33 research outputs found
Survival of the black hole's Cauchy horizon under non-compact perturbations
We study numerically the evolution of spactime, and in particular of a
spacetime singularity, inside a black hole under a class of perturbations of
non-compact support. We use a very simplified toy model of a spherical charged
black hole which is perturbed nonlinearly by a self-gravitating, spherical
scalar field. The latter grows logarithmically with advanced time along an
outgoing characteristic hypersurface. We find that for that class of
perturbations a portion of the Cauchy horizon survives as a non-central, null
singularity.Comment: 5 pages, 4 figure
Orbital evolution of a particle around a black hole: II. Comparison of contributions of spin-orbit coupling and the self force
We consider the evolution of the orbit of a spinning compact object in a
quasi-circular, planar orbit around a Schwarzschild black hole in the extreme
mass ratio limit. We compare the contributions to the orbital evolution of both
spin-orbit coupling and the local self force. Making assumptions on the
behavior of the forces, we suggest that the decay of the orbit is dominated by
radiation reaction, and that the conservative effect is typically dominated by
the spin force. We propose that a reasonable approximation for the
gravitational waveform can be obtained by ignoring the local self force, for
adjusted values of the parameters of the system. We argue that this
approximation will only introduce small errors in the astronomical
determination of these parameters.Comment: 11 pages, 7 figure
Universality of massive scalar field late-time tails in black-hole spacetimes
The late-time tails of a massive scalar field in the spacetime of black holes
are studied numerically. Previous analytical results for a Schwarzschild black
hole are confirmed: The late-time behavior of the field as recorded by a static
observer is given by , where
depends weakly on time. This result is carried over to the case of
a Kerr black hole. In particular, it is found that the power-law index of -5/6
depends on neither the multipole mode nor on the spin rate of the black
hole . In all black hole spacetimes, massive scalar fields have the same
late-time behavior irrespective of their initial data (i.e., angular
distribution). Their late-time behavior is universal.Comment: 11 pages, 14 figures, published versio
Effects of Pair Creation on Charged Gravitational Collapse
We investigate the effects of pair creation on the internal geometry of a
black hole, which forms during the gravitational collapse of a charged massless
scalar field. Classically, strong central Schwarzschild-like singularity forms,
and a null, weak, mass-inflation singularity arises along the Cauchy horizon,
in such a collapse. We consider here the discharge, due to pair creation, below
the event horizon and its influence on the {\it dynamical formation} of the
Cauchy horizon. Within the framework of a simple model we are able to trace
numerically the collapse. We find that a part of the Cauchy horizon is replaced
by the strong space-like central singularity. This fraction depends on the
value of the critical electric field, , for the pair creation.Comment: LaTex, 27 pages, including 14 figures. Some points are clarified,
typos corrected. Version accepted for publication in Phys.Rev.
Massive-Field Approach to the Scalar Self Force in Curved Spacetime
We derive a new regularization method for the calculation of the (massless)
scalar self force in curved spacetime. In this method, the scalar self force is
expressed in terms of the difference between two retarded scalar fields: the
massless scalar field, and an auxiliary massive scalar field. This field
difference combined with a certain limiting process gives the expression for
the scalar self-force. This expression provides a new self force calculation
method.Comment: 23 pages, few modification
Mass loss by a scalar charge in an expanding universe
We study the phenomenon of mass loss by a scalar charge -- a point particle
that acts a source for a noninteracting scalar field -- in an expanding
universe. The charge is placed on comoving world lines of two cosmological
spacetimes: a de Sitter universe, and a spatially-flat, matter-dominated
universe. In both cases, we find that the particle's rest mass is not a
constant, but that it changes in response to the emission of monopole scalar
radiation by the particle. In de Sitter spacetime, the particle radiates all of
its mass within a finite proper time. In the matter-dominated cosmology, this
happens only if the charge of the particle is sufficiently large; for smaller
charges the particle first loses some of its mass, but then regains it all
eventually.Comment: 11 pages, RevTeX4, Accepted for Phys. Rev.
Radiation tails and boundary conditions for black hole evolutions
In numerical computations of Einstein's equations for black hole spacetimes,
it will be necessary to use approximate boundary conditions at a finite
distance from the holes. We point out here that ``tails,'' the inverse
power-law decrease of late-time fields, cannot be expected for such
computations. We present computational demonstrations and discussions of
features of late-time behavior in an evolution with a boundary condition.Comment: submitted to Phys. Rev.
Radiative falloff in the background of rotating black hole
We study numerically the late-time tails of linearized fields with any spin
in the background of a spinning black hole. Our code is based on the
ingoing Kerr coordinates, which allow us to penetrate through the event
horizon. The late time tails are dominated by the mode with the least multipole
moment which is consistent with the equatorial symmetry of the initial
data and is equal to or greater than the least radiative mode with and the
azimuthal number .Comment: 5 pages, 4 Encapsulated PostScript figures; Accepted to Phys. Rev. D
(Rapid Communication
Massive fields tend to form highly oscillating self-similarly expanding shells
The time evolution of self-interacting spherically symmetric scalar fields in
Minkowski spacetime is investigated based on the use of Green's theorem. It is
shown that a massive Klein-Gordon field can be characterized by the formation
of certain expanding shell structures where all the shells are built up by very
high frequency oscillations. This oscillation is found to be modulated by the
product of a simple time decaying factor of the form and of an
essentially self-similar expansion. Apart from this self-similar expansion the
developed shell structure is preserved by the evolution. In particular, the
energy transported by each shell appears to be time independent.Comment: 10 pages, to appear in Phys. Rev.