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The gravitational-wave (GW) sky may include nearby pointlike sources as well as stochastic backgrounds. We perform two directional searches for persistent GWs using data from the LIGO S5 science run: one optimized for pointlike sources and one for arbitrary extended sources. Finding no evidence to support the detection of GWs, we present 90% confidence(More)
Aims. A transient astrophysical event observed in both gravitational wave (GW) and electromagnetic (EM) channels would yield rich scientific rewards. A first program initiating EM follow-ups to possible transient GW events has been developed and exercised by the LIGO and Virgo community in association with several partners. In this paper, we describe and(More)
Gravitational waves from a variety of sources are predicted to superpose to create a stochastic background. This background is expected to contain unique information from throughout the history of the Universe that is unavailable through standard electromagnetic observations, making its study of fundamental importance to understanding the evolution of the(More)
A stochastic background of gravitational waves is expected to arise from a superposition of a large number of unresolved gravitational-wave sources of astrophysical and cosmological origin. It should carry unique signatures from the earliest epochs in the evolution of the Universe, inaccessible to standard astrophysical observations. Direct measurements of(More)
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 FabryPerot cavity, then a Michelson interferometer with Fabry-Perot cavities in both arms, and finally recycling the(More)
We describe a model evaluating changes in the optical isolation of a Faraday isolator when passing from air to vacuum in terms of different thermal effects in the crystal. The changes are particularly significant in the crystal thermal lensing (refraction index and thermal expansion) and in its Verdet constant and can be ascribed to the less efficient(More)
As they take data and improve their sensitivities, interferometric gravitational wave detectors will eventually detect signals emitted by inspiralling compact binary systems. Determining the sky position of the source will require that the signal be recorded in several detectors. The precision of the source direction determination will be driven by that of(More)
In this paper, we describe the analysis performed in the data of C6 and C7 commissioning runs of Virgo for the search of periodic sources of gravitational waves. The analysis is all-sky, covers the frequency range between 50 Hz and 1050 Hz and neutron star spin-down rate below 1.58 × 10−8 Hz s−1. Coincidences in the source parameter space between candidates(More)
  • F Acerneseac, M Alshourbagyab, +141 authors M. Yvert
  • 2008
In the framework of the expected association between gamma-ray bursts and gravitational waves, we present results of an analysis aimed to search for a burst of gravitational waves in coincidence with gamma-ray burst 050915a. This was a long duration gamma-ray burst detected by Swift during September 2005, when the Virgo gravitational wave detector was(More)