5 research outputs found
Multi-GeV Neutrinos from Internal Dissipation in GRB Fireballs
Sub-photospheric internal shocks and transverse differences of the bulk
Lorentz factor in relativistic fireball models of GRB lead to neutron diffusion
relative to protons, resulting in inelastic nuclear collisions. This produces
significant fluxes of ~3 GeV muon neutrinos (antineutrinos) and ~2 GeV electron
neutrinos (antineutrinos), scaling with the Lorentz factor eta < 400. This
extends significantly the parameter space for which neutrinos from inelastic
collision are expected, which in the absence of the above effects requires eta
> 400. A model with sideways diffusion of neutrons from a slower wind into a
fast jet can lead to production of muon and electron neutrinos (antineutrinos)
in the 2-25 GeV or higher range, depending on the value of eta. The emission
from either of these mechanisms at z~1 may be detectable in suitably densely
spaced detectors.Comment: 10 pages, aas latex, 1 figure, subm. to ApJ(Lett) 7/6/200
5-10 GeV Neutrinos from Gamma-Ray Burst Fireballs
A gamma-ray burst fireball is likely to contain an admixture of neutrons, in
addition to protons, in essentially all progenitor scenarios. Inelastic
collisions between differentially streaming protons and neutrons in the
fireball produce muon neutrinos (antineutrinos) of ~ 10 GeV as well as electron
neutrinos (antineutrinos) of ~ 5 GeV, which could produce ~ 7 events/year in
kilometer cube detectors, if the neutron abundance is comparable to that of
protons. Photons of ~ 10 GeV from pi-zero decay and ~ 100 MeV electron
antineutrinos from neutron decay are also produced, but will be difficult to
detect. Photons with energies < 1 MeV from shocks following neutron decay
produce a characteristic signal which may be distinguishable from the
proton-related MeV photons.Comment: 4 pages, latex, 1 figure, aps style files. Final version, accepted in
Phys.Rev.Lett., 6/22/2000; some clarifications in the text, same conclusion
High Energy Neutrino Astronomy: Towards Kilometer-Scale Detectors
Of all high-energy particles, only neutrinos can directly convey astronomical
information from the edge of the universe---and from deep inside the most
cataclysmic high-energy processes. Copiously produced in high-energy
collisions, travelling at the velocity of light, and not deflected by magnetic
fields, neutrinos meet the basic requirements for astronomy. Their unique
advantage arises from a fundamental property: they are affected only by the
weakest of nature's forces (but for gravity) and are therefore essentially
unabsorbed as they travel cosmological distances between their origin and us.
Many of the outstanding mysteries of astrophysics may be hidden from our sight
at all wavelengths of the electromagnetic spectrum because of absorption by
matter and radiation between us and the source. For example, the hot dense
regions that form the central engines of stars and galaxies are opaque to
photons. In other cases, such as supernova remnants, gamma ray bursters, and
active galaxies, all of which may involve compact objects or black holes at
their cores, the precise origin of the high-energy photons emerging from their
surface regions is uncertain. Therefore, data obtained through a variety of
observational windows---and especially through direct observations with
neutrinos---may be of cardinal importance. In this talk, the scientific goals
of high energy neutrino astronomy and the technical aspects of water and ice
Cherenkov detectors are examined, and future experimental possibilities,
including a kilometer-square deep ice neutrino telescope, are explored.Comment: 13 pages, Latex, 6 postscript figures, uses aipproc.sty and epsf.sty.
Talk presented at the International Symposium on High Energy Gamma Ray
Astronomy, Heidelberg, June 200
High-energy Neutrino Astronomy: The Cosmic Ray Connection
This is a review of neutrino astronomy anchored to the observational fact
that Nature accelerates protons and photons to energies in excess of
and eV, respectively.
Although the discovery of cosmic rays dates back close to a century, we do
not know how and where they are accelerated. Basic elementary-particle physics
dictates a universal upper limit on their energy of eV, the
so-called Greisen-Kuzmin-Zatsepin cutoff; however, particles in excess of this
energy have been observed by all experiments, adding one more puzzle to the
cosmic ray mystery. Mystery is fertile ground for progress: we will review the
facts as well as the speculations about the sources including gamma ray bursts,
blazars and top-down scenarios.
The important conclusion is that, independently of the specific blueprint of
the source, it takes a kilometer-scale neutrino observatory to detect the
neutrino beam associated with the highest energy cosmic rays and gamma rays. We
also briefly review the ongoing efforts to commission such instrumentation.Comment: 83 pages, 18 figures, submitted to Reports on Progress in Physic