IceCube non-detection of GRBs:
Constraints on the fireball composition
and implications for UHECRs
Haoning He
Nanjing University, China
Coauthors: Ruoyu Liu, Xiangyu Wang, ShigehiroNagataki, Kohta Murase, Zigao Dai

Outline• The detection of GRB neutrinos byIceCube• Our modifications for the calculation ofneutrino spectrum• Our results• Conclusions

86 strings in total

Now the 1 year data during theoperation of a full construction,i.e., 86 strings, of IceCube isunder analysis.

GRB neutrinos
Assumptions:Protons and electrons
are accelerated in GRBfireball.
GRB is the major
source of UHECRs.
Waxman & Bahcall 1997

kappes’ talk in kyoto, 2010

IceCube Data Analysis
GRBs Sky Map (2008.04.05-2010.05.30 during the operationsof IceCube 40-string and 59-string configuration)

http://grbweb.icecube.wisconsin.edu

Kappes’ talk in kyoto, 2010

No events are detected for Ic40 and Ic59 data analysis.

Expected neutrino spectrum for IC40 and IC59 detection
by IceCube Collaborator

The IceCube collaboration 2011 a, b

IceCube group suggeststhat the assumption ofGRBs as the major
source of UHECR canbe excluded at a highconfidence.

One of the mistakes of IceCube’s calculation
GRB prompt spectrum

photon density is a function of energy.
The fraction of energy that proton converted
into pions is a function of energy.

However, the IceCube collaborator treats the fraction of energy that proton converted into
pions as the constant at the peak energy when doing the normalization of neutrino flux.
The IceCube collaborator overestimates the flux of neutrinos by a factor of 4-5 than Guetta
et al. 2004.
Li 2011, Hummer et al. 2011, Murase et al. 2011,He,Liu,Wang,Nagataki +,2011, in prep.

The neutrino spectrum for 215 GRBs during theoperations of Ic40 and Ic59 configurations

IceCube collaborator
n_exp=7.89
Guetta et al. 2004
n_exp=2.2
Waxman & Bahcall 1997
n_exp=0.33
Our numerical calculation
n_exp=0.34
Our analytical calculation
n_exp=0.21

for long GRBs

preliminary
a factor of ~6 lower than the upper limit

Constraints on the fireball model fromthe null result

Constrain the ratio of energy of accelerated protons to that of accelerated electrons
Constrain the acceleration radius, or the Lorentz factor of internal shock and thevariability timescale.

Neutrino spectrum for different acceleration radius

A larger acceleration radius leads to alower flux of neutrinos

preliminary
R=10^12cm
R=10^13cm

We roughly assume all the GRBs have thesame acceleration radius and luminosity.

R=10^14cm
R=10^15cm

The neutrino spectrum adopting different luminosityand Lorentz factor

preliminary

z=2.15 for GRB without
measured redshift

z=1 for GRB without
measured redshiftDiffuse GRB neutrino spectrum

preliminary

Conclusions•Our modified numerical calculation predict GRB neutrinos whose flux
is a factor of ~20 lower than that predicted by IceCube group.

•The uncertainties of GRBs parameters affect the flux and shape of theneutrino spectrum.

•

For the null result of IceCube, we can constrain the GRB model andthe flux of protons.

•

We cannot exclude the proposal that GRBs are the major sources ofUHECRs so far.

•We expect that full IceCube operation in 3 years will become deep
enough to test whether GRBs are the major sources for UHECRs orgive a tight constraints on the GRB model.

Thank you!