Results from the AMANDA Neutrino Telescope
CRIS06, Catania, June 2006
Juande D. ZornozaUniversity of Madison-Wisconsin
Neutrino Astronomy
• Photons interact with the CMB and with matter• Cosmic rays are deflected by magnetic fields and also interact with matter• Neutrons are not stable
High energy astronomy: Which probes can we use?
What else? Oh, yeah, neutrinos!
Photon and proton mean free range path
Neutrino CV
•Neutral•Stable•Weakly interacting*
*very large detectors needed
Production Mechanisms Gamma and cosmic ray astrophysics
are deeply related with neutrino astronomy:
YYKXN )(...)(
)()( eee
0 N X Y Y
Neutrino flavor rate: e:: ~ 1:2:<10-5 at the sourcee:: ~ 1:1:1 at the detector
Cosmic rays
Gamma ray astronomy
Scientific Scopes
??
Other physics: monopoles, Lorentz invariance, super-massive DM , SUSY Q-balls, etc...
~MeV
Supernovae
Average increase in the PMT
counting rate
TeV-PeV
Astrophysical sources(AGNs,
GRBs, MQs)
Up-going muons and cascades
PeV-EeV
AGNs, TD, GZK
neutrinos
Almost horizontal
tracks
EeV
?
Down-going tracks
Energy
Physics
Signature
GeV-TeV
Neutralino search
Up-going muons
AMANDA/IceCube Collaboration
USA (12)USA (12)Europe (13)Europe (13)
JapanJapan
New ZealandNew Zealand
• Bartol Research Institute, Delaware, USA• Pennsylvania State University, USA• UC Berkeley, USA• UC Irvine, USA•Clark-Atlanta University, USA• Univ. of Maryland, USA
• Bartol Research Institute, Delaware, USA• Pennsylvania State University, USA• UC Berkeley, USA• UC Irvine, USA•Clark-Atlanta University, USA• Univ. of Maryland, USA
• IAS, Princeton, USA• University of Wisconsin-Madison, USA• University of Wisconsin-River Falls, USA• LBNL, Berkeley, USA• University of Kansas, USA• Southern University and A&M College, Baton Rouge, USA
• IAS, Princeton, USA• University of Wisconsin-Madison, USA• University of Wisconsin-River Falls, USA• LBNL, Berkeley, USA• University of Kansas, USA• Southern University and A&M College, Baton Rouge, USA
• Universite Libre de Bruxelles, Belgium• Vrije Universiteit Brussel, Belgium• Université de Gent, Belgium • Université de Mons-Hainaut, Belgium• Universität Mainz, Germany• DESY-Zeuthen, Germany• Universität Dortmund, Germany
• Universite Libre de Bruxelles, Belgium• Vrije Universiteit Brussel, Belgium• Université de Gent, Belgium • Université de Mons-Hainaut, Belgium• Universität Mainz, Germany• DESY-Zeuthen, Germany• Universität Dortmund, Germany
• Universität Wuppertal, Germany• Uppsala university, Sweden• Stockholm university, Sweden• Imperial College, London, UK• Oxford university, UK• Utrecht,university, Netherlands
• Universität Wuppertal, Germany• Uppsala university, Sweden• Stockholm university, Sweden• Imperial College, London, UK• Oxford university, UK• Utrecht,university, Netherlands
• Chiba university, Japan• University of Canterbury, Christchurch, NZ
• Chiba university, Japan• University of Canterbury, Christchurch, NZ
South Pole
Runway
AMANDA-II
Amundsen-Scott South Pole Station
AMANDA Detector 1997-99: AMANDA-B10 (inner lines of AMANDA-II)
10 strings 302 PMTs
from 2000: AMANDA-II 19 strings 677 OMs 20-40 PMTs / string
At the surface: SPASE
Coincident events Angular resolution Cosmic ray
composition2 km
1 km
SPASE
trigger rate = 80 Hz
SignaturesCC- interactions:long (~km) tracks
NC- and CC-e/ interactions:cascades
7.0)TeV/(7.0 E (tracks short w.r.t. the inter-OM distance)
15 m
• Other signatures, like double bang, are expected to be more rare.
Background•There are two kinds of background:
-Muons produced by cosmic rays in the atmosphere (→ detector deep in the ice and selection of up-going events).-Atmospheric neutrinos (cut in the energy, angular bin…).
ee
Kp
...)(
ee
Kn
...)(
p
p
Ice Properties Shorter scattering length than in sea, but longer
absorption length (larger effective volume):
bubbles
dust
Absorption
dust
ice
Average optical ice parameters:
abs ~ 110 m @ 400 nmsca ~ 20 m @ 400 nm
Scattering
Moreover, very “silent” medium: dark noise < 1.5 kHz
Event reconstruction The position, time and amplitude registered by
the PMTs allows the reconstruction of the track, using Likelihood optimization techniques.
