2,975 research outputs found
TeV neutrinos from core collapse supernovae and hypernovae
A fraction of core collapse supernovae of type Ib/c are associated with
Gamma-ray bursts, which are thought to produce highly relativistic jets.
Recently, it has been hypothesized that a larger fraction of core collapse
supernovae produce slower jets, which may contribute to the disruption and
ejection of the supernova envelope, and explain the unusually energetic
hypernovae. We explore the TeV neutrino signatures expected from such slower
jets, and calculate the expected detection rates with upcoming Gigaton
Cherenkov experiments. We conclude that individual jetted SNe may be detectable
from nearby galaxies.Comment: 4 pages 2 figures. Modified from the published version. Errors in
Eqs. 2, 3, 5 are corrected and predicted neutrino event rates are modified
accordingly. The conclusions for the diffuse flux remain unchanged, and those
for individual nearby sources are strengthene
Mediation: Part I: Background and Overview
Conflict and how we solve it is not new to individuals and countries
The Gradient Expansion for the Free-Energy of a Clean Superconductor
We describe a novel method for obtaining the gradient expansion for the free
energy of a clean BCS superconductor. We present explicit results up to fourth
order in the gradients of the order parameter.Comment: 33 pages, Late
Stability of an Ultra-Relativistic Blast Wave in an External Medium with a Steep Power-Law Density Profile
We examine the stability of self-similar solutions for an accelerating
relativistic blast wave which is generated by a point explosion in an external
medium with a steep radial density profile of a power-law index > 4.134. These
accelerating solutions apply, for example, to the breakout of a gamma-ray burst
outflow from the boundary of a massive star, as assumed in the popular
collapsar model. We show that short wavelength perturbations may grow but only
by a modest factor <~ 10.Comment: 12 pages, 3 figures, submitted to Physical Review
TeV Neutrinos from Successful and Choked Gamma-Ray Bursts
Core collapse of massive stars resulting in a relativistic fireball jet which
breaks through the stellar envelope is a widely discussed scenario for
gamma-ray burst production. For very extended or slow rotating stars, the
fireball may be unable to break through the envelope. Both penetrating and
choked jets will produce, by photo-meson interactions of accelerated protons, a
burst of neutrinos with energies in excess of 5 TeV while propagating in the
envelope. The predicted flux, from both penetrating and chocked fireballs,
should be easily detectable by planned cubic kilometer neutrino telescopes.Comment: Phys.Rev.Letters, in press, final version accepted 8/31/01 (orig.
3/17/01
Kosovo and the Great Air Power Debate
The following section provides an overview of how to think about air power and coercion, addressing several key limits of the current literature. We next examine NATO goals in Kosovo and the mixed success eventually achieved. Using that baseline, we explore various explanations for Belgrade\u27s eventual capitulation and clarify how air power\u27s role in each of them should be understood; we leave aside the issue of whether coercion was a proper strategy for addressing the Balkan crisis and focus instead on how to assess air power as a tool of that strategy. We conclude with recommendations for recasting the air power debate to better reflect air power\u27s true contributions and limits
On the energy of gamma-ray bursts
We show that gamma-ray burst (GRB) afterglow observations strongly suggest,
within the fireball model framework, that radiating electrons are shock
accelerated to a power-law energy distribution, with universal index p \approx
2.2, and that the fraction of shock energy carried by electrons, \xi_e, is
universal and close to equipartition, \xi_e ~ 1/3. For universal p and \xi_e, a
single measurement of the X-ray afterglow flux on the time scale of a day
provides a robust estimate of the fireball energy per unit solid angle,
\epsilon, averaged over a conical section of the fireball of opening angle
\theta ~ 0.1.
Applying our analysis to BeppoSAX afterglow data we find that: (i) Fireball
energies are in the range of 4\pi\epsilon=10^{51.5} to 10^{53.5} erg; (ii) The
ratio of observed -ray to total fireball energy per unit solid angle,
\epsilon_\gamma / \epsilon, is of order unity, satisfying
abs[log10(\epsilon_\gamma/\epsilon)]<0.5; (iii) If fireballs are jet like,
their opening angle should satisfy \theta>=0.1.
Our results imply that if typical opening angles are \theta ~ 0.1, a value
consistent with our analysis, the total energy associated with a GRB event is
in the range of 10^{50} erg to 10^{51.5} erg.Comment: 16 pages; Submitted to Ap
Temperature dependence of the nitrogen-vacancy magnetic resonance in diamond
The temperature dependence of the magnetic resonance spectra of
nitrogen-vacancy (NV-) ensembles in the range of 280-330 K was studied. Four
samples prepared under different conditions were studied with NV-
concentrations ranging from 10 ppb to 15 ppm. For all of these samples, the
axial zero-field splitting (ZFS) parameter, D, was found to vary significantly
with temperature, T, as dD/dT = -74.2(7) kHz/K. The transverse ZFS parameter,
E, was non-zero (between 4 and 11 MHz) in all samples, and exhibited a
temperature dependence of dE/(EdT) = -1.4(3) x 10^(-4) K^(-1). The results
might be accounted for by considering local thermal expansion. The observation
of the temperature dependence of the ZFS parameters presents a significant
challenge for room-temperature diamond magnetometers and may ultimately limit
their bandwidth and sensitivity.Comment: 5 pages, 2 figures, 1 tabl
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