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Detecting Neutrino Transients with IceCube & optical Follow-up Observations
Marek Kowalski
Penn State, October 2007
Content
• Neutrino bursts: Introduction and science motivation
• Filtering neutrino multiplets, expected rates
• Optical follow up with ROTSE III & Co.
Cosmic Rays & GRBs
Extragalactic
Gamma-Ray Bursts:
GRBs~ 3 1051 ergs x 300/yr/Gpc3
~ 1045 ergs/yr/Mpc3
GRBs could provide environment
and energy to explain the highest
energy cosmic rays! [Waxman 95]
Energy density of extragalactic CR:
CR ~ 1045 ergs/yr/Mpc3
Credit: Meszaros & Murase
MeV neutrinos at collapse
TeV neutrinos from inside the star[Meszaros & Waxman, 2001][Razzaque et al. 2003]
PeV neutrinos from internal shock[Waxman & Bahcall 1997][Gupta & Zhang, 2006][Murase & Nagataki 2006]
PeV-EeV neutrinos from flares[Murase & Nagataki 2006]
EeV neutrinos from external shocks [Dermer 2001][Waxman & Bahcall 2000]
GRBs as sources of high-energy neutrinos Fireball model for long GRBs:
Testing the Supernovae-GRB connection
Observation: Rate of GRBs is just ~1% of SNe Ib/c.
Question: Could there be mildly relativistic jets ( of a few) inside many SNe?
GRBs
SNe ?
Neutrinos could provide the answer:
SN @ 10 Mpc: 30 neutrino events in a cube-kilometer detector!Ando & Beacom, PRL (2005);
Razzaque, Meszaros & Waxman, PRL (2005).Simulation: MacFadyen (2000)
Gravitative collaps of a very massive, rotating star (>25 M):
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IceCube
IceCube Neutrino-Trigger
day 0
day 1-10
network of opticaltelescopes
optical SN/GRBdetection
Optical NeutrinoFollow-up
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Neutrino burst trigger
Doublet background rate:
€
Rdoublet ≈ R2 ΔΩ
2πΔt ≈ 5yr -1
250 a dayFor IceCube
2o x 2o
100 seconds
Background rate of 5 per year,but Field-of-View of 2o x 2o needed.
Other trigger scenarios:
1. Combine -flavors: + e
2. Select high-energy events
Search for transient sources:
Supernova (rising lightcurve)
GRB / Supernova identification
Supernova lightcurves
Strizinger et al. (2003)
Search for transient sources:
Supernova (rising lightcurve)
Gamma-Ray Burst (afterglow)
Gamma-Dark Bursts (orphan afterglows)
Time of explosion:
GRB / Supernova identification
F ~ t-1.2
GRB afterglows
Kahn et al., 2006
10 min
utes
100 second
s
Ando & Beacom flux
Double CoincidenceTriple
coincidence
~20th magnitude detection limit (1 m)~0.003 background
Rat
e [a
rbitr
ary
unit]
Distance [Mpc]
Distribution of Supernovae (simulation)
MK, A. Mohr, 2007
Supernova sensitivity
Ando & Beacom PRL2005
Sensitivity can be doubled by optical follow-up!
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Content
• Science motivation and introduction
• Filtering neutrino multiplets, expected rates
• Optical follow up with ROTSE III & Co.
Coincident atmospheric neutrinos
Neutrino-Rate ~ 4700/yr ~ 29,300/yr
Doublet-Rate ~ 0.15/yr ~ 5.23/yr time-window: 100 sspace-window: 12<4°
weak CutsNDir≥5, Sigma<2.5
IC9 CutsNDir≥9, Sigma<2.5
(IC 40, cuts not optimzed so far)
Localizing the source
median, unweighted
median, weighted
1) Average the two tracks in the multiplet
2)Yet better, use parabolola’s event-wise resolution for weighting:
€
⟨N reco⟩=1
σ 12 + σ 2
2
Nreco,1
σ 12
+Nreco,2
σ 22
⎛
⎝ ⎜
⎞
⎠ ⎟
IC 40, weak cuts
Monitoring detector stability
• Detector stability needs to be monitored on short time scales
• Use of standard IceCube verification and monitoring
techniques
• Decicated variables for burst search
• Event Rate for short time window (e.g. 30 s) • Bin events according direction
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Sky Monitor: Rates (on trigger level)
Azimuth
Zen
ith
Azimuth
Zen
ith
Sky Monitor: Deviation
Significance map,
€
χ = (n−n )2
σ n2( )
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Flasher data to illustrate instability
Significance map,
€
χ = (n−n )2
σ n2( )
Azimuth
Zen
ith
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Thanks to Dawn Williams
Off-time window time
Event time
On-time window time
Event time
Off-source/on time: All, but the 3 closest bins
On-source/off-time: Hit bin and 2 closest neighbours
Zenit
hAzimuth
Zenit
h
Azimuth
Catching Deviations
On-time window time
Event time
Off-source/on time: All, but the 3 closest bins
Zenit
hAzimuth
For each event, use the most significant outlier in the two maps to characterize
detector.
Catching Deviations
worst sigma off-source, on-time
Corsika MC
exp. dataflasher
Content
• Science motivation and introduction
• Filtering neutrino multiplets, expected rates
• Optical follow up with ROTSE & Co.
4 x 0.45 mFoV: 2 x 2 rapid follow-up
ROTSE-III
3a, SSO, Australia
3d, TUG, Turkey
3c, H.E.S.S., Namibia
3b, McDonald, TexasQuickTime™ and a
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Primary & secondary optical follow-up Secondary follow-up with
more powerful telescopes
1) Candidates confirmed or excluded with ~100% eff.
2) Spectroscopy for ID
ROTSE, first generation (2008)
Primary follow-up
Large FoV
Conclusion
• Using neutrino events to trigger optical follow-up observations.
• Significant sensitivity improvement for SNe, and perhaps GRBs.
• For some cases, it’s the only way to identify the source!
• Robotic telescopes for follow-up observations exist and even more will come online soon.
Constructing the Doublets
31
Θ1trueΘ1reco
Θ2reco
Θ2true
Θ1reco
Θ2reco
Spacially “coincident” neutrinos
Uncorrelated atmospheric neutrinos
Optical NeutrinoFollow-up
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Correlating every neutrino (~105/a)?
Next generation of Wide-Field-Imagers: full sky coverage of the optical sky with 3-7 day cadence.
Offline correlation of every neutrino will be possible!
Mir
ror
Are
a X
Fie
ld o
f V
iew
Analysing a ROTSE image
• Of the 83 objects none shows
variations larger than 1 mag
GRB/SN would be identified as
variable object on time-scales of
minutes to days
• 5052 objects identified• Comapare to USNO2.0 reference star
catalog (match to within pixel)• 83 objects not in the catalog
GRB afterglow, 500 s late
Online Burst Filter and Monitor
Line Fit
Paraboloid Fit
Level1-Preselection
Coincidence Filter
Events
Email AlertEvents
• Reconstruct incoming events with first guess
• Preselection to allow full reconstruction of left-over events
• Filter coincident events
• Check stability using monitoring / verification as well as custom-made tools
Sky Rate Monitor
IceCube Monitor
Verification