994 research outputs found
Coherent Waveform Consistency Test for LIGO Burst Candidates
The burst search in LIGO relies on the coincident detection of transient
signals in multiple interferometers. As only minimal assumptions are made about
the event waveform or duration, the analysis pipeline requires loose
coincidence in time, frequency and amplitude. Confidence in the resulting
events and their waveform consistency is established through a time-domain
coherent analysis: the r-statistic test.
This paper presents a performance study of the r-statistic test for triple
coincidence events in the second LIGO Science Run (S2), with emphasis on its
ability to suppress the background false rate and its efficiency at detecting
simulated bursts of different waveforms close to the S2 sensitivity curve.Comment: 11 pages, 9 figures. Submitted to the Proceedings of the 8th
Gravitational Wave Data Analysis Workshop, in Classic and Quantum Gravit
Detection of gravitational-wave bursts with chirplet-like template families
Gravitational Wave (GW) burst detection algorithms typically rely on the
hypothesis that the burst signal is "locally stationary", that is it changes
slowly with frequency. Under this assumption, the signal can be decomposed into
a small number of wavelets with constant frequency. This justifies the use of a
family of sine-Gaussian templates in the Omega pipeline, one of the algorithms
used in LIGO-Virgo burst searches. However there are plausible scenarios where
the burst frequency evolves rapidly, such as in the merger phase of a binary
black hole and/or neutron star coalescence. In those cases, the local
stationarity of sine-Gaussians induces performance losses, due to the mismatch
between the template and the actual signal. We propose an extension of the
Omega pipeline based on chirplet-like templates. Chirplets incorporate an
additional parameter, the chirp rate, to control the frequency variation. In
this paper, we show that the Omega pipeline can easily be extended to include a
chirplet template bank. We illustrate the method on a simulated data set, with
a family of phenomenological binary black-hole coalescence waveforms embedded
into Gaussian LIGO/Virgo-like noise. Chirplet-like templates result in an
enhancement of the measured signal-to-noise ratio.Comment: 8 pages, 6 figures. Submitted to Class. Quantum Grav. Special issue:
Proceedings of GWDAW-14, Rome (Italy), 2010; fixed several minor issue
Gravitational Wave Burst Source Direction Estimation using Time and Amplitude Information
In this article we study two problems that arise when using timing and
amplitude estimates from a network of interferometers (IFOs) to evaluate the
direction of an incident gravitational wave burst (GWB). First, we discuss an
angular bias in the least squares timing-based approach that becomes
increasingly relevant for moderate to low signal-to-noise ratios. We show how
estimates of the arrival time uncertainties in each detector can be used to
correct this bias. We also introduce a stand alone parameter estimation
algorithm that can improve the arrival time estimation and provide
root-sum-squared strain amplitude (hrss) values for each site. In the second
part of the paper we discuss how to resolve the directional ambiguity that
arises from observations in three non co-located interferometers between the
true source location and its mirror image across the plane containing the
detectors. We introduce a new, exact relationship among the hrss values at the
three sites that, for sufficiently large signal amplitudes, determines the true
source direction regardless of whether or not the signal is linearly polarized.
Both the algorithm estimating arrival times, arrival time uncertainties, and
hrss values and the directional follow-up can be applied to any set of
gravitational wave candidates observed in a network of three non co-located
interferometers. As a case study we test the methods on simulated waveforms
embedded in simulations of the noise of the LIGO and Virgo detectors at design
sensitivity.Comment: 10 pages, 14 figures, submitted to PR
Exploring the Use of Numerical Relativity Waveforms in Burst Analysis of Precessing Black Hole Mergers
Recent years have witnessed tremendous progress in numerical relativity and
an ever improving performance of ground-based interferometric gravitational
wave detectors. In preparation for Advanced LIGO and a new era in gravitational
wave astronomy, the numerical relativity and gravitational wave data analysis
communities are collaborating to ascertain the most useful role for numerical
relativity waveforms in the detection and characterization of binary black hole
coalescences. In this paper, we explore the detectability of equal mass,
merging black hole binaries with precessing spins and total mass M_T in
[80,350]Msol, using numerical relativity waveforms and template-less search
algorithms designed for gravitational wave bursts. In particular, we present a
systematic study using waveforms produced by the MAYAKRANC code that are added
to colored, Gaussian noise and analyzed with the Omega burst search algorithm.
