81 research outputs found
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
Robust statistics for deterministic and stochastic gravitational waves in non-Gaussian noise I: Frequentist analyses
Gravitational wave detectors will need optimal signal-processing algorithms
to extract weak signals from the detector noise. Most algorithms designed to
date are based on the unrealistic assumption that the detector noise may be
modeled as a stationary Gaussian process. However most experiments exhibit a
non-Gaussian ``tail'' in the probability distribution. This ``excess'' of large
signals can be a troublesome source of false alarms. This article derives an
optimal (in the Neyman-Pearson sense, for weak signals) signal processing
strategy when the detector noise is non-Gaussian and exhibits tail terms. This
strategy is robust, meaning that it is close to optimal for Gaussian noise but
far less sensitive than conventional methods to the excess large events that
form the tail of the distribution. The method is analyzed for two different
signal analysis problems: (i) a known waveform (e.g., a binary inspiral chirp)
and (ii) a stochastic background, which requires a multi-detector signal
processing algorithm. The methods should be easy to implement: they amount to
truncation or clipping of sample values which lie in the outlier part of the
probability distribution.Comment: RevTeX 4, 17 pages, 8 figures, typos corrected from first version
Advanced LIGO's ability to detect apparent violations of the cosmic censorship conjecture and the no-hair theorem through compact binary coalescence detections
We study the ability of the advanced Laser Interferometer Gravitational-wave
Observatory (aLIGO) to detect apparent violations of the cosmic censorship
conjecture and the no-hair theorem. The cosmic censorship conjecture, which is
believed to be true in the theory of general relativity, limits the
spin-to-mass-squared ratio of a Kerr black hole. The no-hair theorem, which is
also believed to be true in the theory of general relativity, suggests a
particular value for the tidal Love number of a non-rotating black hole. Using
the Fisher matrix formalism, we examine the measurability of the spin and tidal
deformability of compact binary systems involving at least one putative black
hole. Using parameter measurement errors and correlations obtained from the
Fisher matrix, we determine the smallest detectable violation of bounds implied
by the cosmic censorship conjecture and the no-hair theorem. We examine the
effect of excluding unphysical areas of parameter space when determining the
smallest detectable apparent violations, and we examine the effect of different
post-Newtonian corrections to the amplitude of the compact binary coalescence
gravitational waveform. In addition, we perform a brief study of how the
recently calculated 3.0 pN and 3.5 pN spin-orbit corrections to the phase
affect spin and mass parameter measurability. We find that physical priors on
the symmetric mass ratio and higher harmonics in the gravitational waveform
could significantly affect the ability of aLIGO to investigate cosmic
censorship and the no-hair theorem for certain systems.Comment: 21 pages, 7 figures, 6 table
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
FINDCHIRP: an algorithm for detection of gravitational waves from inspiraling compact binaries
Matched-filter searches for gravitational waves from coalescing compact
binaries by the LIGO Scientific Collaboration use the FINDCHIRP algorithm: an
implementation of the optimal filter with innovations to account for unknown
signal parameters and to improve performance on detector data that has
nonstationary and non-Gaussian artifacts. We provide details on the FINDCHIRP
algorithm as used in the search for subsolar mass binaries, binary neutron
stars, neutron star-black hole binaries, and binary black holes.Comment: 19 pages, 1 figure, journal version with Creative Commons 4.0
open-access license adde
A power filter for the detection of burst sources of gravitational radiation in interferometric detectors
We present a filter for detecting gravitational wave signals from burst
sources. This filter requires only minimal advance knowledge of the expected
signal: i.e. the signal's frequency band and time duration. It consists of a
threshold on the total power in the data stream in the specified signal band
during the specified time. This filter is optimal (in the Neyman-Pearson sense)
for signal searches where only this minimal information is available.Comment: 3 pages, RevTeX, GWDAW '99 proceedings contribution, submitted to
Int. J. Modern Phys.
Inferring the neutron star equation of state from binary inspiral waveforms
The properties of neutron star matter above nuclear density are not precisely
known. Gravitational waves emitted from binary neutron stars during their late
stages of inspiral and merger contain imprints of the neutron-star equation of
state. Measuring departures from the point-particle limit of the late inspiral
waveform allows one to measure properties of the equation of state via
gravitational wave observations. This and a companion talk by J. S. Read
reports a comparison of numerical waveforms from simulations of inspiraling
neutron-star binaries, computed for equations of state with varying stiffness.
We calculate the signal strength of the difference between waveforms for
various commissioned and proposed interferometric gravitational wave detectors
and show that observations at frequencies around 1 kHz will be able to measure
a compactness parameter and constrain the possible neutron-star equations of
state.Comment: Talk given at the 12th Marcel Grossman Meeting, Paris, France, 12-18
Jul 200
Localization of binary neutron star mergers with a single Cosmic Explorer
Next-generation ground-based gravitational-wave detectors, such as Cosmic
Explorer (CE), are expected to be sensitive to gravitational-wave signals with
frequencies as low as 5 Hz, allowing signals to spend a significant amount of
time in the detector frequency band. As a result, the effects caused by the
rotation of the Earth become increasingly important for such signals.
Additionally, the length of the arms of these detectors can be comparable to
the wavelength of detectable gravitational waves, which introduces
frequency-dependent effects that are not significant in current-generation
detectors. These effects are expected to improve the ability to localize
compact binary coalescences in the sky even when using only one detector. This
study aims to understand how much these effects can help in localization. We
present the first comprehensive Bayesian parameter estimation framework that
accounts for all these effects using \textsc{Bilby}, a commonly used Bayesian
parameter estimation tool. We focus on sky localization constraints for binary
neutron star events with an optimal signal-to-noise ratio of 1000 with one
detector at the projected CE sensitivity. We find that these effects help
localize sources using one detector with sky areas as low as 10 square degrees.
Moreover, we explore and discuss how ignoring these effects in the parameter
estimation can lead to biases in the inference.Comment: Version accepted by PR
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