1. Probing for Leptonic Signatures from Gamma-Ray Bursts with Antarctic Neutrino Telescopes M ICHAEL S TAMATIKOS U NIVERSITY OF W ISCONSIN, M ADISON D EPARTMENT OF P HYSICS D EPARTMENT OF P HYSICS michael.stamatikos@icecube.wisc.edu G AMMA- R AY B URSTS: T HE F IRST T HREE H OURS P ETROS M. N OMIKOS C ONFERENCE C ENTER, S ANTORINI, G REECE A UGUST 30, 2005 AMANDA AMANDA

3. Talk Overview I. Introduction & Motivation: II. Neutrino Astronomy & AMANDA-II: III. Results: IV. Conclusions & Future Outlook: A.Fireball phenomenology & the GRB-neutrino connection. B.GRB030329: a case study. A.Detection principles B.Flux models and detector response. C.Optimization methods. A.Neutrino flux upper limits for various models. B.Comparison with other authors. A. Implications for correlative leptonic-GRB searches.

4. 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. Caveat: Very difficult detection. AMANDA

5. Neutrinos from Gamma-Ray Bursts (GRBs) new window on the universeNeutrino 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. GRB030329  Watershed (high-profile) HETE-II Transient  Case Study. Waxman, E. Physical Review Letters 75, 386-389 (1995). Hjorth, J. et al. Nature 423, 847-850 (2003).

6. 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/cm 2 /s/sr Diffuse Cascade ( e &  ) ~ 9.5  10 -7 GeV/cm 2 /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) Guetta et al., Astroparticle Physics 20 (2004) 429-455 Few GRBs produce detectable signal 5 orders of magnitude Neutrinos from Gamma-Ray Bursts (GRBs) Waxman & Bahcall, Phys. Rev. D 59 023002 Hardtke, R., Kuehn, K. and Stamatikos M. Proceedings of the 28th ICRC (2003). Halzen & Hooper ApJ 527, L93-L96 (1999) Alverez-Muniz, Halzen & Hooper Phys. Rev. D 62, (2000) Hughey, B. & Taboada, I. Proceedings of the 29th ICRC (2005).

7. (SN2003dh) Trigger Time: 41,834.7 UTC s T 05  T 90 Start: +13.01 SI s T 90 Time: 22.8  0.5 SI s On-time Search Window FREGATE Resolution ~ 80 ms Resolution ~ 160 ms 30-400 keV Energy Band Pass GRB030329: Prompt  -Ray Emission (HETE-II) T 95 ≡ T 90 End: 41,871.01 UTC s Vanderspek, R. et al. ApJ 617, 1251-1257 (2004) Barraud, C. et al. astro-ph/0311630 Band, D.L. et al. ApJ 413, 281-292 (1993) Prompt photon energy spectrum fit to Band Function Sakamoto, T. et al. astro-ph/0409128 Vanderspek, R. et al. GCN Report 2212 Vanderspek, R. et al. ApJ 617, 1251-1257 (2004) Scaling energy of 15 keV

8. GRB030329: Multi-Wavelength EM Afterglow Isotropic Emission Beamed Emission Emission Absorption Price, P.A. et al., Nature 423, 844-847 (2003) Spectroscopic (Doppler) Redshift Bloom, J. et al. GCN Report 2212 Spergel et al., ApJS 148, 175-194 (2003) Isotropic Luminosity [30-400 keV Band Pass] Luminosity Distance Taylor et al., GCN Report 2129 Radio Calorimetry GRB030329/SN2003dh Trigger Time, Duration (T 90 ), Band Spectral Fit Radio Afterglow  mas positional localization Berger et al., Nature 426, 154-157 (2003) Frail et al, ApJ 619, 994-998 (2005)

9. The Fireball Phenomenology: GRB- Connection Self-Compton Scattering Magnetic Field Electron ---  -ray Synchrotron Radiation Electron  -ray Low-Energy Photon Prompt  -ray emission of GRB is due to non-thermal processes such as electron synchrotron radiation or self-Compton scattering. e-p+e-p+e-p+e-p+ E  10 51 – 10 54 ergs Internal Shocks Prompt GRB Emission External Shocks Afterglow Radio Optical X-ray  -ray Optical AfterglowRadio Afterglow Multi-wavelength Afterglows Span EM Spectrum Photomeson interactions involving relativistically (  300) shock-accelerated protons (E p  10 16 eV) and synchrotron gamma-ray photons (E   250 keV) in the fireball wind yield high-energy muonic neutrinos (E  10 14 – 10 15 eV). R < 10 8 cm R  10 14 cm T  3 x 10 3 seconds R  10 18 cm T  3 x 10 16 seconds Counts/sec Time (seconds) Spatial & temporal coincidence with prompt GRB emission Shock variability is a unique “finger-print” reflected in the complexity of the GRB time profile. Implies compact object. GRB Prompt Emission (Temporal) Light Curve Prompt GRB Photon Energy Spectrum – Characterized by the “Band Function” Spectral Fit Parameters A ,   b,   P

