2,615 research outputs found
Abelian Higgs Hair for AdS-Schwarzschild Black Hole
We show that the Abelian Higgs field equations in the background of the four
dimensional AdS-Schwarzschild black hole have a vortex line solution. This
solution, which has axial symmetry, is a generalization of the AdS spacetime
Nielsen-Olesen string. By a numerical study of the field equations, we show
that black hole could support the Abelian Higgs field as its Abelian hair.
Also, we conside the self gravity of the Abelian Higgs field both in the pure
AdS spacetime and AdS-Schwarzschild black hole background and show that the
effect of string as a black hole hair is to induce a deficit angle in the
AdS-Schwarzschild black hole.Comment: 19 pages, 33 figure
HESS J1616-508: likely powered by PSR J1617-5055
HESS J1616-508 is one of the brightest emitters in the TeV sky. Recent
observations with the IBIS/ISGRI telescope on board the INTEGRAL spacecraft
have revealed that a young, nearby and energetic pulsar, PSR J1617-5055, is a
powerful emitter of soft gamma-rays in the 20-100 keV domain. In this paper we
present an analysis of all available data from the INTEGRAL, Swift, BeppoSAX
and XMM-Newton telescopes with a view to assessing the most likely counterpart
to the HESS source. We find that the energy source that fuels the X/gamma-ray
emissions is derived from the pulsar, both on the basis of the positional
morphology, the timing evidence and the energetics of the system. Likewise, the
1.2% of the pulsar's spin down energy loss needed to power the 0.1-10 TeV
emission is also fully consistent with other HESS sources known to be
associated with pulsars. The relative sizes of the X/gamma-ray and VHE sources
are consistent with the expected lifetimes against synchrotron and Compton
losses for a single source of parent electrons emitted from the pulsar. We find
that no other known object in the vicinity could be reasonably considered as a
plausible counterpart to the HESS source. We conclude that there is good
evidence to assume that the HESS J1616-508 source is driven by PSR J1617-5055
in which a combination of synchrotron and inverse Compton processes combine to
create the observed morphology of a broad-band emitter from keV to TeV
energies.Comment: 7 pages, including 5 figures and 1 table. Accepted for publication in
MNRA
Thermal-Fluid Flow Transport Phenomenon over Slot-Perforated Flat Plates Placed in Narrow Channel
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76151/1/AIAA-25872-119.pd
Spacetime structure of static solutions in Gauss-Bonnet gravity: neutral case
We study the spacetime structures of the static solutions in the
-dimensional Einstein-Gauss-Bonnet- system systematically. We
assume the Gauss-Bonnet coefficient is non-negative. The solutions
have the -dimensional Euclidean sub-manifold, which is the Einstein
manifold with the curvature and -1. We also assume , where is the curvature radius, in order for the
sourceless solution (M=0) to be defined. The general solutions are classified
into plus and minus branches. The structures of the center, horizons, infinity
and the singular point depend on the parameters , , ,
and branches complicatedly so that a variety of global structures for the
solutions are found. In the plus branch, all the solutions have the same
asymptotic structure at infinity as that in general relativity with a negative
cosmological constant. For the negative mass parameter, a new type of
singularity called the branch singularity appears at non-zero finite radius
. The divergent behavior around the singularity in Gauss-Bonnet
gravity is milder than that around the central singularity in general
relativity. In the cases the plus-branch solutions do not have any
horizon. In the case, the radius of the horizon is restricted as
) in the plus (minus)
branch. There is also the extreme black hole solution with positive mass in
spite of the lack of electromagnetic charge. We briefly discuss the effect of
the Gauss-Bonnet corrections on black hole formation in a collider and the
possibility of the violation of third law of the black hole thermodynamics.Comment: 19 pages, 11 figure
Perturbations of global monopoles as a black hole's hair
We study the stability of a spherically symmetric black hole with a global
monopole hair. Asymptotically the spacetime is flat but has a deficit solid
angle which depends on the vacuum expectation value of the scalar field. When
the vacuum expectation value is larger than a certain critical value, this
spacetime has a cosmological event horizon. We investigate the stability of
these solutions against the spherical and polar perturbations and confirm that
the global monopole hair is stable in both cases. Although we consider some
particular modes in the polar case, our analysis suggests the conservation of
the "topological charge" in the presence of the event horizons and violation of
black hole no-hair conjecture in asymptotically non-flat spacetime.Comment: 11 pages, 2 figures, some descriptions were improve
Abelian Higgs Hair for a Static Charged Black String
We study the problem of vortex solutions in the background of an electrically
charged black string. We show numerically that the Abelian Higgs field
equations in the background of a four-dimensional black string have vortex
solutions. These solutions which have axial symmetry, show that the black
string can support the Abelian Higgs field as hair. This situation holds also
in the case of the extremal black string. We also consider the self-gravity of
the Abelian Higgs field and show that the effect of the vortex is to induce a
deficit angle in the metric under consideration.Comment: REVTEX4, 12 pages, 6 figures, The version to be appeared in Phys.
