9,267 research outputs found
The finite mass beamsplitter in high power interferometers
The beamplitter in high-power interferometers is subject to significant
radiation-pressure fluctuations. As a consequence, the phase relations which
appear in the beamsplitter coupling equations oscillate and phase modulation
fields are generated which add to the reflected fields. In this paper, the
transfer function of the various input fields impinging on the beamsplitter
from all four ports onto the output field is presented including
radiation-pressure effects. We apply the general solution of the coupling
equations to evaluate the input-output relations of the dual-recycled
laser-interferometer topology of the gravitational-wave detector GEO600 and the
power-recycling, signal-extraction topology of advanced LIGO. We show that the
input-output relation exhibits a bright-port dark-port coupling. This mechanism
is responsible for bright-port contributions to the noise density of the output
field and technical laser noise is expected to decrease the interferometer's
sensitivity at low frequencies. It is shown quantitatively that the issue of
technical laser noise is unimportant in this context if the interferometer
contains arm cavities.Comment: 10 pages, 7 figure
Gravitational waveforms for spinning compact binaries
The rotation of the bodies and the eccentricity of the orbit have significant
effects on the emitted gravitational radiation of binary systems. This work
focuses on the evaluation of the gravitational wave polarization states for
spinning compact binaries. We consider binaries on eccentric orbits and the
spin-orbit interaction up to the 1.5 post-Newtonian order in a way which is
independent of the parameterization of the orbit. The equations of motion for
angular variables are included. The formal expressions of the polarization
states are given with the inclusion of higher order corrections to the
waveform
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
Alien Registration- Caron, Joseph B. (Brunswick, Cumberland County)
https://digitalmaine.com/alien_docs/31513/thumbnail.jp
A Reinvestigation of Moving Punctured Black Holes with a New Code
We report on our code, in which the moving puncture method is applied and an
adaptive/fixed mesh refinement is implemented, and on its preliminary
performance on black hole simulations. Based on the BSSN formulation,
up-to-date gauge conditions and the modifications of the formulation are also
implemented and tested. In this work we present our primary results about the
simulation of a single static black hole, of a moving single black hole, and of
the head-on collision of a binary black hole system. For the static punctured
black hole simulations, different modifications of the BSSN formulation are
applied. It is demonstrated that both the currently used sets of modifications
lead to a stable evolution. For cases of a moving punctured black hole with or
without spin, we search for viable gauge conditions and study the effect of
spin on the black hole evolution. Our results confirm previous results obtained
by other research groups. In addition, we find a new gauge condition, which has
not yet been adopted by any other researchers, which can also give stable and
accurate black hole evolution calculations. We examine the performance of the
code for the head-on collision of a binary black hole system, and the agreement
of the gravitational waveform it produces with that obtained in other works. In
order to understand qualitatively the influence of matter on the binary black
hole collisions, we also investigate the same head-on collision scenarios but
perturbed by a scalar field. The numerical simulations performed with this code
not only give stable and accurate results that are consistent with the works by
other numerical relativity groups, but also lead to the discovery of a new
viable gauge condition, as well as clarify some ambiguities in the modification
of the BSSN formulation.Comment: 17 pages, 8 figures, accepted for publication in PR
Ge- en moyen-haut-allemand ou l'évitement du particulier et du temps incarné
During the Middle Ages, the prefix ge- was widely used in German, appearing in nouns, adjectives and verbs. These composed forms usually existed alongside their simple, unprefixed counterparts. Yet although the various compositional values are not difficult to determine for nouns, the same is not true of verbs. What was the function of ge- when used as a verbal prefix? Is it possible to link this non-nominal ge- to its nominal double, and to examine if the “unifying-and-totalizing” value of ge- (in nouns) also applies to verbs?
Preliminary results of the analysis and of the optimization dedicated to the final focus stabilization
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