The Enigma of Cosmic Gamma-Ray Bursts: Distance

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Probing for Leptonic Signatures from Gamma-Ray
Bursts with Antarctic Neutrino Telescopes
MICHAEL STAMATIKOS UNIVERSITY OF WISCONSIN,
MADISON DEPARTMENT OF PHYSICS
michael.stamatikos_at_icecube.wisc.edu GAMMA-RAY
BURSTS THE FIRST THREE HOURS
PETROS M. NOMIKOS CONFERENCE
CENTER, SANTORINI, GREECE AUGUST 30, 2005
AMANDA
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Talk Overview

• I. Introduction Motivation
• II. Neutrino Astronomy AMANDA-II
• III. Results

1. Fireball phenomenology the GRB-neutrino
   connection.
2. GRB030329 a case study.

1. Detection principles
2. Flux models and detector response.
3. Optimization methods.

1. Neutrino flux upper limits for various models.
2. Comparison with other authors.

A. Implications for correlative leptonic-GRB
searches.
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New Cosmic Messengers

• Neutrinos could act as new and unique cosmic
  messengers.
• Neutrinos have very little mass and do not
  interact with matter often.
• Neutrinos also have no magnetic moment and are
  not affected by magnetic fields.
• Neutrinos would directly point back to their
  source, making astronomy possible.
• Require up-going event reconstruction to reject
  down-going atmospheric muon background.

AMANDA
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Neutrinos from Gamma-Ray Bursts (GRBs)

• Neutrino astronomy ? new window on the universe
  (Complements EM Spectrum).
• Fireball Phenomenology Relativistic Hadronic
  Acceleration ? Correlated multi-flavored MeV-EeV
  neutrinos from GRBs.
• TeV-PeV muon neutrinos ? spatial temporal
  coincidence with prompt ?-ray emission ?
  Background free search.

Piran, T. Reviews of Modern Physics 76, 1143-1210
(2004).
Stamatikos, M. et al., AIP Conference Proceedings
727, 146-149 (2004)

• Correlation ? Smoking gun signature of hadronic
  acceleration ? possible acceleration mechanism
  for CRs above ankle.
• Null Detection? Possible constraints on
  progenitor or astrophysical models.

Waxman, E. Physical Review Letters 75, 386-389
(1995).
Hjorth, J. et al. Nature 423, 847-850 (2003).
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Neutrinos from Gamma-Ray Bursts (GRBs)

• Original predictions, assumed GRBs were CR
  accelerators and featured averaged (BATSE) GRB
  parameters ? Diffuse flux prediction.
• AMANDA Flux Upper Limits
• Diffuse Muon Neutrino (??) 4 ? 10 -8
  GeV/cm2/s/sr Diffuse Cascade (?e ??) 9.5 ? 10
  -7 GeV/cm2/s/sr
• Electromagnetic observables of GRBs are
  characterized by distributions which span orders
  of magnitude and differ from burst to burst,
  class to class and are effected by selection
  effects.
• Fluctuations may enhance neutrino production.
• EM variance ? neutrino event rate variance.

Razzaque, Meszaros Waxman Phys. Rev. D. 69
023001 (2004)
Waxman Bahcall, Phys. Rev. D 59 023002
5 orders of magnitude
Few GRBs produce detectable signal
Hardtke, R., Kuehn, K. and Stamatikos M.
Proceedings of the 28th ICRC (2003).
Hughey, B. Taboada, I. Proceedings of the 29th
ICRC (2005).
Halzen Hooper ApJ 527, L93-L96 (1999)
Alverez-Muniz, Halzen
Hooper Phys. Rev. D 62, (2000)
Guetta et al., Astroparticle Physics 20 (2004)
429-455
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GRB030329 Prompt ?-Ray Emission (HETE-II)
On-time Search Window
FREGATE Resolution 80 ms
Resolution 160 ms
30-400 keV Energy Band Pass
(SN2003dh)
Trigger Time
41,834.7 UTCs
T90 Time 22.8 ? 0.5 SIs
T95 T90 End 41,871.01 UTCs
T05 ? T90 Start 13.01 SIs
Vanderspek, R. et al. ApJ 617, 1251-1257 (2004)
Barraud, C. et al. astro-ph/0311630
Scaling energy of 15 keV
Prompt photon energy spectrum fit to Band Function
Band, D.L. et al. ApJ 413, 281-292 (1993)
Sakamoto, T. et al. astro-ph/0409128
Vanderspek, R. et al. GCN Report 2212
Vanderspek, R. et al. ApJ 617, 1251-1257 (2004)
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GRB030329 Multi-Wavelength EM Afterglow
GRB030329/SN2003dh
Trigger Time, Duration (T90), Band Spectral Fit
Radio Calorimetry
Taylor et al., GCN Report 2129
Frail et al, ApJ 619, 994-998 (2005)
Emission
Berger et al., Nature 426, 154-157 (2003)
Spectroscopic (Doppler) Redshift
Absorption
Radio Afterglow ? mas positional localization
Price, P.A. et al., Nature 423, 844-847 (2003)
Bloom, J. et al. GCN Report 2212
Isotropic Luminosity 30-400 keV Band Pass
Luminosity Distance
Spergel et al., ApJS 148, 175-194 (2003)
Isotropic Emission
Beamed Emission
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The Fireball Phenomenology GRB-n Connection
GRB Prompt Emission (Temporal) Light Curve