Rev.
Optical Flow on Evolving Surfaces with an Application to the Analysis of 4D Microscopy Data
We extend the concept of optical flow to a dynamic non-Euclidean setting.
Optical flow is traditionally computed from a sequence of flat images. It is
the purpose of this paper to introduce variational motion estimation for images
that are defined on an evolving surface. Volumetric microscopy images depicting
a live zebrafish embryo serve as both biological motivation and test data.Comment: The final publication is available at link.springer.co
The properties of the putative pulsar associated with IGR J18135-1751/HESS J1813-178
Context: We investigate the possible theoretical properties of the putative
pulsar associated with the pulsar wind nebula IGR J18135-1751/HESS J1813-178
based upon recent gamma-ray observations and archival multi-wavelength
observations. Aims: We show that when using the standard equations for magnetic
dipole radiation with recent soft gamma-ray observations leads to deriving an
extreme set of parameters (magnetic field, period and spin down rate) for the
putative pulsar. Alternative scenarios that generate more typical parameter
values are explored. Methods: The properties of the putative pulsar are
calculated assuming that the 20-100 keV luminosity corresponds to 1% of Edot,
that the source is 4.5 kpc away, and that the pulsar age is 300 yrs. This gives
P = 0.55 s, Pdot = 3E-11 s/s, and B = 1.28E14 G. This is a very extreme set
compared to the population of known pulsars in PWN systems. Using the equations
for magnetic dipole losses makes it possible to adjust the initial assumptions
to see what is required for a more reasonable set of pulsar parameters.
Results: The current measured properties for IGR J18135-1751/HESS J1813-178
(i.e. luminosity, distance, and age) result in extreme properties of the unseen
pulsar within the PWN. The simplest method for achieving more reasonable
properties for the pulsar is to decouple the spin-down age of the pulsar from
the actual age for the system.Comment: 4 pages, 1 figure, accepted for publication as a Research Note in
Astronomy & Astrophysic
Systematic study of the decay rates of antiprotonic helium states
A systematic study of the decay rates of antiprotonic helium (\pbhef and
\pbhet) at CERN AD (Antiproton Decelerator) has been made by a laser
spectroscopic method. The decay rates of some of its short-lived states, namely
those for which the Auger rates are much larger than
their radiative decay rates ( s),
were determined from the time distributions of the antiproton annihilation
signals induced by laser beams, and the widths of the atomic resonance lines.
The magnitude of the decay rates, especially their relation with the transition
multipolarity, is discussed and compared with theoretical calculations.Comment: 6 pages, 5 figures, and 1 tabl
Dangerous implications of a minimum length in quantum gravity
The existence of a minimum length and a generalization of the Heisenberg
uncertainty principle seem to be two fundamental ingredients required in any
consistent theory of quantum gravity. In this letter we show that they would
predict dangerous processes which are phenomenologically unacceptable. For
example, long--lived virtual super--Planck mass black holes may lead to rapid
proton decay. Possible solutions of this puzzle are briefly discussed.Comment: 5 pages, no figure. v3: refereed versio
- …