132 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
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
Null-stream veto for two co-located detectors: Implementation issues
Time-series data from multiple gravitational wave (GW) detectors can be
linearly combined to form a null-stream, in which all GW information will be
cancelled out. This null-stream can be used to distinguish between actual GW
triggers and spurious noise transients in a search for GW bursts using a
network of detectors. The biggest source of error in the null-stream analysis
comes from the fact that the detector data are not perfectly calibrated. In
this paper, we present an implementation of the null-stream veto in the
simplest network of two co-located detectors. The detectors are assumed to have
calibration uncertainties and correlated noise components. We estimate the
effect of calibration uncertainties in the null-stream veto analysis and
propose a new formulation to overcome this. This new formulation is
demonstrated by doing software injections in Gaussian noise.Comment: Minor changes; To appear in Class. Quantum Grav. (Proc. GWDAW10
Search algorithm for a gravitational wave signal in association with Gamma Ray Burst GRB030329 using the LIGO detectors
One of the brightest Gamma Ray Burst ever recorded, GRB030329, occurred
during the second science run of the LIGO detectors. At that time, both
interferometers at the Hanford, WA LIGO site were in lock and acquiring data.
The data collected from the two Hanford detectors was analyzed for the presence
of a gravitational wave signal associated with this GRB. This paper presents a
detailed description of the search algorithm implemented in the current
analysis.Comment: To appear in the Proceedings of 8th Gravitational Wave Data Analysis
Workshop (Milwaukee, WI) (Class. Quantum Grav.
LOOC UP: Locating and observing optical counterparts to gravitational wave bursts
Gravitational wave (GW) bursts (short duration signals) are expected to be
associated with highly energetic astrophysical processes. With such high
energies present, it is likely these astrophysical events will have signatures
in the EM spectrum as well as in gravitational radiation. We have initiated a
program, "Locating and Observing Optical Counterparts to Unmodeled Pulses in
Gravitational Waves" (LOOC UP) to promptly search for counterparts to GW burst
candidates. The proposed method analyzes near real-time data from the
LIGO-Virgo network, and then uses a telescope network to seek optical-transient
counterparts to candidate GW signals. We carried out a pilot study using
S5/VSR1 data from the LIGO-Virgo network to develop methods and software tools
for such a search. We will present the method, with an emphasis on the
potential for such a search to be carried out during the next science run of
LIGO and Virgo, expected to begin in 2009.Comment: 11 pages, 2 figures; v2) added acknowledgments, additional
references, and minor text changes v3) added 1 figure, additional references,
and minor text changes. v4) Updated references and acknowledgments. To be
published in the GWDAW 12 Conf. Proc. by Classical and Quantum Gravit
Methods for Reducing False Alarms in Searches for Compact Binary Coalescences in LIGO Data
The LIGO detectors are sensitive to a variety of noise transients of
non-astrophysical origin. Instrumental glitches and environmental disturbances
increase the false alarm rate in the searches for gravitational waves. Using
times already identified when the interferometers produced data of questionable
quality, or when the channels that monitor the interferometer indicated
non-stationarity, we have developed techniques to safely and effectively veto
false triggers from the compact binary coalescences (CBCs) search pipeline
Coherent method for detection of gravitational wave bursts
We describe a coherent network algorithm for detection and reconstruction of
gravitational wave bursts. The algorithm works for two and more arbitrarily
aligned detectors and can be used for both all-sky and triggered burst
searches. We describe the main components of the algorithm, including the
time-frequency analysis in wavelet domain, construction of the likelihood
time-frequency maps, the identification and selection of burst events.Comment: 11 pages, 3 figures, proceedings of Amaldi conference in Sydney,
Australi
The LSC Glitch Group : Monitoring Noise Transients during the fifth LIGO Science Run
The LIGO Scientific Collaboration (LSC) glitch group is part of the LIGO
detector characterization effort. It consists of data analysts and detector
experts who, during and after science runs, collaborate for a better
understanding of noise transients in the detectors. Goals of the glitch group
during the fifth LIGO science run (S5) included (1) offline assessment of the
detector data quality, with focus on noise transients, (2) veto recommendations
for astrophysical analysis and (3) feedback to the commissioning team on
anomalies seen in gravitational wave and auxiliary data channels. Other
activities included the study of auto-correlation of triggers from burst
searches, stationarity of the detector noise and veto studies. The group
identified causes for several noise transients that triggered false alarms in
the gravitational wave searches; the times of such transients were identified
and vetoed from the data generating the LSC astrophysical results.Comment: 9 pages, 8 figures, Contribution to 12th Gravitational Wave Data
Analysis Workshop. Changes in response to referee comments. Accepted for
publication in CQ
X-Pipeline: An analysis package for autonomous gravitational-wave burst searches
Autonomous gravitational-wave searches -- fully automated analyses of data
that run without human intervention or assistance -- are desirable for a number
of reasons. They are necessary for the rapid identification of
gravitational-wave burst candidates, which in turn will allow for follow-up
observations by other observatories and the maximum exploitation of their
scientific potential. A fully automated analysis would also circumvent the
traditional "by hand" setup and tuning of burst searches that is both
labourious and time consuming. We demonstrate a fully automated search with
X-Pipeline, a software package for the coherent analysis of data from networks
of interferometers for detecting bursts associated with GRBs and other
astrophysical triggers. We discuss the methods X-Pipeline uses for automated
running, including background estimation, efficiency studies, unbiased optimal
tuning of search thresholds, and prediction of upper limits. These are all done
automatically via Monte Carlo with multiple independent data samples, and
without requiring human intervention. As a demonstration of the power of this
approach, we apply X-Pipeline to LIGO data to search for gravitational-wave
emission associated with GRB 031108. We find that X-Pipeline is sensitive to
signals approximately a factor of 2 weaker in amplitude than those detectable
by the cross-correlation technique used in LIGO searches to date. We conclude
with the prospects for running X-Pipeline as a fully autonomous, near real-time
triggered burst search in the next LSC-Virgo Science Run.Comment: 18 pages, 10 figures. Minor edits and clarifications; added more
background on gravitational waves and detectors. To appear in New Journal of
Physics
The ligo gravitational wave observatories: Recent results and future plans
The LIGO interferometers are operating as gravitational wave observatories, with a noise level near an order of magnitude of the goal and the first scientific data recently taken. This data has been analyzed for four different categories of gravitational wave sources; millisecond bursts, inspiralling binary neutron stars, periodic waves from a known pulsar, and stochastic background. Research and development is also underway for the next generation LIGO detector, Advanced LIGO
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