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 meetingJune 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 starH envelope

Buried shocksNo -ray emission

Razzaque, Meszaros & Waxman ‘03

Precursor ’s

Internal shocksPrompt -ray (GRB)

Waxman & Bahcall ’97Murase & Nagataki 07

Burst ’s

External shocksAfterglow 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 GRB970508 Prompt spectrum of GRB090926A

Proton acceleration in GRBs:

Waxman (1995): Internal shock acceleration

Vietri (1995): External shock acceleration

acceleration time = available time

eV1020

Available time

acceleration time = cooling time

GRB as a source of UHECRs

R_L<=R B*R>E/Zqv

R_LUHECRsUHECRs

Hillas Plot

Debating point: GRBs can provide enough CR flux?

[Waxman 95; Bahcall & Waxman 03]

yrerg/Mpc10~Const./ 35.432 ppp dnd

• require Galactic sources up to ~1018.5eV

• 1/E2 source spectrum

Uncertainties:

1 ） Local GRB rate R_0

2 ） ECR/EUHECR

3 ） ECR/Eγ (Eγ =Ee)

GRB: E_γ=1E52.5 erg ， R_0=1/Gpc^3/yr

yrerg/Mpc10yr Gpc/1erg10/ 35.43-135.522 dnd

UHECR flux

GRB flux

Neutrino production in GRBs Necessary conditions: Proton acceleration Proton energy fraction:1. Proton-electron composition :Ep/Ee= ~10

2. Poynting-flux dominated : very low

Enough thick target Dense photon field:

Dense medium:

p

pp

Ep/Ee= ECR/Eγ =?

Standard fireball internal shock scenario

2GeV3.0//

;

p

eenp

eV10,eV1010,MeV1 5.14165.2 p

Waxman & Bahcall 97, 99

Shock radius: and Baryon compositiontcR 22

~1 neutrino/100 GRB !

Normalized with UHECR flux:

Neutrino spectrum assuming Band function

From break in photon spectrum

From cooling of pions

22GeV3.0 p

Neutrino spectrum

He/CO starH envelope

Buried shocksNo -ray emission

Razzaque, Meszaros & Waxman, PRD ‘03

Precursor ’s

Internal shocksPrompt -ray (GRB)

Waxman & Bahcall ’97Murase & Nagataki 07

Burst ’s

External shocksAfterglow X,UV,O

Waxman & Bahcall ‘00

Afterglow ’s

CR

PeV

EeV

TeV

22GeV3.0 p

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 091026A (“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 Ep/Eγ = 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. 2010 Ghirlanda et al. (2012)

Non-benchmark parameters

z=2.15 z=1

Ep/Eγ = 10

Constraints on the baryon ratioEp/Eγ

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 !

e-epn

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. 2007LF-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

1-1-2-9

-1-23

sr yr cm GeV106

yr cm erg104

F

1-1-2-9

1-1-2-9

maxp,maxp,

22

sr yr cm GeV108.0

sr yr cm GeV106)/Eln(E

/

8

1

8

1

p

pp

p

ppp

f

EEf

d

dnf

d

dn