Alexander Kappes Extra-Galactic sources workshop Jan. 2009, Heidelberg Gamma ray burst detection with IceCube

Alexander Kappes, extra-Galactic sources workshop, Heidelberg Jan 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 crashes into an atom in the ice and produces a nuclear reaction muon travels kilometers in the ice muon νμνμ nuclear reaction blue (Cherenkov) light emitted optical sensors capture (and map) the light cascade

Alexander Kappes, extra-Galactic sources workshop, Heidelberg Jan Detection channels Muons: track of hits good angular resolution (IceCube 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 Pole new South Pole station IceCube lab Skiway IceCube surface area AMANDA surface area

The AMANDA and IceCube neutrino telescopes IceCube: : 1 string : 8 strings : 13 strings : 18 strings : ≥15 strings AMANDA: strings 677 modules IceTop: Air shower detector 160 ice-tanks in surface array Threshold ~300 TeV 1450 m 2450 m InIce: 80 strings each with 60 modules 17 m between modules 125 m between strings Currently deployed: 55 strings 3300 modules 118 IceTop tanks

Alexander Kappes, extra-Galactic sources workshop, Heidelberg Jan 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 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-moonoff-moon difference

Alexander Kappes, extra-Galactic sources workshop, Heidelberg Jan Neutrino flux predictions precursorpromptafterglow Neutrino from GRBs (all flavors) all SNe→BH GRBs only average fluxes → large burst-to-burst fluctuations Meszaros & Waxman Phys.Rev.Lett. 90: (H progenitors) Waxman & Bahcall 1997 Phys.Rev.Lett. 78:2292 Murase & Nagataki 2005 Phys.Rev.D73: (Baryon loading 100) Razzaque etal 2003 (supranova) Phys.Rev. D68: (all GRBs have SNR shell) Waxman 2002 astro-ph/021135

Alexander Kappes, extra-Galactic sources workshop, Heidelberg Jan 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 T0T0 prompt precursor (~100 s) wide window O (-1 h to +3 h) background time 1 evt 2 evt 1 evt

Alexander Kappes, extra-Galactic sources workshop, Heidelberg Jan Best flux limits from AMANDA (final) Neutrino flux limits from GRBs (all flavors) Cascades sliding window 562 d livetime Muons triggered, 419 bursts Precursor: not all SNe→BH have choked jet Prompt: not all GRBs have precursor SN sensitivity reaches Waxman/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 IceCube 22-strings: neutrino flux calculations June April 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 Unbinned likelihood method Input: 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 IceCube: perspectives for stacked analyses Planned 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 ( 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 March 19, 06:12:49 UT (duration ~70 s) Position: RA = 217.9°, Dec = +36.3° Brightest (optical) GRB ever observed: z = 0.94 (D A = 1.6 Gpc) Large number of observations in γ-ray, X-ray and optical ➞ calculation of individual neutrino spectrum (fireball model) GRB B: the “naked-eye” GRB Γ = 500 average WB GRB Γ = 1400 Neutrino spectrum GRB B Γ = 300

Alexander Kappes, extra-Galactic sources workshop, Heidelberg Jan GRB B: 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 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 Toy MC 3 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 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 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 sensitivity with optical coincidence ~30 random doublets per year

Alexander Kappes, extra-Galactic sources workshop, Heidelberg Jan Expected sensitivities (Ando & Beacom model): Optical follow-up active since several weeks (ROTSE) Optical follow-up

Alexander Kappes, extra-Galactic sources workshop, Heidelberg Jan 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 B  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 observations Otherwise exclude Waxman-Bahcall by factor ~10