13,386 research outputs found
Regularization of static self-forces
Various regularization methods have been used to compute the self-force
acting on a static particle in a static, curved spacetime. Many of these are
based on Hadamard's two-point function in three dimensions. On the other hand,
the regularization method that enjoys the best justification is that of
Detweiler and Whiting, which is based on a four-dimensional Green's function.
We establish the connection between these methods and find that they are all
equivalent, in the sense that they all lead to the same static self-force. For
general static spacetimes, we compute local expansions of the Green's functions
on which the various regularization methods are based. We find that these agree
up to a certain high order, and conjecture that they might be equal to all
orders. We show that this equivalence is exact in the case of ultrastatic
spacetimes. Finally, our computations are exploited to provide regularization
parameters for a static particle in a general static and spherically-symmetric
spacetime.Comment: 23 pages, no figure
Self force on static charges in Schwarzschild spacetime
We study the self forces acting on static scalar and electric test charges in
the spacetime of a Schwarzschild black hole. The analysis is based on a direct,
local calculation of the self forces via mode decomposition, and on two
independent regularization procedures: A spatially-extended particle model
method, and on a mode-sum regularization prescription. In all cases we find
excellent agreement with the known exact results.Comment: 21 pages, 9 Encapsulated PostScript figures, submitted to Class.
Quantum Gra
Charged particles in higher dimensional homogeneous gravitational field: Self-energy and self-force
A problem of self-energy and self-force for a charged point-like particle in
a higher dimensional homogeneous gravitational field is considered. We study
two cases, when a particle has usual electric charge and a case when it has a
scalar charge, which is a source of a scalar massless minimally coupled field.
We assume that a particle is at rest in the gravitational field, so that its
motion is not geodesic and it has an acceleration a directed from the horizon.
The self-energy of a point charge is divergent and the strength of the
divergence grows with the number of dimensions. In order to obtain a finite
contribution to the self- energy we use a covariant regularization method which
is a modification of the proper time cut-off and other covariant
regularizations. We analyze a relation between the self-energy and self-force
and obtain explicit expressions for the self-forces for the electric and scalar
charge in the spacetimes with the number of dimensions up to eight. General
expressions for the case of higher dimensions are also obtained. We discuss
special logarithmic factors ln(a), which are present both in the self-energy
and self-force in odd dimensions. Finally, we compare the obtained results with
the earlier known results both for the homogeneous gravitational field and for
particles near black holes.Comment: 43 pages, two subsections added, a few tables and references adde
Self force on a scalar charge in the spacetime of a stationary, axisymmetric black hole
We study the self force acting on a particle endowed with scalar charge,
which is held static (with respect to an undragged, static observer at
infinity) outside a stationary, axially-symmetric black hole. We find that the
acceleration due to the self force is in the same direction as the black hole's
spin, and diverges when the particle approaches the outer boundary of the black
hole's ergosphere. This acceleration diverges more rapidly approaching the
ergosphere's boundary than the particle's acceleration in the absence of the
self force. At the leading order this self force is a (post)-Newtonian
effect. For scalar charges with high charge-to-mass ratio, the acceleration due
to the self force starts dominating over the regular acceleration already far
from the black hole. The self force is proportional to the rate at which the
black hole's rotational energy is dissipated. This self force is local (i.e.,
only the Abraham-Lorentz-Dirac force and the local coupling to Ricci curvature
contribute to it). The non-local, tail part of the self force is zero.Comment: 28 pages, 9 figure
Self force on particle in orbit around a black hole
We study the self force acting on a scalar charge in uniform circular motion
around a Schwarzschild black hole. The analysis is based on a direct
calculation of the self force via mode decomposition, and on a regularization
procedure based on Ori's mode-sum regularization prescription. We find the four
self-force at arbitrary radii and angular velocities (both geodesic and
non-geodesic), in particular near the black hole, where general-relativistic
effects are strongest, and for fast motion. We find the radial component of the
self force to be repulsive or attractive, depending on the orbit.Comment: RevTeX, 4 pages, 4 Encapsulated PostScript figures. Submitted to
Phys. Rev. Let
Self-force approach for radiation reaction
We overview the recently proposed mode-sum regularization prescription (MSRP)
for the calculation of the local radiation-reaction forces, which are crucial
for the orbital evolution of binaries. We then describe some new results which
were obtained using MSRP, and discuss their importance for gravitational-wave
astronomy.Comment: Talk given at the 3rd Edoardo Amaldi Conference on Gravitational
Waves, 12-16 July, 199
- …