3,133 research outputs found
Polar Perturbations of Self-gravitating Supermassive Global Monopoles
Spontaneous global symmetry breaking of O(3) scalar field gives rise to
point-like topological defects, global monopoles. By taking into account
self-gravity,the qualitative feature of the global monopole solutions depends
on the vacuum expectation value v of the scalar field. When v < sqrt{1 / 8 pi},
there are global monopole solutions which have a deficit solid angle defined at
infinity. When sqrt{1 / 8 pi} <= v < sqrt{3 / 8 pi}, there are global monopole
solutions with the cosmological horizon, which we call the supermassive global
monopole. When v >= sqrt{3 / 8 pi}, there is no nontrivial solution. It was
shown that all of these solutions are stable against the spherical
perturbations. In addition to the global monopole solutions, the de Sitter
solutions exist for any value of v. They are stable against the spherical
perturbations when v sqrt{3 / 8 pi}.
We study polar perturbations of these solutions and find that all
self-gravitating global monopoles are stable even against polar perturbations,
independently of the existence of the cosmological horizon, while the de Sitter
solutions are always unstable.Comment: 10 pages, 6 figures, corrected some type mistakes (already corrected
in PRD version
Observation of an energetic radiation burst from mountain-top thunderclouds
During thunderstorms on 2008 September 20, a simultaneous detection of gamma
rays and electrons was made at a mountain observatory in Japan located 2770 m
above sea level. Both emissions, lasting 90 seconds, were associated with
thunderclouds rather than lightning. The photon spectrum, extending to 10 MeV,
can be interpreted as consisting of bremsstrahlung gamma rays arriving from a
source which is 60 - 130 m in distance at 90% confidence level. The observed
electrons are likely to be dominated by a primary population escaping from an
acceleration region in the clouds.Comment: 12 pages, 3 figures, accepted for publication in Physical Review
Letter
Abelian Higgs Hair for Rotating and Charged Black Holes
We study the problem of vortex solutions in the background of rotating black
holes in both asymptotically flat and asymptoticlly anti de Sitter spacetimes.
We demonstrate the Abelian Higgs field equations in the background of four
dimensional Kerr, Kerr-AdS and Reissner-Nordstrom-AdS black holes have vortex
line solutions. These solutions, which have axial symmetry, are generalization
of the Nielsen-Olesen string. By numerically solving the field equations in
each case, we find that these black holes can support an Abelian Higgs field as
hair. This situation holds even in the extremal case, and no flux-expulsion
occurs. We also compute the effect of the self gravity of the Abelian Higgs
field show that the the vortex induces a deficit angle in the corresponding
black hole metrics.Comment: 22 pages, 16 figures, a section about the vortex self gravity on Kerr
black hole added, extremal black holes considered, one figure changed, one
reference adde
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
Generic differential geometry of hyperbolic plane curves
We study hyperbolic invariants of hyperbolic plane curves as applications of the singularity theory of smooth function
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