• Shock variability is a unique finger-print
  reflected in the complexity of the GRB time
  profile.
• Implies compact object.

Counts/sec
Time (seconds)
External Shocks
Multi-wavelength Afterglows Span EM Spectrum
Internal Shocks
?-ray
e- p
Optical
X-ray
Prompt GRB Emission
Radio
Afterglow
E ? 1051 1054 ergs
Optical Afterglow
Radio Afterglow
Spatial temporal coincidence with prompt GRB
emission
R lt 108 cm
R ? 1014 cm T ? 3 x 103 seconds
Spectral Fit Parameters
R ? 1018 cm T ? 3 x 1016 seconds
Ag, a, b, egb, egP
Prompt GRB Photon Energy Spectrum Characterized
by the Band Function
Photomeson interactions involving
relativistically (?? 300) shock-accelerated
protons (Ep ? 1016 eV) and synchrotron gamma-ray
photons (E? ? 250 keV) in the fireball wind yield
high-energy muonic neutrinos (E? ? 1014 1015
eV).
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Parameterization of Muon Neutrino Spectrum
Neutrino spectrum is expected to trace the photon
spectrum.
Guetta et al., Astroparticle Physics 20, 429-455
(2004)
Stamatikos, Band, Hooper Halzen (In preparation)
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Neutrino Flux Test Models for GRB030329
Model Model 1 Model 2 Model 3
Parameter Discrete Isotropic Discrete Jet Average Isotropic
Fluence Fg (ergs/cm2) (1.63 ? 0.014) x 10-4 (1.63 ?0.014) x 10-4 6.00 x 10-6
Peak Flux Fg (ergs/cm2/s) 7 x 10-6 7 x 10-6 2 x 10-6
Redshift z 0.168541 ? 0.000004 0.168541 ? 0.000004 1
Low Spectral Index ? -1.32 ? 0.02 -1.32 ? 0.02 -1
High Spectral Index ? -2.44 ? 0.08 -2.44 ? 0.08 -2
Peak Energy ??p (keV) 70.2 ? 2.3 70.2 ? 2.3 1000
Break Energy ??b (keV) 115.6 ? 9.9 115.6 ? 9.9 1000
Luminosity Lg (ergs/s) (5.24 ? 0.82) x 1050 (1.99 ? 0.31) x 1048 1 x 1052
Bulk Lorentz Boost G 178 70 300
Proton Efficiency fp 0.77 0.12 0.2
Normalization Anm (GeV/cm2/s) 9.86 x 10-4 1.54 x 10-4 8.93 x 10-6
Neutrino Break Energy enb (GeV) 1.404951 x 106 2.19343 x 105 1 x 105
Synchrotron Break Energy epb (GeV) 7.9832941 x 107 3.1543774 x 107 1 x 107

• Order of magnitude variance observed for fluence,
  peak photon energy, luminosity neutrino break
  energy.
• Highlighted parameters are directly observed,
  calculated, or fitted. In some cases estimation
  methods exist.

