254 research outputs found
Meson Synchrotron Emission from Central Engines of Gamma-Ray Bursts with Strong Magnetic Fields
Gamma-ray bursts (GRBs) are presumed to be powered by still unknown central
engines for the timescales in the range a few s. We propose that the
GRB central engines would be a viable site for strong meson synchrotron
emission if they were the compact astrophysical objects such as neutron stars
or rotating black holes with extremely strong magnetic fields and if protons or heavy nuclei were accelerated to ultra-relativistic
energies of order . We show that the charged scalar
mesons like and heavy vector mesons like , which have several
decay modes onto , could be emitted with high intensity a thousand
times larger than photons through strong couplings to ultra-relativistic
nucleons. These meson synchrotron emission processes eventually produce a burst
of very high-energy cosmic neutrinos with . These
neutrinos are to be detected during the early time duration of short GRBs.Comment: 12 pages, 4 figures. Accepted for publication in the Astrophysical
Journal Letter
The cyclo-synchrotron process and particle heating through the absorption of photons
We propose a new approximation for the cyclo-synchrotron emissivity of a
single electron. In the second part of this work, we discuss a simple
application for our approximation, and investigate the heating of electrons
through the self-absorption process. Finally, we investigate the self-absorbed
part of the spectrum produced by a power-law population of electrons. In
comparison to earlier approximations, our formula provides a few significant
advantages. Integration of the emissivity over the whole frequency range,
starting from the proper minimal emitting frequency, gives the correct cooling
rate for any energy particle. Further, the spectrum of the emission is well
approximated over the whole frequency range, even for relatively low particle
energies (beta << 0.1), where most of the power is emitted in the first
harmonic. In order to test our continuous approximation, we compare it with a
recently derived approximation of the first ten harmonics. Finally, our formula
connects relatively smooth to the synchrotron emission at beta=0.9. We show
that the self-absorption is a very efficient heating mechanism for low energy
particles, independent of the shape of the particle distribution responsible
for the self-absorbed synchrotron emission. We find that the energy gains for
low energy particles are always higher than energy losses by cyclo-synchrotron
emission. We show also that the spectral index of the self-absorbed part of the
spectrum at very low frequencies differs significantly from the well known
standard relation I(nu) ~ nu^(5/2).Comment: 9 pages, 4 figures, accepted for publication in A&
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