Alexander KappesExtra-Galactic sources workshop13.-16. Jan. 2009, Heidelberg

Gamma ray burst detection with IceCube

Alexander Kappes, extra-Galactic sources workshop, Heidelberg Jan. 2009 2

Outline

• Neutrino detection & neutrino telescopes at the South Pole

• Where we stand- Final best flux limits from AMANDA- Current status of IceCube GRB analyses

• Future perspectives with IceCube- Planned analyses - Optical follow up

Principle of neutrino detection

•infrequently, a cosmic neutrino crashesinto an atom in the ice and produces anuclear reaction

•muon travels kilometers in the ice

muon

νμnuclearreaction

•blue (Cherenkov) light emitted•optical sensors capture (and map) the

light

cascade

Alexander Kappes, extra-Galactic sources workshop, Heidelberg Jan. 2009 4

Detection channels

Muons:• track of hits• good angular resolution

(IceCube <1° for E > 1 TeV)• rather poor energy resolution (IceCube factor ~3)

Cascades:• concentric hits• (almost) no direction information• sensitive to all flavors• low background• better energy resolution achievable

IceCube and AMANDA at the South Pole

South Polenew South Pole station

IceCube lab

Skiway

IceCube surface areaAMANDA surface area

The AMANDA and IceCube neutrino telescopes IceCube:

2004-2005: 1 string2005-2006: 8 strings2006-2007: 13 strings2007-2008: 18 strings2008-2009: ≥15 stringsAMANDA:1995-200019 strings677 modules

IceTop:•Air shower detector•160 ice-tanks insurface array•Threshold ~300 TeV

1450 m

2450 m

InIce:•80 strings eachwith 60 modules•17 m between modules•125 m between strings

Currently deployed:55 strings3300 modules118 IceTop tanks

Alexander Kappes, extra-Galactic sources workshop, Heidelberg Jan. 2009 7

Backgrounds: Atmospheric muons & neutrinos• Significantly higher sensitivity for up-going ν• High-purity (atmospheric) up-going

neutrino sample after cuts

Up-going:ν-induced muons

Down-going:atm. muons

Up-going:ν-induced muons

Backgrounds:•Down-going μ•Atmospheric ν

Data-MC comparison (IceCube 22-strings)

Alexander Kappes, extra-Galactic sources workshop, Heidelberg Jan. 2009 8

preliminary

Pointing accuracy: the Moon shadow• Moon shadow observed in first 3 months of IceCube 40-

string data• Validates pointing capabilities:

Angular resolution:- IceCube 22 < 1.5°- IceCube 80 < 1°

on-moon off-moon

difference

Alexander Kappes, extra-Galactic sources workshop, Heidelberg Jan. 2009 9

Neutrino flux predictions

precursor prompt afterglow

Neutrino from GRBs

(all flavors)all

SNe→BH

GRBs

only average fluxes → large burst-to-burst fluctuations

Meszaros & WaxmanPhys.Rev.Lett. 90:241103(H progenitors)

Waxman & Bahcall 1997Phys.Rev.Lett. 78:2292

Murase & Nagataki 2005Phys.Rev.D73:063002(Baryon loading 100)Razzaque etal 2003 (supranova)Phys.Rev. D68:083001(all GRBs have SNR shell)Waxman 2002astro-ph/021135

Alexander Kappes, extra-Galactic sources workshop, Heidelberg Jan. 2009 10

• GCN-satellite triggered searches- profit from known time (+ direction for muons)- low # events per burst expected ➞ burst stacking

• Untriggered “sliding window” searches- possibly large population of “choked “ GRBs not visible in

γ-rays- sliding window (typically 1 and 100 s):

Search methods

On-time (blind)

Off-time

Off-time

T0promptprecursor (~100 s)

wide window O(-1 h to +3 h)

background

time1 evt2 evt

1 evt

Alexander Kappes, extra-Galactic sources workshop, Heidelberg Jan. 2009 11

Best flux limits from AMANDA (final)Neutrino flux limits from

GRBs(all flavors)

Cascadessliding window 562 d livetime

Muonstriggered, 419 bursts

Precursor:•not all SNe→BH have choked jet

Prompt:•not all GRBshave precursor SN•sensitivity reachesWaxman/Bahcall,Murase/Nagataki fluxes

References:Muons: A. Achterberg etal, ApJ 674:357, 2008 Cascades: A. Achterberg etal, ApJ 664:397, 2007

Alexander Kappes, extra-Galactic sources workshop, Heidelberg Jan. 2009 12

IceCube 22-strings: neutrino flux calculations• June 2007 - April 2008 • 41 satellite-triggered northern bursts (mainly Swift)

with usable IceCube data• Calculation of individual burst spectra

(Waxman-Bahcall GRB flux based on BATSE bursts)