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Antarctic Muon And Neutrino Detector Array

• Largest operational neutrino telescope.
• Viability of HE neutrino astronomy demonstrated
  via usage of ice at the geographic South Pole as
  a Cherenkov medium.
• Successful calibrated on the signal of
  atmospheric neutrinos.
• Construction of IceCube, AMANDA-II's km-scale
  successor, began last winter, with anticipated
  completion by 2010.
• IceCube's instrumented volume will surpass
  AMANDA-II's by the start of 2006.

Up-going Events, Detected via charged current
interactions
AMANDA-II (677 Optical Modules)
Ahrens, J. et al. Phys Rev D 66, 012005 (2002)
Ahrens, J. et al. Astro Phys 20, 2717-2720 (2004)
IceCube (4800 OMs), km-scale
Paciesas, W. et al. ApJSS 122, 465-495 (1999)
Gehrels, N. et al. ApJ 611, 1005-1020 (2004)
Lichti, G. et al. astro-ph/0407137 (2004)
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Cascade Reconstruction
Muon Reconstruction
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Neutrino Flux Models Model 1 Discrete
Isotropic Model 2 Discrete Jet Model 3 Average
Isotropic

• Detector Response
• Strong dependence on break energy, which is a
  function of EM observables.
• Order of magnitude differences in mean energy and
  number of events in detector.

Stamatikos et al., Proceedings of the 29th ICRC
2005
Number of Events1 in IceCube Ns (Dashed)
Model 1 0.1308 Model 2 0.0691
Model 3 0.0038
Number of Events1 in AMANDA-II ns (Solid)
Model 1 0.0202 Model 2 0.0116
Model 3 0.0008
1On-time search window of 40 s, before event
quality selection.
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Statistical Blindness Unbiased Analysis
10m
Blinded Window
Off-Time Background 55m
Off-Time Background 55m
GRB
Time
Diagnostic Analysis Dead-Time/Down-Time
Corrections Event Rate
Diagnostic Analysis Dead-Time/Down-Time
Corrections Event Rate
Trigger Time or T90 start time (Which ever is
earliest)
20h
10h
5m
- 5m
- 10h
0
Nominal Extraction 2h

Nominal Off-Time Interval 110m
Systematic dead-time
Down-time of detector
True Off-time Bkgd
Event rate
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Event Quality Selection Optimization

• Multiple observables investigated ? single,
  robust criterion emerged - maximum size of the
  search bin radius (Y), i.e. the space angle
  between the reconstructed muon trajectory (??,
  ??) and the positional localization of the GRB
  (?GRB, ?GRB)

Fundamental formula of spherical trigonometry

• Up-going events topologically identified via
  maximum likelihood method.
• Method A Best limit setting potential Model
  Rejection Potential (MRP) Method ? achieved via
  minimization of the model rejection factor (MRF)

Based upon Off-time/On-Source Data
Ahrens, J. et al., Nuclear Instruments Methods
A 524, 169-194 (2004b)
Hill Rawlins Astropart. Phys. 19, 393-402
(2003), Feldman Cousins Phys. Rev. D 57,
3873-3889 (1998)
Hill, Hodges, Hughey Stamatikos (in preparation)
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Off-Time Background 24,972 ? 158 Events in
57,328.04 seconds. Expected background rate
0.436 ? 0.003 Hz Number of AMANDA-II background
events (nb) expected on-time (before event
quality selection)
nb 17.44 ? 0.12
On-Time Signal Number of AMANDA-II signal events
(ns) expected on-time (before event quality
selection) Model 1 0.0202 Model 2 0.0116
Model 3 0.0008 On-Time Seconds Search Window
40s
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Signal Sensitivity as a Function of Search Bin
Radius for Model 1
Selection based upon 5? discovery, i.e. 4 events
within 11.3? during 40 second on-time search
window.
Optimizing for discovery reduces limit setting
potential by 5-8. Optimizing for best limit
increases the minimum discovery flux by 17-26.
MDF Optimization Signal
Retention 77 Background
Rejection 99


?


