482 research outputs found
Ultra high energy neutrinos from gamma ray bursts
Protons accelerated to high energies in the relativistic shocks that generate
gamma ray bursts photoproduce pions, and then neutrinos in situ. I show that
ultra high energy neutrinos (> 10^19 eV) are produced during the burst and the
afterglow. A larger flux, also from bursts, is generated via photoproduction
off CMBR photons in flight but is not correlated with currently observable
bursts, appearing as a bright background. Adiabatic/synchrotron losses from
protons/pions/muons are negligible. Temporal and directional coincidences with
bursts detected by satellites can separate correlated neutrinos from the
background.Comment: Adiabatic/synchrotron losses from protons/pions/muons shown to be
negligible. Accepted for publication in Phys. Rev. Letters. RevTe
Neutrinos From Individual Gamma-Ray Bursts in the BATSE Catalog
We calculate the neutrino emission from individual gamma-ray bursts observed
by the BATSE detector on the Compton Gamma-Ray Observatory. Neutrinos are
produced by photoproduction of pions when protons interact with photons in the
region where the kinetic energy of the relativistic fireball is dissipated
allowing the acceleration of electrons and protons. We also consider models
where neutrinos are predominantly produced on the radiation surrounding the
newly formed black hole. From the observed redshift and photon flux of each
individual burst, we compute the neutrino flux in a variety of models based on
the assumption that equal kinetic energy is dissipated into electrons and
protons. Where not measured, the redshift is estimated by other methods. Unlike
previous calculations of the universal diffuse neutrino flux produced by all
gamma-ray bursts, the individual fluxes (compiled at
http://www.arcetri.astro.it/~dafne/grb/) can be directly compared with
coincident observations by the AMANDA telescope at the South Pole. Because of
its large statistics, our predictions are likely to be representative for
future observations with larger neutrino telescopes.Comment: 49 pages, 7 figures. Accepted for publication in Astroparticle
Physic
Neutrinos from Gamma-Ray Bursts in Pulsar Wind Bubbles: \sim 10^{16} eV
The supranova model for Gamma-Ray Bursts (GRBs) is becoming increasingly more
popular. In this scenario the GRB occurs weeks to years after a supernova
explosion, and is located inside a pulsar wind bubble (PWB). Protons
accelerated in the internal shocks that emit the GRB may interact with the
external PWB photons producing pions which decay into \sim 10^{16} eV
neutrinos. A km^2 neutrino detector would observe several events per year
correlated with the GRBs.Comment: Accepted for publication in PRL. 4 pages, 3 figures, minor change
PCV86 The Burden of Non-Adherent Prescription Cost Cutting Among Diagnosed Hypertension Patients in Russia
GeV Photons from Ultra High Energy Cosmic Rays accelerated in Gamma Ray Bursts
Gamma-ray bursts are produced by the dissipation of the kinetic energy of a
highly relativistic fireball, via the formation of a collisionless shock. When
this happens, Ultra High Energy Cosmic Rays up to 10^20 eV are produced. I show
in this paper that these particles produce, via synchrotron emission as they
cross the acceleration region, photons up to 300 GeV which carry away a small,
~0.01, but non-negligible fraction of the total burst energy. I show that, when
the shock occurs with the interstellar medium, the optical depth to
photon-photon scattering, which might cause energy degradation of the photons,
is small. The burst thusly produced would be detected at Earth simultaneoulsy
with the parent gamma-ray burst, although its duration may differ significantly
from that of the lower energy photons. The expected fluences, ~10^{-5}-10^{-6}
erg/cm^2 are well within the range of planned detectors. A new explanation for
the exceptional burst GRB 940217 is discussed.Comment: Accepted for publication in The Physical Review Letters. 4 pages,
RevTeX needed, no figure
On particle acceleration around shocks. I
We derive a relativistically covariant (although not manifestly so) equation
for the distribution function of particles accelerated at shocks, which applies
also to extremely relativistic shocks, and arbitrarily anisotropic particle
distributions. The theory is formulated for arbitrary pitch angle scattering,
and reduces to the well--known case for small angle scatterings via a
Fokker--Planck approximation. The boundary conditions for the problem are
completely reformulated introducing a physically motivated Green's function;
the new formulation allows derivation of the particle spectrum both close and
far away from the injection energy in an exact way, while it can be shown to
reduce to a power--law at large particle energies. The particle spectral index
is also recovered in a novel way. Contact is made with the Newtonian treatment.Comment: Accepted for publication in ApJ; minor changes onl
PMH10 Healthcare Access Differences between Public and Private Insurance Coverage Among Patients with Depression in Brazil
PSY94 Impact of Pain Severity on Patient-Reported Outcomes of Individuals With Chronic Lower Back Pain In Japan
- …