# Presentation: 858109

## 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***
**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**

## Slide 2

## Talk Overview

_**Talk Overview**_

-   I. _**Introduction & Motivation**_**:**** **
-  II. _**Neutrino Astronomy & AMANDA-II**_**:**
- III. _**Results**_**:**
- IV. _**Conclusions & Future Outlook**_**:**

- Fireball phenomenology & the GRB-neutrino connection.
- GRB030329: a case study.

- 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.

## New Cosmic Messengers

_**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**

## 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.
- 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). ***

## 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)***

***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).***

## GRB030329: Prompt -Ray Emission (HETE-II)

***(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*

## 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)***

## The Fireball Phenomenology: GRB- Connection

_**The Fireball Phenomenology: GRB-**__****__** Connection**_

***e******-******    p******+***

** ****E ******** 10****51**** – 10****54**** ergs**

**Internal Shocks**

**Prompt GRB Emission**

**External Shocks**

** ****Afterglow**

** ****Radio**

**Optical**

** ****X-ray**

******-ray**

**Optical Afterglow**

**Radio 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**

## 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)***

## Neutrino Flux Test Models for GRB030329

| Model | Model 1 | Model 2 | Model 3 |
| --- | --- | --- | --- |
| Parameter | Discrete Isotropic | Discrete Jet | Average Isotropic |
| Fluence [F (ergs/cm2) | (1.63  0.014) x 10-4 | (1.63 0.014) x 10-4 | 6.00 x 10-6 |
| Peak Flux [] (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 [L] (ergs/s) | (5.24  0.82) x 1050 | (1.99  0.31) x 1048 | 1 x 1052 |
| Bulk Lorentz Boost [] | 178 | 70 | 300 |
| Proton Efficiency [f] | 0.77 | 0.12 | 0.2 |
| Normalization [A] (GeV/cm2/s) | 9.86 x 10-4 | 1.54 x 10-4 | 8.93 x 10-6 |
| Neutrino Break Energy [b] (GeV) | 1.404951 x 106 | 2.19343 x 105 | 1 x 105 |
| Synchrotron Break Energy [b] (GeV) | 7.9832941 x 107 | 3.1543774 x 107 | 1 x 107 |

_**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. *

## Antarctic Muon And Neutrino Detector Array

- AMANDA-II (677 Optical Modules)

- IceCube            (~4800 OMs), km-scale

*Up-going Events, Detected via charged current interactions:*

_**A**__**ntarctic **__**M**__**uon **__**A**__**nd **__**N**__**eutrino **__**D**__**etector **__**A**__**rray**_

- 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)***

**Notes:**
AMANDA is the Antarctic Muon and Neutrino Detector Array. It is a 3-dimensional array of OMs deployed in the ice shelf that covers the earth’s geographic South Pole.  OMs are optical modules, devices that turn light into electrical signals.  It’s the reverse of a light bulb.  The OMs are attached to long cables lowered in holes that have melted 2 km deep in the ice.  The cables send signals back up to the surface where the data acquisition system “a few computer” records the detections.  This picture shows the scale of the array.  This is the size of the Eiffel Tower compared to AMANDA.  The top of this picture is the surface we walk on, and just below this depth lies the bedrock of the Antarctic continent.  

## Slide 13

## Muon Reconstruction

**Muon Reconstruction**

**Cascade Reconstruction**

## 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.**
**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***

## Statistical Blindness & Unbiased Analysis

_**Statistical Blindness & Unbiased Analysis**_

- Trigger Time or T90 start time *(Which ever is earliest)*

- Time

- + 5m

- - 5m

- 10m

***“******Blinded” Window***

- - 10h

- +10h

- 20h

- Off-Time Background ~55m

- Off-Time Background ~55m

*Diagnostic Analysis*
*Dead-Time/Down-Time Corrections*
* **Event Rate*

*Diagnostic Analysis*
*Dead-Time/Down-Time Corrections*
* **Event Rate*

- GRB

-  0

- Nominal Extraction: 2h                                                                                                 Nominal Off-Time Interval: 110m

- Systematic dead-time                            Down-time of detector

- True Off-time                            Bkgd Event rate

## Event Quality Selection: Optimization

- 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) :

- 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):

***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)***

## Off-Time Background

_**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):*

_**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 = 40**s*

- nb = 17.44  0.12

##                                                                                                                  

**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.**

## Signal Efficiency & Background Rejection

_**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)

## Muon neutrino effective area:

_**Muon neutrino effective area**_:
- _AMANDA-II_:  ~ 80 m2 @     ~2 PeV
- _IceCube_:    ~700 m2 @    ~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 m2 @ ~200 TeV
- _IceCube_:
- ~ 1 km2 @    ~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)***

## 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/cm2/s 
(AMANDA-II) |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
|  | A () | B () | 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 |

_**Comparison with Other Authors**_

- 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.***

## Conclusions & Future Outlook

_**Conclusions & Future Outlook**_

- 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.
- 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.

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

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

**2004**

**Since 1997**

**2005 - 2010**

**2007**