797 research outputs found
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
Parameter Estimation for Gravitational-wave Bursts with the BayesWave Pipeline
We provide a comprehensive multi-aspect study of the performance of a pipeline used by the LIGO-Virgo Collaboration for estimating parameters of gravitational-wave bursts. We add simulated signals with four different morphologies (sine-Gaussians (SGs), Gaussians, white-noise bursts, and binary black hole signals) to simulated noise samples representing noise of the two Advanced LIGO detectors during their first observing run. We recover them with the BayesWave (BW) pipeline to study its accuracy in sky localization, waveform reconstruction, and estimation of model-independent waveform parameters. BW localizes sources with a level of accuracy comparable for all four morphologies, with the median separation of actual and estimated sky locations ranging from 25 degrees. 1 to 30 degrees. 3. This is a reasonable accuracy in the two-detector case, and is comparable to accuracies of other localization methods studied previously. As BW reconstructs generic transient signals with SG wavelets, it is unsurprising that BW performs best in reconstructing SG and Gaussian waveforms. The BW accuracy in waveform reconstruction increases steeply with the network signal-to-noise ratio (S/N-net), reaching a 85% and 95% match between the reconstructed and actual waveform below S/N-net approximate to 20 and S/N-net approximate to 50, respectively, for all morphologies. The BW accuracy in estimating central moments of waveforms is only limited by statistical errors in the frequency domain, and is also affected by systematic errors in the time domain as BW cannot reconstruct low-amplitude parts of signals that are overwhelmed by noise. The figures of merit we introduce can be used in future characterizations of parameter estimation pipelines
A First Comparison Between LIGO and Virgo Inspiral Search Pipelines
This article reports on a project that is the first step the LIGO Scientific
Collaboration and the Virgo Collaboration have taken to prepare for the mutual
search for inspiral signals. The project involved comparing the analysis
pipelines of the two collaborations on data sets prepared by both sides,
containing simulated noise and injected events. The ability of the pipelines to
detect the injected events was checked, and a first comparison of how the
parameters of the events were recovered has been completed.Comment: GWDAW-9 proceeding
A first comparison of search methods for gravitational wave bursts using LIGO and Virgo simulated data
We present a comparative study of 6 search methods for gravitational wave
bursts using simulated LIGO and Virgo noise data. The data's spectra were
chosen to follow the design sensitivity of the two 4km LIGO interferometers and
the 3km Virgo interferometer. The searches were applied on replicas of the data
sets to which 8 different signals were injected. Three figures of merit were
employed in this analysis: (a) Receiver Operator Characteristic curves, (b)
necessary signal to noise ratios for the searches to achieve 50 percent and 90
percent efficiencies, and (c) variance and bias for the estimation of the
arrival time of a gravitational wave burst.Comment: GWDAW9 proceeding
Plans for the LIGO-TAMA Joint Search for Gravitational Wave Bursts
We describe the plans for a joint search for unmodelled gravitational wave
bursts being carried out by the LIGO and TAMA collaborations using data
collected during February-April 2003. We take a conservative approach to
detection, requiring candidate gravitational wave bursts to be seen in
coincidence by all four interferometers. We focus on some of the complications
of performing this coincidence analysis, in particular the effects of the
different alignments and noise spectra of the interferometers.Comment: Proceedings of the 8th Gravitational Wave Data Analysis Workshop,
Milwaukee, WI, USA. 10 pages, 3 figures, documentclass ``iopart'
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
A combined analysis technique for the search for fast magnetic monopoles with the MACRO detector
We describe a search method for fast moving ()
magnetic monopoles using simultaneously the scintillator, streamer tube and
track-etch subdetectors of the MACRO apparatus. The first two subdetectors are
used primarily for the identification of candidates while the track-etch one is
used as the final tool for their rejection or confirmation. Using this
technique, a first sample of more than two years of data has been analyzed
without any evidence of a magnetic monopole. We set a 90% CL upper limit to the
local monopole flux of in the
velocity range and for nucleon decay
catalysis cross section smaller than .Comment: 29 pages (12 figures). Accepted by Astroparticle Physic
A comparison of methods for gravitational wave burst searches from LIGO and Virgo
The search procedure for burst gravitational waves has been studied using 24
hours of simulated data in a network of three interferometers (Hanford 4-km,
Livingston 4-km and Virgo 3-km are the example interferometers). Several
methods to detect burst events developed in the LIGO Scientific Collaboration
(LSC) and Virgo collaboration have been studied and compared. We have performed
coincidence analysis of the triggers obtained in the different interferometers
with and without simulated signals added to the data. The benefits of having
multiple interferometers of similar sensitivity are demonstrated by comparing
the detection performance of the joint coincidence analysis with LSC and Virgo
only burst searches. Adding Virgo to the LIGO detector network can increase by
50% the detection efficiency for this search. Another advantage of a joint
LIGO-Virgo network is the ability to reconstruct the source sky position. The
reconstruction accuracy depends on the timing measurement accuracy of the
events in each interferometer, and is displayed in this paper with a fixed
source position example.Comment: LIGO-Virgo working group submitted to PR
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