IceCube non-detection of GRB Neutrinos: Constraints on the fireball properties Xiang-Yu Wang Nanjing University, China Collaborators ： H. N. He, R. Y. Liu, S. Nagataki, K. Murase, Z.G. Dai Liverpool GRB meeting June 20, 2012

High-energy neutrino- a new window MeV neutrinos: detected Solar & SN1987A neutrinos Stellar physics (Sun’s core, SNe core collapse) High-energy (>TeV) neutrinos  Study “Cosmic accelerators” 1) 2)

High-energy neutrino production in GRBs Necessary conditions: 1. Proton acceleration 2. Large proton energy fraction 3. Enough thick target 1) 2)

GRB Neutrinos He/CO star H envelope Buried shocks No  -ray emission Razzaque, Meszaros & Waxman ‘03 Precursor ’s Internal shocks Prompt  -ray (GRB) Waxman & Bahcall ’97 Murase & Nagataki 07 Burst ’s External shocks Afterglow X,UV,O Waxman & Bahcall ‘00 Afterglow ’s  p PeV EeVTeV

High-energy neutrino production in GRBs Necessary conditions:  Proton acceleration  Proton energy fraction  Enough thick target 1) 2)

Electron acceleration in GRBs An established fact: afterglow synchrotron emission; prompt non-thermal emission extending to GeV X-ray afterglow of GRB970508Prompt spectrum of GRB090926A

Proton acceleration in GRBs: Waxman (1995): Internal shock acceleration Vietri (1995): External shock acceleration acceleration time = available timeAvailable time acceleration time = cooling time

GRB as a source of UHECRs R_L E/Zqv R_L UHECRs Hillas Plot

Debating point: GRBs can provide enough CR flux? [Waxman 95; Bahcall & Waxman 03] require Galactic sources up to ~ eV 1/E 2 source spectrum Uncertainties: 1 ） Local GRB rate R_0 2 ） E CR /E UHECR 3 ） E CR /E γ (E γ =E e ) GRB: E_γ=1E52.5 erg ， R_0=1/Gpc^3/yr UHECR flux GRB flux

Neutrino production in GRBs Necessary conditions:  Proton acceleration  Proton energy fraction: 1. Proton-electron composition :E p /E e = ~10 2. Poynting-flux dominated : very low  Enough thick target  Dense photon field:  Dense medium: E p /E e = E CR /E γ =?

Standard fireball internal shock scenario Waxman & Bahcall 97, 99 Shock radius: and Baryon composition ~1 neutrino/100 GRB ! Normalized with UHECR flux:

Neutrino spectrum assuming Band function From break in photon spectrum From cooling of pions

Neutrino spectrum He/CO star H envelope Buried shocks No  -ray emission Razzaque, Meszaros & Waxman, PRD ‘03 Precursor ’s Internal shocks Prompt  -ray (GRB) Waxman & Bahcall ’97 Murase & Nagataki 07 Burst ’s External shocks Afterglow X,UV,O Waxman & Bahcall ‘00 Afterglow ’s  CR PeV EeV TeV

IceCube--neutrino detector

IceCube non-detection: fireball model in trouble?

IC40+59 results Stacking analysis on 215 GRBs between April 2008 and May 2010 “Model-dependent” limit for prompt emission model. “Model-independent” limit for general neutrino coincidences (no spectrum assumed) with sliding time window ±Δt from burst. One event 30s after GRB A (“Event 1”) most likely background IceCube: Stacked point-source flux below “benchmark” prediction by a factor 3-4.

However, inaccurate calculation by IceCube of the expected flux 1) Normalization (Li 12, Hummer et al. 12, He et al. 12) 2) Approximate the energy of all the photons using the break energy of the photon spectrum IceCube: Correct:

Neutrino flux– recalculation (He et al. 12) ---accounting for the neutrino oscillation and the cooling of the secondary particles ---ratio between the charged pion number and the total pion number ---four final lepton states share the pion energy ---fraction of the proton energy lost into pions 1/4

Comparison – for one burst Analytic: Delta resonance Numerical calculation: consider the full cross section, direct pion, multi- pion production channels Our calculated flux (numerical result) is one order of magnitude lower than IceCube collaboration

Our result for IC40+59 flux For the same 215 GRBs Using the same benchmark parameters as IceCube team Our results: stacked neutrino flux from 215 GRBs is still a factor of ~3 below the IceCube sensitvity Benchmark parameters: t_v= 0.01 s Γ = 10^2.5, Baryon ratio E p /E γ = 10

General dissipation scenario-constrain the radius R >4 ×10^12 cm

Non-benchmark model parameters Neutrino flux very sensitive to Г Using more realistic Г Liang et al Ghirlanda et al. (2012)

Non-benchmark parameters z=2.15z=1 E p /E γ = 10

Constraints on the baryon ratioE p /E γ

One particular scenario GRB as the source of UHE CR neutrons? (Rachen & Mészáros’98) Neutron can escape independent of normalize to UHE CRs (Ahlers et al. 2011) -> a high neutrino flux -> ruled out !

Diffuse GRB neutrinos Many untriggered GRBs may also produce neutrinos IC40 limit: F<

the injection rate of the neutrinos per unit of time per comoving volume baryon ratio <10 for some LFs LF-L: Liang et al LF-W: Wanderman & Piran (2010) LF-G: Guetta & Piran 2007

Conclusions IceCube current limit (40+59) has not challenged the standard baryon fireball shock model, marginally for low Г models Full IceCube 3 yr observations may constrain the standard baryon fireball shock model GRB-UHECR connection not rule out

Understanding it in another way All-sky total flux in Fermi GBM Expected neutrino flux