576 research outputs found
Black hole singularities: a numerical approach
The singularity structure of charged spherical collapse is studied by
considering the evolution of the gravity-scalar field system. A detailed
examination of the geometry at late times strongly suggests the validity of the
mass-inflation scenario~\cite{PI:90}. Although the area of the two-spheres
remains finite at the Cauchy horizon, its generators are eventually focused to
zero radius. Thus the null, mass-inflation singularity {\em generally}\/
precedes a crushing singularity deep inside the black hole core. This
central singularity is spacelike.Comment: 4 pages Phys. Rev. style including five figures, provided as
compressed postscript files. To appear in Physical Review Letter
Computing the merger of black-hole binaries: the IBBH problem
Gravitational radiation arising from the inspiral and merger of binary black
holes (BBH's) is a promising candidate for detection by kilometer-scale
interferometric gravitational wave observatories. This paper discusses a
serious obstacle to searches for such radiation and to the interpretation of
any observed waves: the inability of current computational techniques to evolve
a BBH through its last ~10 orbits of inspiral (~100 radians of
gravitational-wave phase). A new set of numerical-relativity techniques is
proposed for solving this ``Intermediate Binary Black Hole'' (IBBH) problem:
(i) numerical evolutions performed in coordinates co-rotating with the BBH, in
which the metric coefficients evolve on the long timescale of inspiral, and
(ii) techniques for mathematically freezing out gravitational degrees of
freedom that are not excited by the waves.Comment: 6 pages RevTe
Optimal Strategies for Sinusoidal Signal Detection
We derive and study optimal and nearly-optimal strategies for the detection
of sinusoidal signals hidden in additive (Gaussian and non-Gaussian) noise.
Such strategies are an essential part of algorithms for the detection of the
gravitational Continuous Wave
(CW) signals produced by pulsars. Optimal strategies are derived for the case
where the signal phase is not known and the product of the signal frequency and
the observation time is non-integral.Comment: 18 pages, REVTEX4, 7 figures, 2 table
The Loudest Event Statistic: General Formulation, Properties and Applications
The use of the loudest observed event to generate statistical statements
about rate and strength has become standard in searches for gravitational waves
from compact binaries and pulsars. The Bayesian formulation of the method is
generalized in this paper to allow for uncertainties both in the background
estimate and in the properties of the population being constrained. The method
is also extended to allow rate interval construction. Finally, it is shown how
to combine the results from multiple experiments and a comparison is drawn
between the upper limit obtained in a single search and the upper limit
obtained by combining the results of two experiments each of half the original
duration. To illustrate this, we look at an example case, motivated by the
search for gravitational waves from binary inspiral.Comment: 11 pages, 8 figure
Upper limits on gravitational-wave signals based on loudest events
Searches for gravitational-wave bursts have often focused on the loudest
event(s) in searching for detections and in determining upper limits on
astrophysical populations. Typical upper limits have been reported on event
rates and event amplitudes which can then be translated into constraints on
astrophysical populations. We describe the mathematical construction of such
upper limits.Comment: 8 pages, 1 figur
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