10. 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)

11. ModelModel 1Model 2Model 3 ParameterDiscrete IsotropicDiscrete JetAverage Isotropic Fluence [F   (ergs/cm 2 )(1.63  0.014) x 10 -4 6.00 x 10 -6 Peak Flux [   ] (ergs/cm 2 /s) ~7 x 10 -6 2 x 10 -6 Redshift [z] 0.168541  0.000004 1 Low Spectral Index [  ]-1.32  0.02 High Spectral Index [  ]-2.44  0.08 -2 Peak Energy [   p ] (keV)70.2  2.3 1000 Break Energy [   b ] (keV)115.6  9.9 1000 Luminosity [L  ] (ergs/s) (5.24  0.82) x 10 50 (1.99  0.31) x 10 48 1 x 10 52 Bulk Lorentz Boost [  ] 17870300 Proton Efficiency [f  ]0.770.120.2 Normalization [A  ] (GeV/cm 2 /s)9.86 x 10 -4 1.54 x 10 -4 8.93 x 10 -6 Neutrino Break Energy [  b ] (GeV) 1.404951 x 10 6 2.19343 x 10 5 1 x 10 5 Synchrotron Break Energy [   b ] (GeV) 7.9832941 x 10 7 3.1543774 x 10 7 1 x 10 7 Neutrino Flux Test Models for GRB030329 Order of magnitude variance observed for fluence, peak photon energy, luminosity & neutrino break energy.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.Highlighted parameters are directly observed, calculated, or fitted. In some cases estimation methods exist.

12. AMANDA-II (677 Optical Modules) IceCube (~4800 OMs), km-scale Up-going Events, Detected via charged current interactions: 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. Contemporaneous with satellite GRB observatories such as CGRO, IPN3, Swift & GLAST. Ahrens, J. et al. Phys Rev D 66, 012005 (2002) Ahrens, J. et al. Astro Phys 20, 2717-2720 (2004) Gehrels, N. et al. ApJ 611, 1005-1020 (2004) Lichti, G. et al. astro-ph/0407137 (2004) Paciesas, W. et al. ApJSS 122, 465-495 (1999)

14. Muon Reconstruction Cascade Reconstruction

15. Neutrino Flux Models Model 1: Discrete Isotropic Model 2: Discrete Jet Model 3: Average Isotropic Number of Events 1 in IceCube [N s ] (Dashed) Model 1: 0.1308 Model 2: 0.0691 Model 3: 0.0038 Number of Events 1 in AMANDA-II [n s ] (Solid) Model 1: 0.0202 Model 2: 0.0116 Model 3: 0.0008 Detector Response Strong dependence on break energy, which is a function of EM observables.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.Order of magnitude differences in mean energy and number of events in detector. 1 On-time search window of 40 s, before event quality selection. Stamatikos et al., Proceedings of the 29 th ICRC 2005

16. Statistical Blindness & Unbiased Analysis Trigger Time or T 90 start time (Which ever is earliest) Time + 5 m - 5 m 10 m “Blinded” Window - 10 h +10 h 20 h Off-Time Background ~55 m Diagnostic Analysis Dead- Time/Down- Time Corrections Event Rate Diagnostic Analysis Dead- Time/Down- Time Corrections Event Rate 0 Nominal Extraction: 2 h Nominal Off-Time Interval: 110 m Systematic dead-time Down-time of detector True Off-time Bkgd Event rate

17. Event Quality Selection: Optimization single, robust criterion emerged - maximum size of the search bin radius (  ),Multiple observables investigated  single, robust criterion emerged - maximum size of the search bin radius (  ), i.e. the space angle between the reconstructed muon trajectory (  ,   ) and the positional localization of the GRB (  GRB,  GRB ) :  Reconstructed Muon Track Localization of GRB Up-going events topologically identified via maximum likelihood methodUp-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): Method B: Discovery potential – Model Discovery Potential (MDP) Method  achieved via minimization of the model discovery factor (MDF): Fundamental formula of spherical trigonometry Hill & Rawlins Astropart. Phys. 19, 393-402 (2003), Feldman & Cousins Phys. Rev. D 57, 3873-3889 (1998) Hill, Hodges, Hughey & Stamatikos (in preparation) Based upon Off- time/On-Source Data Ahrens, J. et al., Nuclear Instruments & Methods A 524, 169-194 (2004b)

18. 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 (n b ) expected on-time (before event quality selection): On-Time Signal Number of AMANDA-II signal events (n s ) expected on-time (before event quality selection): Model 1 = 0.0202 Model 2 = 0.0116 Model 3 = 0.0008 On-Time Seconds Search Window = 40 s n b = 17.44  0.12

19. Optimizing for discovery reduces limit setting potential by ~5-8%. Optimizing for best limit increases the minimum discovery flux by 17-26%. Global minimum was independent of statistical power  ≤ 11.3  robust across all models Signal Sensitivity as a Function of Search Bin Radius for Model 1 MRF Optimization Signal Retention: ~ 86 % Background Rejection: ~99 % MDF Optimization Signal Retention: ~ 77 % Background Rejection: ~99 %   Selection based upon 5  discovery, i.e. 4 events within 11.3  during 40 second on-time search window.