The angular resolution depends on the quality cuts of each specific analysis. For instance, in the point-like source search, it is 2.25-3.75 deg (declination dependent).
Once reconstructed the positions of the tracks, we can compare the number of events in each signal bin with the background at that declination.
example of AMANDA event
signal bin
background estimation
Sky map
The largest fluctuation (3.4) is compatible with atmospheric background
~92%
2000-2003 (807 days)
3329 s detected from Northern Hemisphere
3438 atmospheric s expected
Performance
aver
age
flu
x u
pp
er li
mit
[cm
-2s-1
]
sin
AMANDA-B10
AMANDA-II
Neutrino Effective Area Sensitivity to E-2 Point-like sources
• Sensitivity: Average upper limit, integrated above 10 GeV.• Steady increase with time.
•For E<10 PeV, Aeff grows with energy due to the increase of the interaction cross section and the muon range.•For E>10 PeV the Earth becomes opaque to neutrinos.
Ndet=Aeff × Time × Flux
AGNs: Stacking source analysis
single source sensitivity(four years)
Neutrino astronomy could be the key for establishing the hadronic/leptonic origin of the HE photons from AGNs.
Stacking-source analysis: The flux from AGNs of the same type integrated to enhance the statistics.
prel
imin
ary
No significant excess has been found. The stacking approach improves the one source limit by a factor three, typically.
Multi-wavelength approach Transient events also provide an opportunity to enhance sensitivity We can look for correlations with active periods from electromagnetic
observations: Blazars: X-rays Microquasars: radio
SourcePeriod wtih high activity
#events in high state
Expected background in high state
Markarian 421 141 days 0 1.63
1ES1959+650 283 days 2 1.59
Cygnus X-3 114 days 2 1.37
2000-03 data
sources: TeV blazars, microquasars and variable sources from EGRET
Transient sources When the variable character of the source is evident, but the EM
observations are limited, we can use the sliding-window technique. For the time-rolling source search, events in a sliding time window are
searched: Galactic: 20 days Extragalactic: 40 days
Source #events(4 years)
Expected background(4 years)
Period duration
Markarian 421 6 5.58 40 d
1ES1959+650 5 3.71 40 d
3EG J1227+4302 6 4.37 40 d
QSO 0235+164 6 5.04 40 d
Cygnus X-3 6 5.04 20 d
GRS 1915+105 6 4.76 20 d
GRO J0422+32 5 5.12 20 d
sources: TeV blazars, microquasars and variable sources from EGRET
Gala
cti
cExtr
ag
ala
cti
c
Orphan Flare Three events in 66 days within the
period of a mayor 1ES 1959+650 burst (orphan flare:s but no X-rays)
A posteriori search undefined probability of random coincidence.
sliding search window
Diffuse fluxes
Atmospheric neutrino spectrum is reconstructed using regularization-unfolding techniques.
No extraterrestrial diffuse component has been observed.E2 d/dE = 1.1 x 10-7 GeV cm-2 s-1 sr-1
(over the range 16 TeV to 2 PeV)
UHE neutrinos (I)
UHE neutrinos (>106 GeV) can be produced in several scenarios (AGNs, topological defects, GZK…)
>107 GeV the Earth is opaque to neutrinos search for horizontal tracks.
Background: muon bundles from atmospheric showers.
Neural network trained to distinguish between signal and background
simulated UHE event
UHE neutrinos (II)
Signal versus background: Signal produces higher light density There are more hits in UHE single muons, due to the
after-pulsing in the photomultipliers. Background events are produced mainly vertically down-
wards and signal events are expected to be horizontal. Different residual time distributions (because of after-
pulsing) Center of gravity of hits pulled away from the geometrical
center of the detector for down-going bundles.
