Structures in the gamma-ray spectrum

1

• Structures in the gamma-ray spectrum
• Z-bursts
• Topological defects
• TeV Blazars

2

• Topological defects
• Decay of TDs can give rise to UHE cosmic rays
• Models for the decay of TD favour gamma-ray
  dominance
• Gamma-rays from TD decay propagate and can
  accumulate at GLAST energies.
• Depends on the properties of the IR background
  and on the intergalactic magnetic field
• S. Lee, PRD 58(1998)043004

3
CMB
Radio
IR
Lee PRD 58(1998)043004
4
Lee PRD 58(1998)043004
5
Lee PRD 58(1998)043004
6
Ringwald
7

• GEV EMISSION FROM TEV BLAZARS AND INTERGALACTIC
  MAGNETIC FIELDS
• . G Z. Dai, B. Zhang, L. J. Gou, P. Meszaros and
  E. Waxman
• astro-ph/0209091

8

• GeV gamma-rays from TeV gamma-ray emitters
• The TeV gamma-rays interact with the IR
  background and produce electron-positron pairs
• Inverse Compton scattering of the IR photons on
  these electrons/positrons give rise to GeV
  photons
• Flux depends on source activity and the
  intergalactic magnetic field
• Z.G. Dai et al., astro-ph/0209091

9
Dai et al., astro-ph/0209091
10
Dai et al., astro-ph/0209091
11

• Z-bursts
• Proposed to explain airshowers above 5?1019 eV
• Needs flux of neutrinos above 1021 eV
• Needs a neutrino mass in the range 0.1 - 10 eV
• Needs clustering of relic neutrinos

12

• Z-bursts
• Speculative idea
• Payoff can be big!
• (Weiler 1999, Fargion, Mele and Salis 1999)

13
GZK cutoff
AGASA data on cosmic ray spectrum (from Päs and
Weiler, PRD 63(2001)113005)
14
Fargion, Mele, Salis astro-ph/9710029
15
Production of a Z-burst
Nucleons and photons are produced in the Z-decay
with energies that may be above the GZK cutoff.
Photons have a wide energy range.
E?(cosmic) 4(eV/m? ) ZeV
Päs and Weiler PR D63(2001)113015
16
Neutrino mass constraints assuming m3 gt m2 gt m1.
The curved line limits from solar and atmospheric
data. Päs and Weiler Phys Rev D63(2001)113015
17
Momentum distribution in hadronic Z-decays Fodor
et al. hep-ph/0203198
18
GLAST
Structure in spectrum from collisions on the IR
background. Higher energy photons accumulate here
Spectra of nucleons, photons and neutrinos.
Neutrino mass 1 eV. Ringwald ICRC 2001,
hep-ph/0111112
19
Z-burst best fit for different cosmological
evolution parameter ?. Fodor et al. hep-ph/0203198