Imaging the Neutrino Universe with AMANDA and IceCube
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Imaging the Neutrino Universe with AMANDA and IceCube
David Hardtke
University of California, Berkeley
1. Motivations for neutrino astronomy
2. Selected AMANDA results
3. IceCube: Status and Plans
Lake Louise Winter Institute February 2005
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Neutrino Astronomy
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Neutrino Production and Detection• Candidate astrophysical
accelerators for high energy cosmic rays:– Active Galactic Nuclei– Gamma-Ray Bursts
• Neutrino production at source: p+ or p+p collisions
• Neutrino astronomy requires large detectors– Low extra-terrestrial
neutrino fluxes– Small cross-sections
dN/dEE-2
dN/dEE-3.7
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Amundsen-Scott South Pole station
South PoleDome
Summer camp
AMANDA
road to work
1500 m
2000 m
[not to scale]
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O(km) long muon tracks
~15 m
7.0)TeV/(7.0 −⋅°≈Θ νμν E
South Pole ice:
Longer absorption length larger effective volume
cascades
event reconstruction byCherenkov light timing
Neutrino Detection in Polar Ice
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AMANDA test beam(s):
atmospheric ν (and μ): •Neural Net Energy Reconstruction
(upgoing μ)
•“Unfold” to get neutrino Energy Spectrum
E2ν (E) < 2.6·10–7 GeV cm-2 s-1 sr-1 Limit on diffuse E-2 νμflux (100-300 TeV):
Atmospheric Neutrinos
PRELIMINARY
Muon Neutrino Flux
Maximum E-2
contribution
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Nobs = 1 event
Natm μ = 0.90
Natm ν = 0.06 ± 25%norm
+0.69-0.43+0.09-0.04
After optimized cuts:
Diffuse Extra-terrestrial Neutrino Search“Cascade” search: 4 coverage
Astroparticle Physics 22, 127 (2004)
Signal
Background
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Diffuse PeV-EeV neutrino search• Earth opaque to PeV
neutrinos look horizontally
• Look for superbright events (large number of Optical Modules with hits)
• Train neural network on dN/dE E-2 signal
μ tracks
Simulated UHE event
Nobserved = 5
Nbackground = 4.6 1.2
Astroparticle Physics 22, 339 (2005)
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Summary of Diffuse Flux Limits
CascadesUnfolded Atmospheric (x3)Horizontal UHE
All-flavor Flux Limits vs. Model Predictions
Models Excluded:
S91 (Stecker et al) AGN Core
S96 (Stecker et al) AGN Core (updated)
P97 (Protheroe) AGN Jet
Barely Alive:
M 95 (Mannheim) AGN Jet
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Neutrino Point Source Search• Four Year (2000-2003) analysis
– Optimize cuts in each declination band assuming E-2 spectrum– 3329 upgoing νμ events
• < 5% fake events
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“Hot spot” searchSignificance Map: Largest excess is 3.35
Assess statistical significance using random skymaps.
No statistically significant hot spots !
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Round Up the Usual Suspects• Search for high energy neutrino excess from
known gamma emitting sources:Usual
suspectz Luminosity
distanceNobserved Nback
1ES 1959+650
0.047 219 Mpc 5 3.71
Markarian 421
0.03 140 Mpc 6 5.58
QSO 1633+382
1.8 14000 Mpc 4 5.58
QSO 0219+428
0.44 2600 Mpc 4 4.31
CRAB 1.9 kpc 10 5.36
TeV Blazars
GeV Blazars
Supernova Remnant
No Statistically Significant Excess from 33 Targeted Objects
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IceCube• 80 strings with 60 optical
modules (OMs) on each• Effective Volume ≈ 1 km3
– Size required to see “guaranteed” neutrino sources
• Surface Array (IceTop)• PMT signal digitization in
ice.
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IceCube Sensitivity
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IceCube StatusJanuary 2005: First String Deployed!
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Conclusions• No Extra-terrestrial neutrino signal observed
– Diffuse flux searches (TeV - EeV)– Point source searches
• No statistically significant hotspots
• No evidence for high-energy neutrino emission from gamma emitting objects
• IceCube under construction– 2-3 order of magnitude improvement in sensitivity
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IceCube Simulated EventsEµ=10 TeV
νe e E = 375 TeV
~300m for PeV ν
€
ν → +"cascade"
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How large is IceCube?
50 m
1500 m
2500 m
300
m
AMANDAII
Super K