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Probing for Leptonic Signatures from Gamma-Ray Bursts with Antarctic Neutrino Telescopes

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 michael.stamatikos@icecube.wisc.edu

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Probing for Leptonic Signatures from Gamma-Ray Bursts with Antarctic Neutrino Telescopes

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  1. Probing for Leptonic Signatures from Gamma-Ray Bursts with Antarctic Neutrino Telescopes MICHAEL STAMATIKOS UNIVERSITYOF WISCONSIN, MADISON DEPARTMENTOF PHYSICSmichael.stamatikos@icecube.wisc.edu GAMMA-RAY BURSTS: THE FIRST THREE HOURS PETROS M. NOMIKOS CONFERENCE CENTER, SANTORINI, GREECE AUGUST 30, 2005 AMANDA

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

  3. 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

  4. Neutrinos from Gamma-Ray Bursts (GRBs) Piran, T. Reviews of Modern Physics 76, 1143-1210 (2004). • 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. 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).

  5. 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/srDiffuse 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

  6. 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)

  7. 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) Beamed Emission Isotropic Emission

  8. Magnetic Field Electron Low-Energy Photon -ray Electron -ray Synchrotron Radiation Self-Compton Scattering Prompt -ray emission of GRB is due to non-thermal processes such as electron synchrotron radiation or self-Compton scattering. --- 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 Radio Prompt GRB Emission Afterglow E  1051 – 1054 ergs Optical Afterglow Radio Afterglow Spatial & temporal coincidence with prompt GRB emission R < 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).

  9. Parameterization of Muon Neutrino Spectrum Neutrino spectrum is expected to trace the photon spectrum. Stamatikos, Band, Hooper & Halzen (In preparation) Guetta et al., Astroparticle Physics 20, 429-455 (2004)

  10. Neutrino Flux Test Models for GRB030329 • 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.

  11. 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. Up-going Events, Detected via charged current interactions: Ahrens, J. et al. Phys Rev D 66, 012005 (2002) AMANDA-II (677 Optical Modules) 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)

  12. Cascade Reconstruction Muon Reconstruction

  13. 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.

  14. 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 - 10h - 5m 0 Nominal Extraction: 2h Nominal Off-Time Interval: 110m Systematic dead-time Down-time of detector True Off-time Bkgd Event rate

  15. Localization of GRB Reconstructed Muon Track  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): • Method B: Discovery potential – Model Discovery Potential (MDP) Method  achieved via minimization of the model discovery factor (MDF): 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)

  16. 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

  17. 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

  18. Signal Efficiency & Background Rejection OptimizationMRFMDF 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

  19. Muon neutrino effective area: AMANDA-II: ~ 80 m2 @ ~2 PeV IceCube: ~700 m2 @ ~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 @ ~200 TeV IceCube: ~ 1 km2 @ ~200 TeV MDF Optimized AMANDA-II Areas for dJ2000~22 (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

  20. Summary of Preliminary Results: GRB030329 • 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. • The number of expected events in IceCube (Ns) for model 3 is consistent with Guetta et al, Astropart. Phys. 20, 429-455 (2004). • 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. 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. Comparison with Other Authors

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

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

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