It is quite likely that other particles (in addition to
-rays)
are emitted in these events. Let
*f*_{x} be the ratio of energy
emitted in other particles relative to
-rays. These
particles will appear as a burst accompanying the GRB. The total
fluence of a "typical" GRB observed by BATSE,
*F*_{} is
10^{-7} ergs/cm^{2}, and the fluence of a "strong" burst
is about hundred times larger. Therefore we should expect accompanying
bursts with typical fluences of:

(137) |

where *E*_{x} is the energy of these particles. This burst
will be
spread in time and delayed relative to the GRB if the particles do not
move at the speed of light. Relativistic time delay will be
significant (larger than 10 seconds) if the particles are not massless
and their Lorentz factor is smaller than 10^{8}! similarly a
deflection angle of 10^{-8} will cause a significant time delay.

In addition to the prompt burst we should expect a continuous
background of these particles. With one 10^{51} ergs GRB per
10^{6} years per galaxy we expect
~ 10^{4} events per galaxy in a Hubble
time (provided of course that the event rate is constant in
time). This corresponds to a background flux of

(138) |

For any specific particle that could be produced one should calculate
the ratio *f*_{x} and then compare the expected fluxes with
fluxes from other sources and with the capabilities of current
detectors. One should distinguish between two types of predictions:
(i) Predictions of the generic fireball model which include low energy
cosmic rays
[220],
UCHERs
[294,
295,
296] and high energy
neutrinos
[297]
and (ii) Predictions of
specific models and in particular the NS^{2}M model. These
include low energy neutrinos
[277]
and gravitational waves
[35,
301].