Issue |
Astron. Astrophys. Suppl. Ser.
Volume 142, Number 3, March II 2000
|
|
---|---|---|
Page(s) | 443 - 445 | |
DOI | https://doi.org/10.1051/aas:2000163 | |
Published online | 15 March 2000 |
TeV gamma-ray emission from gamma-ray bursts and ultra high energy cosmic rays*
Theory Division, National Astronomical Observatory, Mitaka, Tokyo 181-8588, Japan e-mail: totani@th.nao.ac.jp
Received:
1
December
1999
Accepted:
3
January
2000
Some recent experiments detecting very high energy (VHE) gamma-rays above
10-20 TeV, independently reported VHE bursts for
some bright gamma-ray bursts (GRBs), although further confirmation is
necessary. If these signals are truly from GRBs,
these GRBs must emit a much larger amount of energy
as VHE gamma-rays than in the ordinary photon energy range
of GRBs (keV-MeV). We show that such extreme phenomena can be reasonably
explained by synchrotron radiation of protons accelerated to
eV. Protons must carry a much larger amount of energy
than electrons, suggesting that energy transfer
from protons into electrons in shocked matter is very inefficient.
The total energy of GRBs becomes as large as
ergs and hence a strong beaming of GRB emission is highly likely.
There may also be TeV emission in afterglow phase from external shocks, and
proton synchrotron in this phase gives a quantitative explanation for
the famous long duration GeV emission from GRB 940217. Most TeV gamma-rays
are absorbed in intergalactic space by interactions with the infrared and
microwave background radiations, and finally form gamma-ray background in GeV
range. This process may explain the extragalactic
background radiation observed in the EGRET range. We also discuss
absorption of TeV gamma-rays in the shocked region of GRBs
by the
process, which may provide
a new channel for energy transfer from protons into electrons (and
positrons). This process should be important for the energetics of GRBs.
Key words: gamma-ray bursts (GRB)
© European Southern Observatory (ESO), 2000