Detection efficiency is weighed against the orientation of one of the
black-hole's spin axes. We find a strong correlation between the detection
efficiency and the radiated energy and angular momentum, and that the inclusion
of the l=2, m=+/-1,0 modes, at a minimum, is necessary to account for the full
dynamics of precessing systems.Comment: 9 pages, 15 figure
Sensitivity Comparison of Searches for Binary Black Hole Coalescences with Ground-based Gravitational-Wave Detectors
Searches for gravitational-wave transients from binary black hole
coalescences typically rely on one of two approaches: matched filtering with
templates and morphology-independent excess power searches. Multiple
algorithmic implementations in the analysis of data from the first generation
of ground-based gravitational wave interferometers have used different
strategies for the suppression of non-Gaussian noise transients, and targeted
different regions of the binary black hole parameter space. In this paper we
compare the sensitivity of three such algorithms: matched filtering with full
coalescence templates, matched filtering with ringdown templates and a
morphology-independent excess power search. The comparison is performed at a
fixed false alarm rate and relies on Monte-carlo simulations of binary black
hole coalescences for spinning, non-precessing systems with total mass 25-350
solar mass, which covers the parameter space of stellar mass and intermediate
mass black hole binaries. We find that in the mass range of 25 -100 solar mass
the sensitive distance of the search, marginalized over source parameters, is
best with matched filtering to full waveform templates, to within 10 percent at
a false alarm rate of 3 events per year. In the mass range of 100-350 solar
mass, the same comparison favors the morphology-independent excess power search
to within 20 percent. The dependence on mass and spin is also explored.Comment: 11 pages, 2 tables, 25 figure
Gravitational wave burst vetoes in the LIGO S2 and S3 data analyses
The LIGO detectors collected about 4 months of data in 2003-2004 during two
science runs, S2 and S3. Several environmental and auxiliary channels that
monitor the instruments' physical environment and overall interferometric
operation were analyzed in order to establish the quality of the data as well
as the presence of transients of non-astrophysical origin. This analysis
allowed better understanding of the noise character of the instruments and the
establishment of correlations between transients in these channels and the one
recording the gravitational wave strain. In this way vetoes for spurious burst
were identified. We present the methodology we followed in this analysis and
the results from the S2 and S3 veto analysis within the context of the search
for gravitational wave bursts.Comment: 9 pages, 4 figures, submitted to Classical and Quantum Gravity for
the special issue of the GWDAW9 Proceeding
Performance of a Chirplet-based analysis for gravitational waves from binary black hole mergers
The gravitational wave (GW) signature of a binary black hole (BBH)
coalescence is characterized by rapid frequency evolution in the late inspiral
and merger phases. For a system with total mass larger than 100 M_sun, ground
based GW detectors are sensitive to the merger phase, and the in-band whitened
waveform is a short-duration transient lasting about 10-30 ms. For a symmetric
mass system with total mass between 10 and 100 M_sun, the detector is sensitive
instead to the inspiral phase and the in-band signal has a longer duration,
between 30 ms - 3 s. Omega is a search algorithm for GW bursts that, with the
assumption of locally stationary frequency evolution, uses sine-Gaussian
wavelets as a template bank to decompose interferometer strain data. The local
stationarity of sine-Gaussians induces a performance loss for the detection of
lower mass BBH signatures, due to the mismatch between template and signal. We
present the performance of a modified version of the Omega algorithm, Chirplet
Omega, which allows a linear variation of frequency, to target BBH
coalescences. The use of Chirplet-like templates enhances the measured
signal-to-noise ratio due to less mismatch between template and data, and
increases the detectability of lower mass BBH coalescences. We present the
results of a performance study of Chirplet Omega in colored Gaussian noise at
initial LIGO sensitivity.Comment: 7 pages, 12 figures. Proceedings of Amaldi-9, Cardiff (UK), 201
Complete phenomenological gravitational waveforms from spinning coalescing binaries
The quest for gravitational waves from coalescing binaries is customarily
performed by the LIGO-Virgo collaboration via matched filtering, which requires
a detailed knowledge of the signal. Complete analytical coalescence waveforms
are currently available only for the non-precessing binary systems. In this
paper we introduce complete phenomenological waveforms for the dominant
quadrupolar mode of generically spinning systems. These waveforms are
constructed by bridging the gap between the analytically known inspiral phase,
described by spin Taylor (T4) approximants in the restricted waveform
approximation, and the ring-down phase through a phenomenological intermediate
phase, calibrated by comparison with specific, numerically generated waveforms,
describing equal mass systems with dimension-less spin magnitudes equal to 0.6.
The overlap integral between numerical and phenomenological waveforms ranges
between 0.95 and 0.99.Comment: Proceeding for the GWDAW-14 conference. Added reference in v
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