Alexander Kappes, extra-Galactic sources workshop, Heidelberg Jan. 2009 13

• Unbinned likelihood methodInput: position+uncertainty,

time and energy estimator• Search windows:

- prompt: γ-ray emission from satellites

- precursor: 100 s before prompt emission

- wide window: -1h to +3h• Expected events (prompt):

- average WB ~0.7- individual spectra ~0.5

• Unblinding of results soon

IceCube 22-strings: muon analyses

Discovery potential for average WB burst

Effective muon neutrino area

Alexander Kappes, extra-Galactic sources workshop, Heidelberg Jan. 2009 14

IceCube: perspectives for stacked analysesPlanned analyses:• Muons: search for neutrinos from southern GRBs

(reduced sensitivity; cross check with ANTARES)• Cascades: triggered

Prospects:• Expect that IceCube 80-strings will be

3-4 times more sensitive than IceCube 22-strings• With Fermi number of observed GRBs will be ~3

times larger (200-300 per year)IceCube will be able to detect Waxman-Bahcall or

similar GRB fluxes within the next years

Alexander Kappes, extra-Galactic sources workshop, Heidelberg Jan. 2009 15

• March 19, 06:12:49 UT (duration ~70 s)• Position: RA = 217.9°, Dec = +36.3°• Brightest (optical) GRB ever observed:

z = 0.94 (DA = 1.6 Gpc)• Large number of observations in γ-ray, X-ray and

optical➞ calculation of individual neutrino spectrum (fireball model)

GRB 080319B: the “naked-eye” GRB

QuickTime™ and aGIF decompressor

are needed to see this picture.

Γ = 500

average WB GRB

Γ = 1400

Neutrino spectrum

GRB 080319BΓ = 300

Alexander Kappes, extra-Galactic sources workshop, Heidelberg Jan. 2009 16

GRB 080319B: IceCube analysis• Detector was running in maintenance mode

(9 out of 22 strings taking data)• Expect 0.1 events for Γ = 300• No neutrino candidate near GRB position after cuts

➞ 90% upper flux limit (publication soon)

Γ = 300 Would expect O(1) event from similar burst in IceCube 80-strings!

Alexander Kappes, extra-Galactic sources workshop, Heidelberg Jan. 2009 17

Model-independent GRB analysis

• Neutrinos might arrive significantly (up to hours?) earlier or later than prompt γ-ray emission

• Energy spectrum might be quite different than expected• Only close spatial correlation with GRB guaranteed

➞ event weight

• Algorithm:- Start with small time window- Sum weights for events in window

➞ p-value - Successively increase time window

➞ take best p-value

(idea Nathan Whitehorn)

Alexander Kappes, extra-Galactic sources workshop, Heidelberg Jan. 2009 18

Toy MC3 signal events

injected

Model-independent GRB analysis

Toy MC studies:• 10 Million AMANDA-like

background events• Several million time windows• Trial factors only 5-10 for

several hour time windows(windows strongly correlated)

• Application to IceCube data planned

Alexander Kappes, extra-Galactic sources workshop, Heidelberg Jan. 2009 19

Optical follow-up• Potentially large fraction of core-collapse SNe has mildly

relativistic jets that don’t emerge (no γ-ray signal)• 30 neutrino events expected in IceCube for SN @ 10 Mpc

(Ando & Beacom, PRL (2005), Razzaque, Meszaros & Waxman, PRL (2005))

• Use IceCube coincidence to trigger optical follow-up- angular window 4°- time window 100 s

• significant increase in sensitivitywith optical coincidence ~30 random doublets per year

Alexander Kappes, extra-Galactic sources workshop, Heidelberg Jan. 2009 20

• Expected sensitivities (Ando & Beacom model):

• Optical follow-up active since several weeks (ROTSE)

Optical follow-up

Alexander Kappes, extra-Galactic sources workshop, Heidelberg Jan. 2009 21

Summary• AMANDA sensitivity already constrains/touches

neutrino flux predictions • IceCube more than half-way completed (completion in

2011)• Current IceCube GRB analyses:

- Upper limit on neutrino flux from GRB 080319B- Analysis of IceCube 22-string data almost finished

(triggered prompt + precursor + wide-window searches)• With growing IceCube detector + Fermi/Swift good chances

to identify first cosmic neutrino(s)- Model dependent + independent searches- Muon + cascade channel- Optical follow-up observationsOtherwise exclude Waxman-Bahcall by factor ~10