700 research outputs found
Analysis of noise sources in the Virgo sensitivity
No full textNational audienceIn this paper the analysis techniques used to identify the instrumental noises which limit the sensitivity of the interferometric gravitational waves detector Virgo are presented as well as the present noise budget
The search for gravitational waves in real life
No full textOne of the main challenges faced by GW data-analysis pipelines is to identify rare signals buried in non-Gaussian and non-stationary detector noise. Searches looking for transient signals such as burst or inspiral waveforms are very sensitive to instrumental artifacts and environmental noise, and can therefore be affected by high false alarm rates. Analysis pipelines are designed accordingly to keep the rate of false alarms as low as possible while maintaining thresholds favoring detections. In this lecture I intend to give an overview of the analysis pipeline that has been developed by the LIGO-Virgo Compact Binary Coalescence data-analysis working group. In particular I would like to emphasize the various techniques that have been implemented in the pipeline to minimize the false alarm rate and to discriminate signals from background noise. This includes for instance data quality vetoes and signal-based vetoes, network analysis techniques such as coincidences between detectors, and optimal ranking statistics. Candidates surviving the analysis pipeline are also examined with a detection check-list. An introduction to the software infrastructure that the analysis pipeline relies on will also be given
Searches for gravitational waves from compact binary coalescences with LIGO and Virgo
No full textInternational audienc
Analyse de la sensibilité du détecteur d'ondes gravitationnelles Virgo
No full textThe Virgo detector for gravitational waves is a laser interferometer with arms which are 3 km long. This interferometer is at present in its commissioning phase whose goal is to reach the Virgo nominal sensitivity. To this purpose it is necessary to reduce the technical noises which are limiting the sensitivity during this phase. The work described in this thesis focuses on the analysis of technical noises.The noises which are known to be likely to limit the sensitivity are first described and their propagation mechanism is also explained. The method used to analyse the technical noises is then presented. It first consists in identifying the possible noise sources by looking for coherence between the interferometer signals. Then it is useful to understand how the noise propagates into the interferometer. This is done by building analytical models of propagation. Some studies based on a simulation of the detector have been added to the analysis of interferometer data.Between the end of 2003 and the end of 2005, the advance of the commissioning has been punctuated with seven technical data taking periods, performed in order to check the evolution of the detector performance. The analysis of the noises limiting the interferometer sensitivity for each of these data taking is presented in this thesis. The impact of the technical upgrades implemented on the interferometer to suppress the effect of these noises is also discussed.Le détecteur d'ondes gravitationnelles Virgo est un interféromètre laser dont les bras font trois kilomètres de long. Cet interféromètre est actuellement dans une phase de réglages et d'ajustements ayant pour but d'amener l'instrument à sa sensibilité nominale. Il est pour cela nécessaire de réduire les bruits instrumentaux qui limitent la sensibilité pendant cette phase. Le travail décrit dans ce mémoire est consacré à l'analyse des bruits instrumentaux.Une description des bruits que l'on sait susceptibles de limiter la sensibilité de l'interféromètre est d'abord présentée, ainsi que leur mécanisme de propagation. La méthode ayant permis d'analyser les bruits instrumentaux est ensuite exposée. Elle consiste tout d'abord à identifier les sources de bruit potentielles par la recherche de cohérence entre les signaux de l'interféromètre. Il est ensuite utile de comprendre le mécanisme par lequel ces bruits se propagent dans l'interféromètre en élaborant des modèles analytiques. Cette analyse, appliquée aux données de l'interféromètre, a été complétée par des études utilisant une simulation du détecteur. Entre fin 2003 et fin 2005, les progrès de la mise en route de Virgo ont été ponctués par sept prises de données techniques, qui ont permis de vérifier l'évolution des performances du détecteur. Les résultats de l'analyse des bruits limitant la sensibilité de l'interféromètre au cours de chacune de ces prises de données techniques sont présentés dans ce mémoire. L'impact des améliorations techniques apportées à l'interféromètre pour éliminer l'effet de ces bruits est également discuté
Design of a high-magnification and low-aberration compact catadioptric telescope for the Advanced Virgo gravitational-wave interferometric detector
No full textInternational audienceAdvanced Virgo is a major upgrade of the Virgo gravitational-wave detector, aiming to increase its sensitivity by an order of magnitude. Among the main modifications of the instrument, the size of the laser beam inside the central area has been roughly doubled. Consequently, the input/output optics systems have been re-designed. Due to the overall Advanced Virgo optical scheme, high-magnification and compact telescopes are needed. These telescopes also have to fulfill stringent requirements in terms of aberrations, separation of secondary beams and scattered light. In this paper we describe the design of the Advanced Virgo telescopes and their estimated performances in terms of tuning capability and optical properties
Constraints from LIGO O3 data on gravitational-wave emission due to r-modes in the glitching pulsar PSR J0537-6910
No full textWe present a search for continuous gravitational-wave emission due to r-modes in the pulsar PSR J0537-6910 using data from the LIGO-Virgo Collaboration observing run O3. PSR J0537-6910 is a young energetic X-ray pulsar and is the most frequent glitcher known. The inter-glitch braking index of the pulsar suggests that gravitational-wave emission due to r-mode oscillations may play an important role in the spin evolution of this pulsar. Theoretical models confirm this possibility and predict emission at a level that can be probed by ground-based detectors. In order to explore this scenario, we search for r-mode emission in the epochs between glitches by using a contemporaneous timing ephemeris obtained from NICER data. We do not detect any signals in the theoretically expected band of 86-97 Hz, and report upper limits on the amplitude of the gravitational waves. Our results improve on previous amplitude upper limits from r-modes in J0537-6910 by a factor of up to 3 and place stringent constraints on theoretical models for r-mode driven spin-down in PSR J0537-6910, especially for higher frequencies at which our results reach below the spin-down limit defined by energy conservation
Erratum: All-sky search for gravitational-wave bursts in the first joint LIGO-GEO-Virgo run (Physical Review D - Particles, Fields, Gravitation and Cosmology (2010) 81 (102001))
No full textThis paper was published online on 5 May 2010 with an omission in the Collaboration author list. S. Dwyer has been
added as of 12 April 2012. The Collaboration author list is incorrect in the printed version of the journal
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