3,087 research outputs found
Pulsar Magnetosphere : A General Relativistic Treatment
A fully general relativistic description of the pulsar magnetosphere is
provided. To be more concrete, a study of the pulsar magnetosphere is performed
in the context of general relativistic magnetohydrodynamics (MHD) employing the
so-called Grad-Shafranov approach. Not surprisingly, the resulting
Grad-Shafranov equations and all the other related general relativistic MHD
equations turn out to take essentially the same structures as those for the
(rotating) black hole magnetosphere. Other different natures between the two
cases including the structure of singular surfaces of MHD flows in each
magnetosphere are essentially encoded in the different spacetime (metric)
contents. In this way, the pulsar and the black hole magnetospheres can be
described in an unified fashion. Particularly, the direction of poloidal
currents circulating in the neutron star magnetosphere turns out to be the same
as that of currents circulating in the black hole magnetosphere which, in turn,
leads to the pulsar and the black hole spin-downs via the ``magnetic braking''.Comment: 42 pages, 3 figures, Mon. Not. R. Astron. Soc.(MNRAS), in pres
Spacetime structure of 5D hypercylindrical vacuum solutions with tension
We investigate geometrical properties of 5D cylindrical vacuum solutions with
a transverse spherical symmetry. The metric is uniform along the fifth
direction and characterized by tension and mass densities. The solutions are
classified by the tension-to-mass ratio. One particular example is the
well-known Schwarzschild black string which has a curvature singularity
enclosed by a horizon. We focus mainly on geometry of other solutions which
possess a naked singularity. The light signal emitted by an object approaching
the singularity reaches a distant observer with finite time, but is infinitely
red-shifted.Comment: revtex4, 5 pages, 2 figures. To appear in the proceedings of the 10th
Asia Pacific Physics Conference (APPC10), Pohang, Korea, 21-24 Aug. 2007.
Submitted to J. Korean Phys. Soc. Penrose diagram has been adde
Cosmic Microwave Background Radiation anisotropy with primordial magnetic fields
Galactic magnetic fields are observed of order , but their
origin is not definitely known yet. In this paper we consider the primordial
magnetic fields generated in the early universe and analyse their effects on
the density perturbations and the CMBR anisotropy. We assume that the random
magnetic fields have the power law spectrum and satisfy the force-free field
condition.
The peak heights of the CMBR anisotropy are shown to be shifted upward
depending on the magnetic field strengths relative to the no-magnetic field
case.Comment: 22 pages, 5 figure
Instanton solutions mediating tunneling between the degenerate vacua in curved space
We investigate the instanton solution between the degenerate vacua in curved
space. We show that there exist -symmetric solutions not only in de
Sitter but also in both flat and anti-de Sitter space. The geometry of the new
type of solutions is finite and preserves the symmetry. The nontrivial
solution corresponding to the tunneling is possible only if gravity is taken
into account. The numerical solutions as well as the analytic computations
using the thin-wall approximation are presented. We expect that these solutions
do not have any negative mode as in the instanton solution.Comment: Some typos are corrected and references are added with respect to the
published version. 17pages, 11fi
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