atmospheric neutrinos, dark matter, SN, cosmic rays (composition),... IceCube: factor of 100 improvement in most parameters Construction is under way: First strings in Jan 2005, completion in 2010 Neutrinos astronomy to complement gamma astronomy in the era of GLAST

32 Point sources: event rates Flux equal to 3x current AMANDA limit dn/de = 10-6 *E -2 /(cm 2 sec GeV) Atmospheric Neutrinos AGN* (E -2 ) Sensitivity (E -2 /(cm 2 sec GeV)) All sky/year (after quality cuts) 100,000 - Search bin/year year: Nch > 43 (E > 7 TeV) x 10-9 Compared to AMANDA-II: 7 times more PMT --> 50 to 100 times more atmosph. better angular and energy resolution

33 µ cm -2 s southern sky 4 years Super-Kamiokande northern sky 170 days AMANDA-B years MACRO Expected sensitivity for AMANDA SS-433 Mk-501 ν/γ ~ 1 Measured sensitivity days AMANDA-II declination (degrees)