568 research outputs found
The Hyperfine Einstein-Infeld-Hoffmann Potential
We use recently developed effective field theory techniques to calculate the
third order post-Newtonian correction to the spin-spin potential between two
spinning objects. This correction represents the first contribution to the
spin-spin interaction due to the non-linear nature of general relativity and
will play an important role in forthcoming gravity wave experiments.Comment: 4 pages, 2 figures, RevTe
Measured limits to contamination of optical surfaces by elastomers in vacuum
We have monitored the reflectivity of mirrors that were exposed to a fluoroelastomer (3M-Fluorel 2176) and a room-temperature vulcanizing silicone rubber (RTV-615) in vacuum. The 95% confidence limit on the decrease of mirror reflectivities was less than 0.35 ppm/week for Fluorel and <0.29 ppm@week for RTV-615
The influence of differential rotation on the detectability of gravitational waves from the r-mode instability
Recently, it was shown that differential rotation is an unavoidable feature
of nonlinear r-modes. We investigate the influence of this differential
rotation on the detectability of gravitational waves emitted by a newly born,
hot, rapidly-rotating neutron star, as it spins down due to the r-mode
instability. We conclude that gravitational radiation may be detected by the
advanced laser interferometer detector LIGO if the amount of differential
rotation at the time the r-mode instability becomes active is not very high.Comment: 8 pages, 6 figures, revtex
Information-theory-based solution of the inverse problem in classical statistical mechanics
We present a procedure for the determination of the interaction potential
from the knowledge of the radial pair distribution function. The method,
realized inside an inverse Monte Carlo simulation scheme, is based on the
application of the Maximum Entropy Principle of information theory and the
interaction potential emerges as the asymptotic expression of the transition
probability. Results obtained for high density monoatomic fluids are very
satisfactory and provide an accurate extraction of the potential, despite a
modest computational effort.Comment: 9 pages, 2 figure
Gravitational Wave Astrometry for Rapidly Rotating Neutron Stars and Estimation of Their Distances
We discuss an astrometric timing effect on data analysis of continuous
gravitational waves from rapidly rotating isolated neutron stars. Special
attention is directed to the possibility of determining their distances by
measuring the curvature of the wave fronts. We predict that if continuous
gravitational waves from an unknown neutron star with a stable rotation are
detected around 1kHz within 1/3yr by initial LIGO detectors and the ellipticity
parameter epsilon is smaller than 10^{-6}, the distance r to the source can be
estimated with relative error \Delta r/r of \sim 10% by using the broad band
configuration of advanced LIGO detectors over 3 years. By combining the
observed amplitude of the waves with the estimated distance, information on the
parameter can be obtained purely through gravitational wave
measurements.Comment: 6 pages, 1 figure, to appear in PR
Transition from inspiral to plunge in precessing binaries of spinning black holes
We investigate the non-adiabatic dynamics of spinning black hole binaries by
using an analytical Hamiltonian completed with a radiation-reaction force,
containing spin couplings, which matches the known rates of energy and angular
momentum losses on quasi-circular orbits. We consider both a straightforward
post-Newtonian-expanded Hamiltonian (including spin-dependent terms), and a
version of the resummed post-Newtonian Hamiltonian defined by the Effective
One-Body approach. We focus on the influence of spin terms onto the dynamics
and waveforms. We evaluate the energy and angular momentum released during the
final stage of inspiral and plunge. For an equal-mass binary the energy
released between 40Hz and the frequency beyond which our analytical treatment
becomes unreliable is found to be, when using the more reliable Effective
One-Body dynamics: 0.6% M for anti-aligned maximally spinning black holes, 5% M
for aligned maximally spinning black hole, and 1.8% M for non-spinning
configurations. In confirmation of previous results, we find that, for all
binaries considered, the dimensionless rotation parameter J/E^2 is always
smaller than unity at the end of the inspiral, so that a Kerr black hole can
form right after the inspiral phase. By matching a quasi-normal mode ringdown
to the last reliable stages of the plunge, we construct complete waveforms
approximately describing the gravitational wave signal emitted by the entire
process of coalescence of precessing binaries of spinning black holes.Comment: 31 pages, 7 tables, and 13 figure
Displacement- and Timing-Noise Free Gravitational-Wave Detection
Motivated by a recently-invented scheme of displacement-noise-free
gravitational-wave detection, we demonstrate the existence of
gravitational-wave detection schemes insusceptible to both displacement and
timing (laser) noises, and are thus realizable by shot-noise-limited laser
interferometry. This is possible due to two reasons: first, gravitational waves
and displacement disturbances contribute to light propagation times in
different manners; second, for an N-detector system, the number of signal
channels is of the order O(N^2), while the total number of timing- and
displacement-noise channels is of the order O(N).Comment: 4 pages, 3 figures; mistake correcte
The Shapiro Conjecture: Prompt or Delayed Collapse in the head-on collision of neutron stars?
We study the question of prompt vs. delayed collapse in the head-on collision
of two neutron stars. We show that the prompt formation of a black hole is
possible, contrary to a conjecture of Shapiro which claims that collapse is
delayed until after neutrino cooling. We discuss the insight provided by
Shapiro's conjecture and its limitation. An understanding of the limitation of
the conjecture is provided in terms of the many time scales involved in the
problem. General relativistic simulations in the Einstein theory with the full
set of Einstein equations coupled to the general relativistic hydrodynamic
equations are carried out in our study.Comment: 4 pages, 7 figure
Gravitational wave bursts from cosmic (super)strings: Quantitative analysis and constraints
We discuss data analysis techniques that can be used in the search for
gravitational wave bursts from cosmic strings. When data from multiple
interferometers are available, we describe consistency checks that can be used
to greatly reduce the false alarm rates. We construct an expression for the
rate of bursts for arbitrary cosmic string loop distributions and apply it to
simple known solutions. The cosmology is solved exactly and includes the
effects of a late-time acceleration. We find substantially lower burst rates
than previous estimates suggest and explain the disagreement. Initial LIGO is
unlikely to detect field theoretic cosmic strings with the usual loop sizes,
though it may detect cosmic superstrings as well as cosmic strings and
superstrings with non-standard loop sizes (which may be more realistic). In the
absence of a detection, we show how to set upper limits based on the loudest
event. Using Initial LIGO sensitivity curves, we show that these upper limits
may result in interesting constraints on the parameter space of theories that
lead to the production of cosmic strings.Comment: Replaced with version accepted for publication in PR
QND and higher order effects for a nonlinear meter in an interferometric gravitational wave antenna
A new optical topology and signal readout strategy for a laser interferometer
gravitational wave detector were proposed recently by Braginsky and Khalili .
Their method is based on using a nonlinear medium inside a microwave oscillator
to detect the gravitational-wave-induced spatial shift of the interferometer's
standing optical wave. This paper proposes a quantum nondemolition (QND) scheme
that could be realistically used for such a readout device and discusses a
"fundamental" sensitivity limit imposed by a higher order optical effect.Comment: LaTex, 17 pages, 3 figure
- …