1,239 research outputs found
Coincidence Experiments between Interferometric and Resonant Bar Detectors
Gravitational wave coincidence experiments between bars and interferometers may be an attractive option once the new generation of full scale interferometers begins taking data. We discuss various ways in which these disparate types of data can be compared in searches for bursts (from supernovae, for example), for pulsar signals, and for a stochastic background. Comparison of broadband interferometer data with narrowband bar data is appropriate in most searches for bursts, but in many cases the results---especially null results (upper limits)---are difficult to interpret. By narrowbanding the interferometer data to the bandwidth of the bar detector, one produces data sets that may give much clearer information in certain burst searches and that are appropriate for searches for a stochastic background of gravitational waves. We suggest, in fact, that there are circumstances where searches for a stochastic background could be more efficiently performed between a bar and an interferometer than between two interferometers. We examine, in some detail, the effect of narrowbanding the interferometer data. We apply this method to a real interferometer and bar data and assess its signal-to-noise performance for different classes of gravitational wave signals
Data analysis of gravitational-wave signals from spinning neutron stars. IV. An all-sky search
We develop a set of data analysis tools for a realistic all-sky search for
continuous gravitational-wave signals. The methods that we present apply to
data from both the resonant bar detectors that are currently in operation and
the laser interferometric detectors that are in the final stages of
construction and commissioning. We show that with our techniques we shall be
able to perform an all-sky 2-day long coherent search of the narrow-band data
from the resonant bar EXPLORER with no loss of signals with the dimensionless
amplitude greater than .Comment: REVTeX, 26 pages, 1 figure, submitted to Phys. Rev.
Vibrational excitation induced by electron beam and cosmic rays in normal and superconductive aluminum bars
We report new measurements of the acoustic excitation of an Al5056
superconductive bar when hit by an electron beam, in a previously unexplored
temperature range, down to 0.35 K. These data, analyzed together with previous
results of the RAP experiment obtained for T > 0.54 K, show a vibrational
response enhanced by a factor 4.9 with respect to that measured in the normal
state. This enhancement explains the anomalous large signals due to cosmic rays
previously detected in the NAUTILUS gravitational wave detector.Comment: 28 pages, 13 figure
Chi-square test on candidate events from CW signal coherent searches
In a blind search for continuous gravitational wave signals scanning a wide
frequency band one looks for candidate events with significantly large values
of the detection statistic. Unfortunately, a noise line in the data may also
produce a moderately large detection statistic.
In this paper, we describe how we can distinguish between noise line events
and actual continuous wave (CW) signals, based on the shape of the detection
statistic as a function of the signal's frequency. We will analyze the case of
a particular detection statistic, the F statistic, proposed by Jaranowski,
Krolak, and Schutz.
We will show that for a broad-band 10 hour search, with a false dismissal
rate smaller than 1e-6, our method rejects about 70 % of the large candidate
events found in a typical data set from the second science run of the Hanford
LIGO interferometer.Comment: proceedings of GWDAW8, 2003 conference, 12pages, 6 figure
Progress on stochastic background search codes for LIGO
One of the types of signals for which the LIGO interferometric gravitational
wave detectors will search is a stochastic background of gravitational
radiation. We review the technique of searching for a background using the
optimally-filtered cross-correlation statistic, and describe the state of plans
to perform such cross-correlations between the two LIGO interferometers as well
as between LIGO and other gravitational-wave detectors, in particular the
preparation of software to perform such data analysis.Comment: 7 pages, 1 encapsulated PostScript figure, uses IOP class files,
submitted to the proceedings of the 4th Amaldi meeting (which will be
published in Classical and Quantum Gravity
Stochastic Background Search Correlating ALLEGRO with LIGO Engineering Data
We describe the role of correlation measurements between the LIGO
interferometer in Livingston, LA, and the ALLEGRO resonant bar detector in
Baton Rouge, LA, in searches for a stochastic background of gravitational
waves. Such measurements provide a valuable complement to correlations between
interferometers at the two LIGO sites, since they are sensitive in a different,
higher, frequency band. Additionally, the variable orientation of the ALLEGRO
detector provides a means to distinguish gravitational wave correlations from
correlated environmental noise. We describe the analysis underway to set a
limit on the strength of a stochastic background at frequencies near 900 Hz
using ALLEGRO data and data from LIGO's E7 Engineering Run.Comment: 8 pages, 2 encapsulated PostScript figures, uses IOP class files,
submitted to the proceedings of the 7th Gravitational Wave Data Analysis
Workshop (which will be published in Classical and Quantum Gravity
Particle acoustic detection in gravitational wave aluminum resonant antennas
The results on cosmic rays detected by the gravitational antenna NAUTILUS
have motivated an experiment (RAP) based on a suspended cylindrical bar, which
is made of the same aluminum alloy as NAUTILUS and is exposed to a high energy
electron beam. Mechanical vibrations originate from the local thermal expansion
caused by warming up due to the energy lost by particles crossing the material.
