Transcript Searches for Neutrinos from Gamma Ray Bursts with AMANDA

Searches for Neutrinos from Gamma Ray Bursts with AMANDA-II and IceCube
Brennan Hughey for the IceCube Collaboration
Abstract: The hadronic fireball model predicts a neutrino flux in the TeV to several PeV range simultaneous with the prompt photon emission of GRBs. The discovery of high energy neutrinos in coincidence with a
gamma ray burst would help confirm the role of GRBs as accelerators of high energy cosmic rays. We summarize the methods employed by the AMANDA experiment in the search for neutrinos from GRBs and
present results from several analyses.
1. Overview
3. Detection Channels
2. GRB Properties
The AMANDA detector
 + p →  → + → + + 
→ e+ + e + + 
Gamma ray bursts (GRBs) are the most
energetic explosions ever observed. They
are predicted to produce high energy
neutrinos, primarily through interactions
between protons and gamma rays.
Neutrinos are expected to arrive at Earth in
coincidence with gamma-ray emission,
although precursor and afterglow spectra
have been predicted as well.
Proton-gamma interactions within relativistic jet
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GRB
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Artist’s conception
(Image copyright NASA)
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Predicted diffuse  upper
bounds from GRBs for several
models are shown on the right:
Precursor Emission [1]
Afterglow Emission [2]
Prompt emission models
(coincident with -ray flux):
Waxman-Bahcall flux [3]
Supranova model [4]
Murase-Nagataki (set A flux) [5]
(b) Cascade Event
(a) Muon Track
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Weak force interactions with nucleons in the ice
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


W+
Z0
u
-
particle shower
u
particle shower
AMANDA-II detector at South Pole
The AMANDA-II detector, in operation since
the year 2000, is situated in the ice deep
below the South Pole station. It is
composed of 677 optical modules on 19
strings. A 10-string version of the detector,
called AMANDA B-10, operated from 19971999. Each optical module contains a
photomultiplier tube which detects the
Cherenkov radiation emitted by the decay
products of weak force interactions
between the neutrino and ice particles.
Optical
Module
Bursts are divided into two
classes based on the
bimodal distribution of their
durations as observed by
the BATSE experiment [6].
It is thought that the
different classes may arise
from different progenitors.
Long Bursts
Short Bursts
There are two primary detection channels in AMANDA,
muon track events (a) and more spherically shaped particle
showers, referred to as cascades (b). Muon neutrino
candidates are separated from the dominant atmospheric
muon background by directionality (the Earth filters out
upgoing muons) while cascade events are distinguished by
their unique shape. Effective areas are smaller for
cascades compared to muons, but cascades can be used
to search for neutrino signals from GRBs anywhere in the
sky rather than just those below the horizon.
Figure obviously not to scale
5. Rolling Search
4. Satellite-Coincident Searches
Neutrino searches have been performed
in coincidence with several satellites:
2 event windows in short
burst search
2 event windows in long
burst search
3 event windows in long
burst search
312 bursts detected by BATSE (aboard the CGRO
satellite) in the years 1997-2000 were examined using
the AMANDA muon channel and 73 bursts from the
year 2000 were examined using the cascade channel.
BATSE ceased operations in March of 2000.
95 bursts detected by the IPN3 network were
examined in addition to the BATSE bursts from the
years 2000-2003. This network of gamma-ray
detectors has included HETE-II, BeppoSax, KonusWind and Ulysses, among other satellites.
Background event rates for each burst are established using off-time
windows lasting an hour before and after the burst. The ten minutes
surrounding the burst itself are kept blinded to allow for future
analyses. No events have been observed in coincidence with any
burst analyzed thus far.
6. Limits
The Swift satellite, launched in November 2004,
provides detailed information on each GRB and is
being used for neutrino-coincidence searches with
both AMANDA and the partially constructed IceCube
array.
A rolling time window search, which looks for a clustering of events
consistent with a neutrino signal from a GRB or other transient
phenomenon, has been conducted using the cascade channel for
the 2001, 2002 and 2003 data sets. This analysis is complementary
to satellite-coincident searches, since it is designed to look for bursts
with weak gamma emission or entirely photon-dark transients.
7. Individually Modeled Spectra
(a)
(b)
Limits relative to a Waxman- Bahcall GRB flux for muon (a) and
all flavor (b) analyses are shown below. All flavor limits assume
e:: flavor ratios are 1:1:1.
(a)  limits
(b) Cascade all flavor limits
e +  + 
(c)
Number
Observed
311
Number
Expected
313±18
1000
1016±32
20
21.6±4.8
The rolling search analysis was conducted using two time
windows, opitmized for short and long burst classes. A total
of 7 quality parameters were used to separate high energy
cascade signal events from the background. Results of the
analysis are consistent with no signal being observed, with
the distribution of windows containing more than one event
matching closely the predicted Poissonian background (see
table).
8. IceCube
The first 9 strings of IceCube were
deployed in the 2004-2005 and 2005-2006
austral summer seasons. IceCube will
eventually be a cubic kilometer in size and
have an effective areas nearly two orders
of magnitude larger than AMANDA.
Within the first few years of operation,
IceCube will be able to either positively
identify a GRB neutrino source or place
limits constraining the current theoretical
models of neutrino emission.
references
Recent analyses are utilizing more sophisticated modeling of each GRB. By using parameters measured by
Swift and other satellites, it is possible to predict unique neutrino spectra for each burst. (a): Spectra for prompt
emission from individual bursts from the short burst class. (b): Predicted prompt neutrino emission for “monster
burst” GRB030329 assuming isotropic emission (black) and beamed emission (blue), compared to the WaxmanBahcall reference spectrum (red). (c): Expected events for the 3 models in AMANDA (solid) and IceCube
(dashed).
[1] S. Razzaque, P. Meszaros and E. Waxman Physical Review D,
68, 083001 2003.
[2] E. Waxman and J. Bahcall, Astrophysics Journal 541, 707-711
2000.
[3] E. Waxman and J. Bahcall, Phys. Rev. Lett. 80, 3690 1997.
[4] S. Razzaque, P. Meszaros and E. Waxman Phys. Rev. Lett. 90,
1103 2003.
[5] K. Murase and S. Nagataki, Physical Review D 73, 063 2002.
[6] W.S. Paciesas et al. Astrophysics Journal, 122, 465 1999.