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

Neutrino Astronomy

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

Amundsen-Scott South Pole station

South PoleDome

Summer camp

AMANDA

road to work

1500 m

2000 m

[not to scale]

O(km) long muon tracks

~15 m

7.0)TeV/(7.0 E

South Pole ice:

Longer absorption length larger effective volume

cascades

event reconstruction byCherenkov light timing

Neutrino Detection in Polar Ice

AMANDA test beam(s):

atmospheric (and ): •Neural Net Energy Reconstruction

(upgoing )

•“Unfold” to get neutrino Energy Spectrum

E2 (E) < 2.6·10–7 GeV cm-2 s-1 sr-1 Limit on diffuse E-2 flux (100-300 TeV):

Atmospheric Neutrinos

PRELIMINARY

Muon Neutrino Flux

Maximum E-2

contribution

Nobs = 1 event

Natm = 0.90

Natm = 0.06 ± 25%norm

+0.69-0.43+0.09-0.04

After optimized cuts:

Diffuse Extra-terrestrial Neutrino Search“Cascade” search: 4 coverage

Signal

Background

Astroparticle Physics 22, 127 (2004)

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

tracks

Simulated UHE event

Nobserved = 5

Nbackground = 4.6 1.2

Astroparticle Physics 22, 339 (2005)

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

Neutrino Point Source Search• Four Year (2000-2003) analysis

– Optimize cuts in each declination band assuming E-2 spectrum– 3369 upgoing events

• < 5% fake events

“Hot spot” searchSignificance Map: Largest excess is 3.35

Assess statistical significance using random skymaps.

No statistically significant hot spots !

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

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.

IceCube Sensitivity

IceCube StatusJanuary 2005: First String Deployed!

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

IceCube Simulated EventsEµ=10 TeV

e e E = 375 TeV

~300m for PeV

"cascade"

How large is IceCube?

50 m

1500 m

2500 m

300

m

AMANDAII

Super K