20. Optimization MRF MDF Signal 86 77 Retention (%) Background 99 99 Rejection (%) Stamatikos et al., Proceedings of 29 th ICRC 2005 Signal Efficiency & Background Rejection Vertical Lines Indicate Selection: MRF – Dashed (21.3  ), dashed-dot (18.8  ), dashed-dot-dot (18.5  ) MDF – Dotted (11.3  )

21. Muon neutrino effective area: AMANDA-II: ~ 80 m 2 @ ~2 PeV IceCube: ~700 m 2 @ ~2 PeV Stamatikos et al., Proceedings of 29 th ICRC 2005 Muon effective area for energy at closest approach to the detector: AMANDA-II: ~100,000 m 2 @ ~200 TeV IceCube: ~ 1 km 2 @ ~200 TeV Solid Black = IceCube Dashed = AMANDA-II Model 1 Dashed = AMANDA-II Model 2 Dashed = AMANDA-II Model 3 Solid Black = IceCube Dashed = AMANDA-II Model 1 Dashed = AMANDA-II Model 2 Dashed = AMANDA-II Model 3 MDF Optimized AMANDA-II Areas for  J2000 ~22  (IceCube Plots not optimized)

22. Summary of Preliminary Results: GRB030329 Flux Model Maximum Search Bin Radius (AMANDA-II) Expected Number of Background Events (AMANDA-II) Expected Number of Signal Events Observed Number of Events (AMANDA-II) Optimization Method (AMANDA-II) GeV/cm 2 /s (AMANDA-II) A()A() B()B() nbnb n b A’ n b B’ N s IceCube n s AMANDA-II n s B’ AMANDA-II n obs n obs B ’ MRF (A) MDF (B) Sensitivity B Limit B 121.311.317.440.230.060.13080.02020.01561501524240.1570.150 218.811.317.440.170.060.06910.01160.00921502567160.0410.039 318.511.317.440.170.060.00380.00080.00061503864107940.0360.035 Comparison with Other Authors Razzaque, Meszaros & Waxman Phys. Rev. D. 69 023001 (2004), 1.The number of expected events in IceCube (N s ) for model 1 is consistent with Razzaque, Meszaros & Waxman Phys. Rev. D. 69 023001 (2004), when neutrino oscillations are considered. Guetta et al, Astropart. Phys. 20, 429-455 (2004). 2.The number of expected events in IceCube (N s ) for model 3 is consistent with Guetta et al, Astropart. Phys. 20, 429-455 (2004). Ahrens et al., Astropart. Phys. 20, 507-532 (2004)Waxman & Bahcall, Phys. Rev. D 59, 023002 (1999) 3.The number of expected events in IceCube (N s ) 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. Primed variables indicate value after selection. Superscripts indicate A=MRF and B=MDF optimization method. Results consistent with null signal, and do not constrain the models tested in AMANDA-II.

23. Conclusions & Future Outlook smoking gun signal for hadronic accelerationpossible acceleration mechanism for high energy CRs 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 neutrinosbackground free search 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 3.Correlative leptonic observations of discrete GRBs should utilize the electromagnetic observables associated with each burst. 4.No events observed for GRB030329 4.No events observed for GRB030329. Robust event quality selection. 5.Detector response variance  unequivocally demonstrates the value of discrete modeling 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 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. [Becker, Stamatikos, Halzen, Rhode (submitted to Astroparticle Physics)]. 7.Similar results have been demonstrated in the context of a diffuse ensemble of BATSE GRBs [Becker, Stamatikos, Halzen, Rhode (submitted to Astroparticle Physics)]. [Stamatikos, Band, Hooper & Halzen (in preparation)]. 8.Ongoing analysis of discrete subset of BATSE GRBs [Stamatikos, Band, Hooper & Halzen (in preparation)]. 9.See Stamatikos et al. Proceedings of the 29 th ICRC (2005) for details regarding analysis of GRB030329 9.See Stamatikos et al. Proceedings of the 29 th ICRC (2005) for details regarding analysis of GRB030329.

24. A MAND A Synergy of Gamma-Ray & Neutrino Astronomy may be on the horizon 2004 Since 1997 2005 - 2010 2007