1,721,016 research outputs found
Methods to filter out spurious disturbances in continuous-wave searches from gravitational-wave detectors
No full textSearching for continuous gravitational wave signals using LIGO and Virgo detectors
Full text linkDirect and unequivocal detection of gravitational waves represents a great challenge of contemporary physics and astrophysics. A worldwide effort is currently operating towards this direction, building ever sensitive detectors, improving the modelling of gravitational wave sources and employing ever more sophisticated and powerful data analysis techniques. In this paper we review the current status of LIGO and Virgo ground based interferometric detectors and some data analysis tools used in the continuous wave searches to extract the faint gravitational signals from the interferometric noise data. Moreover we discuss also relevant results from recent continuous wave searches
Coupled harmonic oscillators for the measurement of a weak classical force at the standard quantum limit
No full textDirected searches for continuous gravitational waves from binary systems: Parameter-space metrics and optimal Scorpius X-1 sensitivity
Full text linkWe derive simple analytic expressions for the (coherent and semi-coherent) phase metrics of continuous-wave sources in low-eccentricity binary systems, both for the long-segment and short- segment regimes (compared to the orbital period). The resulting expressions correct and extend previous results found in the literature. We present results of extensive Monte-Carlo studies comparing metric mismatch predictions against the measured loss of detection statistic for binary parameter offsets. The agreement is generally found to be within ~ 10%-30%. As an application of the metric template expressions, we estimate the optimal achievable sensitivity of an Einstein@Home directed search for Scorpius X-1, under the assumption of sufficiently small spin wandering. We find that such a search, using data from the upcoming advanced detectors, would be able to beat the torque- balance level [1,2] up to a frequency of ~ 500 - 600 Hz, if orbital eccentricity is well-constrained, and up to a frequency of ~ 160 - 200 Hz for more conservative assumptions about the uncertainty on orbital eccentricity
New prospects for continuous gravitational wave detection from binary systems in the advanced detector era
Full text linkGravitational wave detection is eagerly expected as one of the major discoveries of the next decade. A worldwide effort is currently underway, building ever-more-sensitive detectors and developing more powerful data-analysis tools. Continuous gravitational waves (CWs) are a promising class of signals for advanced detectors, and a particularly interesting type of CW sources are neutron stars in low-mass X-ray binaries, with Scorpius X-1 being the most remarkable representative. We describe the details of a project aimed to perform directed searches for CWs from binary systems. We use a search algorithm based on coherently computing a maximum likelihood statistic for a bank of signal templates, and then incoherently summing this statistic over the segments in which the entire data set has been previously split. The current strategy strongly relies on the derivation of precise analytic expressions for the (coherent and semicoherent) phase metrics of CW sources in low-eccentricity binary systems, for the two regimes of long and short segments compared to the orbital period. As an application of the metric template expressions, we estimate the optimal achievable sensitivity of an Einstein@Home directed search for Scorpius X-1, under the assumption of sufficiently small spin wandering, and using data from the upcoming advanced detectors. We find that such a search would be able to beat the torque-balance level up to a frequency of 500-600 Hz, if orbital eccentricity is well-constrained, and up to a frequency of ∼160-200 Hz for more conservative assumptions about the uncertainty on orbital eccentricity
Fully coherent follow-up of continuous gravitational-wave candidates: An application to Einstein@Home results
Full text linkWe characterize and present the details of the follow-up method used on the most significant outliers of the Hough Einstein@Home all-sky search for continuous gravitational waves [J. Aasi et al Phys. Rev. D 87, 042001 (2013)]. This follow-up method is based on the two-stage approach introduced by [M. Shaltev and R. Prix, Phys. Rev. D 87, 084057 (2013)], consisting of a semicoherent refinement followed by a fully coherent zoom. We quantify the efficiency of the follow-up pipeline using simulated signals in Gaussian noise. This pipeline does not search beyond first-order frequency spin-down, and therefore we also evaluate its robustness against second-order spin-down. We present the details of the Hough Einstein@Home follow-up [J. Aasi et al Phys. Rev. D 87, 042001 (2013)] on three hardware-injected signals and on the eight most significant search outliers of unknown origin
Antenna pattern of DUAL detectors of gravitational waves and its exploitation in a network of advanced interferometers
Full text linkWe investigate the directional sensitivity to plane gravitational waves (GWs) of DUAL detectors of cylindrical shape. Calculations make use of the finite element method to simulate the responses to the GW Riemann tensor of a single-mass DUAL (SMD) and of a tapered cylinder (TC) in their wide sensitivity bandwidth. We show that one SMD or a pair of TCs is able to cover both GW polarization amplitudes from almost all incoming directions. We discuss the achievable enhancement in tackling the inverse problem for high frequency [~(2–5) kHz] GWs by adding a TC detector to the future advanced LIGO–VIRGO network
Using a cleaning technique for the search of continuous gravitational waves in LIGO data
Full text linkHigh frequency short events, due for instance to delta-like spurious disturbances, may affect the broad band noise level and thus produce a loss in the efficiency of detection of continuous gravitational waves. We identify such events, remove them from a set of LIGO fifth science run (S5) data and characterize the resulting sensitivity improvements. We use the same parameter values as used in a previous pilot study on Virgo data, but do not observe on LIGO S5 data the same sensitivity improvements
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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