?
MRF Optimization Signal
Retention 86 Background
Rejection 99
Y 11.3? robust across all models
Global minimum was independent of statistical
power
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Signal Efficiency Background Rejection
Optimization MRF MDF Signal
86 77
Retention () Background
99 99
Rejection ()
Vertical Lines Indicate Selection MRF Dashed
(21.3?), dashed-dot (18.8?), dashed-dot-dot
(18.5?) MDF Dotted (11.3?)
Stamatikos et al., Proceedings of 29th ICRC 2005
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Muon neutrino effective area AMANDA-II 80 m2
_at_ 2 PeV IceCube 700 m2 _at_ 2 PeV
Solid Black IceCube Dashed AMANDA-II Model
1 Dashed AMANDA-II Model 2 Dashed AMANDA-II
Model 3
Muon effective area for energy at closest
approach to the detector AMANDA-II 100,000 m2
_at_ 200 TeV IceCube 1 km2 _at_ 200 TeV
MDF Optimized AMANDA-II Areas for dJ200022?
(IceCube Plots not optimized)
Solid Black IceCube Dashed AMANDA-II Model
1 Dashed AMANDA-II Model 2 Dashed AMANDA-II
Model 3
Stamatikos et al., Proceedings of 29th ICRC 2005
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Summary of Preliminary Results GRB030329
Flux Model Maximum Search Bin Radius (AMANDA-II) Maximum Search Bin Radius (AMANDA-II) Expected Number of Background Events (AMANDA-II) Expected Number of Background Events (AMANDA-II) Expected Number of Background Events (AMANDA-II) Expected Number of Signal Events Expected Number of Signal Events Expected Number of Signal Events Observed Number of Events (AMANDA-II) Observed Number of Events (AMANDA-II) Optimization Method (AMANDA-II) Optimization Method (AMANDA-II) GeV/cm2/s (AMANDA-II) GeV/cm2/s (AMANDA-II)
Flux Model YA (?) YB (?) nb nbA nbB Ns IceCube ns AMANDA-II nsB AMANDA-II nobs nobsB MRF (A) MDF (B) SensitivityB LimitB
1 21.3 11.3 17.44 0.23 0.06 0.1308 0.0202 0.0156 15 0 152 424 0.157 0.150
2 18.8 11.3 17.44 0.17 0.06 0.0691 0.0116 0.0092 15 0 256 716 0.041 0.039
3 18.5 11.3 17.44 0.17 0.06 0.0038 0.0008 0.0006 15 0 3864 10794 0.036 0.035
Primed variables indicate value after selection.
Superscripts indicate AMRF and BMDF
optimization method.
Results consistent with null signal, and do not
constrain the models tested in AMANDA-II.
Comparison with Other Authors

1. The number of expected events in IceCube (Ns) for
   model 1 is consistent with Razzaque, Meszaros
   Waxman Phys. Rev. D. 69 023001 (2004), when
   neutrino oscillations are considered.
2. The number of expected events in IceCube (Ns) for
   model 3 is consistent with Guetta et al,
   Astropart. Phys. 20, 429-455 (2004).
3. The number of expected events in IceCube (Ns) for
   model 3 is consistent with Ahrens et al.,
   Astropart. Phys. 20, 507-532 (2004) when the
   assumptions of Waxman Bahcall, Phys. Rev. D 59,
   023002 (1999) are considered.

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Conclusions Future Outlook

1. Leptonic signatures from GRBs would be a smoking
   gun signal for hadronic acceleration revealing a
   possible acceleration mechanism for high energy
   CRs as well as insight to the microphysics of the
   burst.
2. TeV-PeV neutrinos ? observationally advantageous
   ? background free search.
3. Correlative leptonic observations of discrete
   GRBs should utilize the electromagnetic
   observables associated with each burst.
4. No events observed for GRB030329. Robust event
   quality selection.
5. Detector response variance ? unequivocally
   demonstrates the value of discrete modeling, ?
   context of astrophysical constraints on models
   for null results.
6. New era of sensitivity with Swift and IceCube ?
   more complete EM descriptions of GRBs, e.g.
   redshift, beaming, etc. as well as estimator
   methods.
7. Similar results have been demonstrated in the
   context of a diffuse ensemble of BATSE GRBs
   Becker, Stamatikos, Halzen, Rhode (submitted to
   Astroparticle Physics).
8. Ongoing analysis of discrete subset of BATSE GRBs
   Stamatikos, Band, Hooper Halzen (in
   preparation).
9. See Stamatikos et al. Proceedings of the 29th
   ICRC (2005) for details regarding analysis of
   GRB030329.

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Synergy of Gamma-Ray Neutrino Astronomy may be
on the horizon
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