2,419 research outputs found
Extreme Mass Ratio Binary: Radiation reaction and gravitational waveform
For a successful detection of gravitational waves by LISA, it is essential to
construct theoretical waveforms in a reliable manner. We discuss gravitational
waves from an extreme mass ratio binary system which is expected to be a
promising target of the LISA project.
The extreme mass ratio binary is a binary system of a supermassive black hole
and a stellar mass compact object. As the supermassive black hole dominates the
gravitational field of the system, we suppose that the system might be well
approximated by a metric perturbation of a Kerr black hole. We discuss a recent
theoretical progress in calculating the waveforms from such a system.Comment: Classical and Quantum Gravity 22 (2005) S375-S379, Proceedings for
5th International LISA Symposiu
From the self-force problem to the Radiation reaction formula
We review a recent theoretical progress in the so-called self-force problem
of a general relativistic two-body system. Although a two-body system in
Newtonian gravity is a very simple problem, some fundamental issues are
involved in relativistic gravity. Besides, because of recent projects for
gravitational wave detection, it comes to be possible to see those phenomena
directly via gravitational waves, and the self-force problem becomes one of
urgent and highly-motivated problems in general relativity. Roughly speaking,
there are two approaches to investigate this problem; the so-called
post-Newtonian approximation, and a black hole perturbation.
In this paper, we review a theoretical progress in the self-force problem
using a black hole perturbation. Although the self-force problem seems to be
just a problem to calculate a self-force, we discuss that the real problem is
to define a gauge invariant concept of a motion in a gauge dependent metric
perturbation.Comment: a special issue for Classical and Quantum Gravity, a review article
of Capra Ranch Meeting
Perturbative Approach to an orbital evolution around a Supermassive black hole
A charge-free, point particle of infinitesimal mass orbiting a Kerr black
hole is known to move along a geodesic. When the particle has a finite mass or
charge, it emits radiation which carries away orbital energy and angular
momentum, and the orbit deviates from a geodesic.
In this paper we assume that the deviation is small and show that the
half-advanced minus half-retarded field surprisingly provides the correct
radiation reaction force, in a time-averaged sense, and determines the orbit of
the particle.Comment: accepted for publication in the Physical Revie
Gauge Problem in the Gravitational Self-Force II. First Post Newtonian Force under Regge-Wheeler Gauge
We discuss the gravitational self-force on a particle in a black hole
space-time. For a point particle, the full (bare) self-force diverges. It is
known that the metric perturbation induced by a particle can be divided into
two parts, the direct part (or the S part) and the tail part (or the R part),
in the harmonic gauge, and the regularized self-force is derived from the R
part which is regular and satisfies the source-free perturbed Einstein
equations. In this paper, we consider a gauge transformation from the harmonic
gauge to the Regge-Wheeler gauge in which the full metric perturbation can be
calculated, and present a method to derive the regularized self-force for a
particle in circular orbit around a Schwarzschild black hole in the
Regge-Wheeler gauge. As a first application of this method, we then calculate
the self-force to first post-Newtonian order. We find the correction to the
total mass of the system due to the presence of the particle is correctly
reproduced in the force at the Newtonian order.Comment: Revtex4, 43 pages, no figure. Version to be published in PR
Quantum-Liouville and Langevin Equations for Gravitational Radiation Damping
From a forward--backward path integral, we derive a master equation for the
emission and absorption of gravitons by a massive quantum object in a heat bath
of gravitons. Such an equation could describe collapse phenomena of dense
stars. We also present a useful approximate Langevin equation for such a
system.Comment: Author Information under
http://www.physik.fu-berlin.de/~kleinert/institution.html . Latest update of
paper (including all PS fonts) at
http://www.physik.fu-berlin.de/~kleinert/31
Self-force via a Green's function decomposition
The gravitational field of a particle of small mass \mu moving through curved
spacetime is naturally decomposed into two parts each of which satisfies the
perturbed Einstein equations through O(\mu). One part is an inhomogeneous field
which, near the particle, looks like the \mu/r field distorted by the local
Riemann tensor; it does not depend on the behavior of the source in either the
infinite past or future. The other part is a homogeneous field and includes the
``tail term''; it completely determines the self force effects of the particle
interacting with its own gravitational field, including radiation reaction.
Self force effects for scalar, electromagnetic and gravitational fields are all
described in this manner.Comment: PRD, in press. Enhanced emphasis on the equivalence principl
The Transition from Inspiral to Plunge for a Compact Body in a Circular Equatorial Orbit Around a Massive, Spinning Black Hole
There are three regimes of gravitational-radiation-reaction-induced inspiral
for a compact body with mass mu, in a circular, equatorial orbit around a Kerr
black hole with mass M>>mu: (i) The "adiabatic inspiral regime", in which the
body gradually descends through a sequence of circular, geodesic orbits. (ii) A
"transition regime", near the innermost stable circular orbit (isco). (iii) The
"plunge regime", in which the body travels on a geodesic from slightly below
the isco into the hole's horizon. This paper gives an analytic treatment of the
transition regime and shows that, with some luck, gravitational waves from the
transition might be measurable by the space-based LISA mission.Comment: 8 Pages and 3 Figures; RevTeX; submitted to Physical Review
A multidisciplinary approach using LCCA and micro-simulation 10 model for the management of the urban pavements
The maintenance and the rehabilitation of the urban road pavements are not often based on
systematic program and scheduling but rather on emergency or on other not identified reasons.
Moreover the Life Cycle Cost Analysis (LCCA), the only peculiar procedure for the
management pavement, finds its own application for highway and motorway, even if it is
possible to search the best investment for the urban interstate and arterials.
By the light of the quantity of the involved resources, it seems necessary to define an operative
methodology for programming the maintenance and rehabilitation activities for the urban
pavement. The paper is oriented towards the development of a multidisciplinary approach to
make decision on management of urban pavement using the basic concepts of the LCCA and
micro-simulation model to define a scheme of work zone that minimizes the delay on the traffic
flow.
The best rehabilitation strategy should be characterized by the lowest users\u2019 cost that depends on
the time period of the work zone, which is conditioned by both own scheme and the provided
treatment, and on \u201csocial cost\u201d as increased travel time for queue generation .
Different scenarios for different work zone plans were developed and a micro-simulation model
was used to assess increased total travel time of a traffic flow within the maintenance area.
In this work an analysis by means of the above mentioned approach was carried out on real scenario in the city of Palermo in order to point out the several frames of the adopted
methodology
B_K with the Wilson Quark Action: A Non-Perturbative Resolution of Operator Mixing using Chiral Ward Identities
We propose a non-perturbative method to determine the mixing coefficients of
four-quark operators for the Wilson quark action using chiral Ward
identities. The method is applied to calculate B_K in quenched QCD.Comment: 3 pages including 3 figures, Talk presented at
LATTICE96(phenomenology) by Y. Kuramash
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