UHE neutrinos (III) 2000 data used for this analysis:
20% for the optimization of cuts 80% after unblinding is approved
There is a factor two of improvement in the sensitivity w.r.t. AMANDA B10
Limit = 3.710-7 GeV cm-2 s-1 sr-1
(from 1.8105 to 1.8109 GeV)
UHE neutrinos (IV)
PRELIMINARY sensitivities to different models of UHE production:
Source
Number expected in 80% of 1 year
(138.8 days)all
MRF for 80% sample(FC = 3.49)
AGN core (Stecker et al 96) 37.0 0.09
AGN core (Stecker et al 92) 8.9 0.39
AGN jet (Protheroe 96) 8.9 0.40
AGN jet (Halzen and Zas 97) 8.5 0.41
Z-Burst (Kalashev et al 02) 3.6 0.96
Mono-Energetic p-γ (Semikoz 03) 0.65 5.4
Topological Defect (Sigl et al 98) 0.63 5.5
E-2 p-γ (Semikoz 03) 0.45 7.8
Z-Burst (Yoshida et al 98) 0.15 24.0
p-γ (Engel et al 01) 0.012 298.8
L. Gerhardt
SGR 1806-20
We try to observe down-going muons produced by TeV photons discriminating the background of atmospheric muons using an
angular and a time window
RA (J2000) 18h 08m 39.4s = 272.16 deg
DEC (J2000) -20deg24'39.7" = -20.41 deg
SatelliteTrigger time at Earth
(ms)
GEOTAIL 21:30:26.71
INTEGRAL 21:30:26.88
RHESSI 21:30:26.64
CLUSTER 4 21:30:26.15
Double Star 21:30:26.49
Duration < 0.6 s
Time window 1.5 s0.4 s
The SGR 1806-20 flare (Dec. 2004) was more than The SGR 1806-20 flare (Dec. 2004) was more than one order of magnitude more powerful (2x10one order of magnitude more powerful (2x104646 erg) than previous flares: detectors saturated.erg) than previous flares: detectors saturated.
+
Swift-BAT light curveSwift-BAT light curve
SGR 1806-20
MDF have jumps when we have to increase the (discrete) number of events needed to satisfy the condition of 5 confidence interval.
MRF behaves smoothly since only the mean expected background in taken into account.
5 events, time window: 1.5 s Confidence interval=5Statistical Power=90%
DiscoveryDiscovery Optimum cone size: 5.8°Optimum cone size: 5.8°
Best MDF: 2.3Best MDF: 2.3
Observed events Observed events needed: 4needed: 4
Background: 0.06Background: 0.06
SGR 1806-20
neutrinos
gammas
• Limits in the constant of a d/dE=A E-1.47 flux are set, constraining both the HE gamma and neutrino emission.
preliminary
Effective areas Limit in flux normalization
Unfortunately, no event was found after unblinding, so upper limits have been calculated.
GRBs (average spectrum) Search time window: from 10 sec
before the burst start to the end of the burst.
Precursor: from -110 sec to -10 sec. Background estimation: from 1
hour before to 1 hour after (except 10 minutes around the burst which remain unblinded)
years # GRBs selection criterion limit (GeV cm-2 sr-1)
97-00 312 BATSE 410-8
00-03 139BATSE + IPN
310-8
00-03 (with precursor) 50 510-8
00 74 BATSE 9.510-7
Neutralino Search
WIMPs would scatter elastically in the Sun or Earth and become gravitationally trapped.
They would annihilate producing standard model particles.
Among the annihilation products, only neutrinos can reach us.
Neutralinos annihilate in pair-wise mode:
2
2ann
ann m
v
ann: annihilation rate per unit of volumeann: neutralino-neutralino cross-sectionv: relative speed of the annihilating particles: neutralino mass densitym: neutralino mass
HWHZHHZZWWll , , , , , 02,1
003
02,1
00
and neutrinos are produced as secondaries.
Neutralino Search
excluded by Edelweiss
The Sun is the most promising source of neutralinos.The Sun is the most promising source of neutralinos.Neutralino density in the Earth is diminished the effect of the Neutralino density in the Earth is diminished the effect of the Sun mass.Sun mass.
Conclusions AMANDA has been operating for almost one
decade. No extraterrestrial neutrino has been observed
above the atmospheric background,
Increasingly stringent limits have been set in point-like sources, diffuse fluxes, neutralinos…
A bigger detector is needed IceCube (already in construction!)
but sometimes success comes after much work and patience!
YET…
Thanks to the organizers!
Backup transparencies
Particle Physics
Monopoles Monopoles would also give a large signal in the detector, which can be
discriminated from high energy muons. Two signatures are possible:Direct emission (βm>0.74): ×8500 wrt muonInduced δ-ray emission (βm>0.51)
GRB model parameterization
b
s
'A
FA
ztF
zEss
bb
,,
,
1
1
90
0
GRBs (individual spectrum)
The individual spectrum can be used instead of the average to enhance the sensitivity for a given burst.
The parameters of the Band function of the GRB030329 burst were calculated.
0.0350.036average (WB) (3)
0.0390.041beamed (2)
0.1500.157isotropic (1)
Limit
(GeV s-1 cm-2)
Sensitivity
(GeV s-1 cm-2)
Model
12
3
neutrino energy flux (GeV cm-2 s-1)
GRBs: individual bursts
AGN models Low energy (from radio up to UV / X-
ray): non-coherent synchrotron radiation. High energy (up to TeV) under debate:
leptonic versus hadronic models.