The aim of the experiment is to measure the amplitude of the fundamental
longitudinal vibration at different temperatures. We report on the results
obtained down to a temperature of about 4 K, which agree at the level of about
10% with the predictions of the model describing the underlying physical
process.Comment: RAP experiment, 16 pages, 7 figure
Aperture synthesis for gravitational-wave data analysis: Deterministic Sources
Gravitational wave detectors now under construction are sensitive to the
phase of the incident gravitational waves. Correspondingly, the signals from
the different detectors can be combined, in the analysis, to simulate a single
detector of greater amplitude and directional sensitivity: in short, aperture
synthesis. Here we consider the problem of aperture synthesis in the special
case of a search for a source whose waveform is known in detail: \textit{e.g.,}
compact binary inspiral. We derive the likelihood function for joint output of
several detectors as a function of the parameters that describe the signal and
find the optimal matched filter for the detection of the known signal. Our
results allow for the presence of noise that is correlated between the several
detectors. While their derivation is specialized to the case of Gaussian noise
we show that the results obtained are, in fact, appropriate in a well-defined,
information-theoretic sense even when the noise is non-Gaussian in character.
The analysis described here stands in distinction to ``coincidence
analyses'', wherein the data from each of several detectors is studied in
isolation to produce a list of candidate events, which are then compared to
search for coincidences that might indicate common origin in a gravitational
wave signal. We compare these two analyses --- optimal filtering and
coincidence --- in a series of numerical examples, showing that the optimal
filtering analysis always yields a greater detection efficiency for given false
alarm rate, even when the detector noise is strongly non-Gaussian.Comment: 39 pages, 4 figures, submitted to Phys. Rev.
First upper limit analysis and results from LIGO science data: stochastic background
I describe analysis of correlations in the outputs of the three LIGO
interferometers from LIGO's first science run, held over 17 days in August and
September of 2002, and the resulting upper limit set on a stochastic background
of gravitational waves. By searching for cross-correlations between the LIGO
detectors in Livingston, LA and Hanford, WA, we are able to set a 90%
confidence level upper limit of h_{100}^2 Omega_0 < 23 +/- 4.6.Comment: 7 pages; 1 eps figures; proceeding from 2003 Edoardo Amaldi Meeting
on Gravitational Wave
Observational Limit on Gravitational Waves from Binary Neutron Stars in the Galaxy
Using optimal matched filtering, we search 25 hours of data from the LIGO
40-meter prototype laser interferometric gravitational-wave detector for
gravitational-wave chirps emitted by coalescing binary systems within our
Galaxy. This is the first test of this filtering technique on real
interferometric data. An upper limit on the rate R of neutron star binary
inspirals in our Galaxy is obtained: with 90% confidence, R< 0.5/hour. Similar
experiments with LIGO interferometers will provide constraints on the
population of tight binary neutron star systems in the Universe.Comment: RevTeX, minor revisions, exactly as published in PRL 83 (1999) p1498,
4 pages, 2 figures include
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