186 research outputs found
A Cross-correlation method to search for gravitational wave bursts with AURIGA and Virgo
We present a method to search for transient GWs using a network of detectors
with different spectral and directional sensitivities: the interferometer Virgo
and the bar detector AURIGA. The data analysis method is based on the
measurements of the correlated energy in the network by means of a weighted
cross-correlation. To limit the computational load, this coherent analysis step
is performed around time-frequency coincident triggers selected by an excess
power event trigger generator tuned at low thresholds. The final selection of
GW candidates is performed by a combined cut on the correlated energy and on
the significance as measured by the event trigger generator. The method has
been tested on one day of data of AURIGA and Virgo during September 2005. The
outcomes are compared to the results of a stand-alone time-frequency
coincidence search. We discuss the advantages and the limits of this approach,
in view of a possible future joint search between AURIGA and one
interferometric detector.Comment: 11 pages, 6 figures, submitted to CQG special issue for Amaldi 7
Proceeding
The variable finesse locking technique
Virgo is a power recycled Michelson interferometer, with 3 km long Fabry-Perot cavities in the arms. The locking of the interferometer has been obtained with an original lock acquisition technique. The main idea is to lock the instrument away from its working point. Lock is obtained by misaligning the power recycling mirror and detuning the Michelson from the dark fringe. In this way, a good fraction of light escapes through the antisymmetric port and the power build-up inside the recycling cavity is extremely low. The benefit is that all the degrees of freedom are controlled when they are almost decoupled, and the linewidth of the recycling cavity is large. The interferometer is then adiabatically brought on to the dark fringe. This technique is referred to as variable finesse, since the recycling cavity is considered as a variable finesse Fabry-Perot. This technique has been widely tested and allows us to reach the dark fringe in few minutes, in an essentially deterministic way
Astrophysically Triggered Searches for Gravitational Waves: Status and Prospects
In gravitational-wave detection, special emphasis is put onto searches that
focus on cosmic events detected by other types of astrophysical observatories.
The astrophysical triggers, e.g. from gamma-ray and X-ray satellites, optical
telescopes and neutrino observatories, provide a trigger time for analyzing
gravitational wave data coincident with the event. In certain cases the
expected frequency range, source energetics, directional and progenitor
information is also available. Beyond allowing the recognition of gravitational
waveforms with amplitudes closer to the noise floor of the detector, these
triggered searches should also lead to rich science results even before the
onset of Advanced LIGO. In this paper we provide a broad review of LIGO's
astrophysically triggered searches and the sources they target
Length Sensing and Control in the Virgo Gravitational Wave Interferometer
The gravitational wave detector Virgo is presently being commissioned. A significant part of last year was spent in setting up the cavity length control system. This work was carried out with steps of increasing complexity: locking a simple Fabry-Perot cavity, then a Michelson interferometer with Fabry-Perot cavities in both arms, and finally recycling the light beam into the interferometer. The applied strategy and the main results obtained are describe
Status of coalescing binaries search activities in Virgo
The interferometric gravitational wave detector Virgo is undergoing an advanced phase of its commissioning, during which short runs are routinely performed, in which data are analyzed online and offline, searching for signals from coalescing binary systems. In this report we present the progress of the coalescing binaries search activities in Virgo, and we describe details of the detection pipeline including hardware injections, vetoes, and parameter estimation, using recent data taking
Interferometric detectors of gravitational waves on Earth: the next generations
International audienceThe interferometric detectors of gravitational waves of first generation are now taking data. A first detection might be possible with these instruments, but more sensitive detectors will be needed to start the gravitational wave astronomy. The interferometers of second generation will improve the sensitivity by a factor ten, allowing to explore a universe volume 1000 times larger. The technology is almost ready and the construction will start at the beginning of next decade. The community of the physicists involved in the field has also started to make plans for third generation detectors, for which a long term technology development will be required. The plans for the upgrades of the existing detectors and the scenario for the evolution of the field will be reviewed in this paper
LIGO and VIRGO: large interferometers searching for gravitational waves
International audienceThe largest interferometric detectors for gravitational waves, LIGO and Virgo, have reached (or are close to) the design sensitivity and have started taking science data. The operation of such detectors is reviewed and the expected sources and detection rates are discussed. LIGO and Virgo might make the first detection, but more advanced detectors will be needed to truly open the field of gravitational wave astronomy: the current ideas and plans for the upgrades of the existing interferometers are presented
Noise budget and noise hunting in VIRGO
International audienc
Data Acquisition System of the Virgo Gravitational Waves Interferometric Detector
International audienceVirgo is an experiment aiming at the detection of gravitational waves emitted by astrophysical sources. Its detector, based on a 3km arms interferometer, is a complex setup which requires several digital control loops running up to 10kHz, an accurate and reliable central timing system and an efficient data acquisition, all of them being distributed over 3km. We overview here the main hardware and software components developed for the data acquisition system (DAQ) and its current architecture. Then, we briefly discuss its connections with interferometer's controls, especially through the automation of the interferometer's startup procedure. Then, we describe the tools used to monitor the DAQ and the performances we measured with them. Finally, are described also the tools developped for the online detector monitoring, mandatory complement of the DAQ for the commissioning of the Virgo detector
The status of VIRGO
In this paper the main characteristics of the interferometric gravitational waves detector Virgo are presented as well as its present status and perspectives
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