IceCube: Multiwavelength Approach to
Transient Neutrino Point Source Candidates
Elisa Resconi, for the IceCube coll.
(Max-Planck-Institute for Nuclear Physics, Heidelberg)
http://icecube.wisc.edu
TeV Particle Astrophysics II 28-31 August 2006. Madison, WI
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1. Construction of the Neutrino Sample
106 : 1
l
F
(E,
W)
n
n
IceCube event
IceCube
event
Elisa
Resconi
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2. Extraction of Astronomical Information
Fn (E, W) = Fatm + Fgalactic + Fextra- galactic
Cosmic ray showers in
the Earth’s atmosphere:
- p, K decay
 E-3.7
 20% uncertainty
“diffuse” flux:
CR interaction with
interstellar gas.
“diffuse” flux:
p decay from pg interaction
with 2.7oK cosmic radiation
“point-like”:
galactic sources
“point-like”:
extra-galactic
sources
TeV-Blazar
 E-2  ?
discussed here
 E-2  ?
See also at this conference:
“Implications of neutrino flux limits” J. Becker for IceCube, talk
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“Search for a Diffuse Flux of TeV to PeV Muon Neutrinos with AMANDA-II” J. Hodges for IceCube, poster
Fgalactic(E,W), Fextra-galactic(E,W) point-like sources
Ref. M. Ackermann, “The multimessenger approach ..”,
Barcelona, 07.06
On-Source
= 00-04
Off-Source
AMANDA-II preliminary: 2000-2004 (1001 live days),
4282 n from northern hemisphere
NoBlind
significant
analysis
excess
strategy
found
Elisa Resconi
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Multi-wavelength approach: photon light curves used for the improvement in identify
possible neutrinos emitted by astronomical sources
Synthetic light curve
Photon Rate
(counts/sec)
Nr of n
dFatm(t)/dt = 1 / year 3o sky-bin
1 n / day sky-bin ~ 310 -3
1
2000
2001
How can we discriminate
these events ?
2002
2003
Time
What can we learn from
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photon observations?
3. Transient Point Sources
1. The photon-neutrino link
Selection of neutrino “proxy” waveband
2. Access to photon data
Availability / calibration / dead-time correction …..
3. Analysis of photon data
WHAT IS A FLARE ?
Elisa Resconi
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3.1 The photon – neutrino link: HBL (LBL)
Synchrotron proton blazar model (ref. A. Mücke et al, Astroparticle Phy, 18 (2003) 593-613)
proton
pγ
(highly magnetized environment)
p
, n
γ
γ synchr
e, n
γ synchr
casc. (e±)
γ synchr
 e, n
electron
γ synchr.
X
γ
γ synchr.
casc. (e±)
γ synchr
LBL
HBL
P.Giommi et al.,A&A 445, 843-855 (2006)
Elisa Resconi
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X- AND γ-ray
HBL
γ- ray band
X- ray band
Interpretation primary electron AND
secondary electron (casc.)
Data
huge amount of data,
monitor + high sensitivity
Strategy
Light curve interpretation
define “flares”
define periods of high activity
Elisa Resconi
n emission
C
O
R
R
E
L
A
T
I
O
N
only p,
if only synchrotron (no n)
sporadic, no monitor,
difficult to combine
collect all the data available,
improve definition of “flare”
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3.3 Photon data: WHAT IS A FLARE ?
Light Curve Interpretation:
 characteristic flux level(s)
 impulsive events (flares)
 statistical studies on the timescales of variability
 correlated activities across wavebands
 periods of HE neutrino emission:
Construction of an hypothesis test
Maximum Likelihood Blocks applied to X- and g-ray light curves
[E. Resconi, L. Costamante, D. Franco, E. Flaccomio, A. Gross, icecube/200608002]
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X-ray: an example
All-Sky-Monitor (RXTE), Mkn 421
All-Sky-Monitor, RXTE, 10 years X-ray monitor
Elisa Resconi
zoom Mkn 421
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All-Sky-Monitor, Maximum-Likelihood-Blocks
Elisa Resconi
zoom Mkn 421
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All-Sky-Monitor, Maximum-Likelihood-Blocks, Characteristic level
zoom Mkn 421
Rchar
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Hypothesis test: need to be blind!
1. n sample determined a priori
2. Time periods selected a priori
3. n in the time periods / n atmospheric expected
All-Sky-Monitor, Maximum-Likelihood-Blocks, Characteristic level
zoom Mkn 421
Elevated levels or flares : ~ 15 %
+ 3
Rchar
Characteristic level (band)
Depends on: source + detector
Elisa Resconi
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TeV g-ray: preliminary
 The light curves are very sporadic
 Compilation of historical light curves: under construction
Mkn 421, Whipple public data,
Maximum Likelihood Blocks
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g-ray flux
Multi-wavelength: X- vs g-ray
“Orphan” region
Correlated
corridor
“Anti-orphan” region
X-ray flux, PCA (MLB blocks)
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Future:
… transition to a ‘multi-messengers’ approach
- IceCube as a ( half ) – All-Sky-Monitor in neutrino:
- Filed of view: northern sky
- High duty cycle
- Idea: use neutrinos in order to trigger gamma-ray telescopes
(see E. Bernardini, “The multimessenger approach..” Barcelona, 07.06)
- Critical points under discussion:
- selection of the sources: the phenomenology is limited
- statistical interpretation of possible coincidences:
g-ray flare rate, catalogue …
- blindness of the data:
minimal impact with off-line analysis
- Status: TEST run between AMANDA and Magic of 3 months approved.
Elisa Resconi
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Summary
 Looking in the right direction and in the right moment is a good idea!
 From existing models: selection of proxy wavebands (HBL discussed)
 Photon light curves under compilation
 Photon light curve analysis with a global method (MLB)
 Selection of periods of possible neutrino emission:
 global &
 non arbitrary
 Next: test on the data
Elisa Resconi
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