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Oscillating compact stars are promising sources of gravitational radiation. Upper limits on gravitational-wave (GW) burst emission associated with a Vela timing glitch and in coincidence with electromagnetic triggers from magnetars were set recently by the LIGO and Virgo Collaborations. Those searches targeted f-modes of neutron stars with standard equations of state. Indeed, the f-modes are believed to be the principal GW emitters of conventional neutron stars; their high frequencies, though, imply that we would be able to detect only very energetic nearby events. Exotic equations of state, on the other hand, which predict elastic quark matter cores, may be much more interesting. LIGO and Virgo continuous-wave searches are already able to put constraints on the physics of such objects by comparing theoretical models with data analysis...
Comment: 6 pages, 1 figure. Accepted for publication to MNRAS
Time shifting the output of gravitational wave detectors operating in coincidence is a convenient way of estimating the background in a search for short-duration signals. In this paper, we show how non-stationary data affect the background estimation precision. We present a method of measuring the fluctuations of the data and computing its effects on a coincident search. In particular, we show that for fluctuations of moderate amplitude, time slides larger than the fluctuation time scales can be used. We also recall how the false alarm variance saturates with the number of time shifts.
We summarize the sensitivity achieved by the LIGO and Virgo gravitational wave detectors for low-mass compact binary coalescence (CBC) searches during LIGO's sixth science run and Virgo's second and third science runs. We present strain noise power spectral densities (PSDs) which are representative of the typical performance achieved by the detectors in these science runs. The data presented here and in the accompanying web-accessible data files are intended to be released to the public as a summary of detector performance for low-mass CBC searches during S6 and VSR2-3.
The Virgo detector is a kilometer-length interferometer for gravitational wave detection located near Pisa (Italy). During its second science run (VSR2) in 2009, 6 months of data were accumulated with a sensitivity close to its design. In this paper, the methods used to determine the parameters for sensitivity estimation and gravitational wave reconstruction are described. The main quantities to be calibrated are the frequency response of the mirror actuation and the sensing of the output power. Focus is also put on their absolute timing. The monitoring of the calibration data and the parameter estimation with independent techniques are discussed to provide an estimation of the calibration uncertainties. Finally, the estimation of the Virgo sensitivity in the frequency domain is described and typical sensitivities measured during VSR2 ...
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