1,721,780 research outputs found
Erratum: Tests of General Relativity with GW150914 [Phys. Rev. Lett. 116, 221101 (2016)]
Full text linkThis Erratum reports an error found in the implementation of the code of the LIGO Scientific and Virgo Collaborations (LVC) as used in gravitational-wave-based estimations of possible deviations from the post-Newtonian (PN) terms expected in general relativity (GR). The error concerned the 0.5 PN term and affected the results previously published for GW150914 [1] in Ref. [2], for GW151226 [3] in Ref. [4], and for GW170104 in Ref. [5]. We corrected the bug and present the reproduced results in this Erratum, as well as in the related Errata [6,7]. The main conclusion, that the results are consistent with general relativity, remains. In Ref. [2], the test for the parameterized post-Newtonian [8] deviations from the expected GR values relied on creating non-GR waveforms [9-13] and using them as potential matches for the observed waveforms [14-17]. In these waveforms, implemented in the frequency domain, freedom was introduced by allowing the phase coefficients describing different powers of the post-Newtonian parameter (equivalently, powers of the frequency) to assume a range of values, not only the particular values prescribed by GR. However, a coding bug was introduced, identically zeroing the deviations at 0.5 PN in the inspiral regime (as in GR). The 0.5 PN deviations were hence absent in the phasing formula, though not in the junction conditions that relate the inspiral regime to the intermediate regime. Any constraints obtained in [2,4,5] only resulted from the latter. This error affected the results of the non-GR parameter estimation (PE) [14] pipeline tests performed for finding bounds on possible PN deviations from GR. In particular, they affect the bounds on the single deviations in the 0.5 PN term and on the tests with multiple deviations together. These erroneous results appeared in Figs. 6 and 7 and Table I of [2], in Figs. 7 and 8 of [4], and in Fig. 9 of the Supplemental Material of [5]. The corrected versions of all of these have been produced. The corrections for Figs. 6 and 7 and Table I of [2] appear below, while the others are available in [6,7]. All these results are consistent with GR. (Figure Presented). The error, introduced by erroneous caching during the optimization of the waveform generation for efficient PE, has been corrected in commit [18] of the lalsuite [19] code. No subsequent LVC papers have been affected. Note that, while this error also affected the analysis of GW170608 [20], the reported results require no changes: with the corrected analysis, the GR-predicted PN coefficient values continue to be consistent with the data. No change is required regarding the preliminary reported results for GW170814 [21] either
The inertial damping of the VIRGO superattenuator and the residual motion of the mirror
No full textThe VIRGO superattenuator (SA) is effective in suppressing seismic noise below the expected thermal noise level above 4 Hz. However, the residual mirror motion associated with the SA normal modes can saturate the interferometer control system. This motion is reduced by implementing a wideband (DC-5 Hz) multidimensional active control (the so-called inertial damping) which makes use of both accelerometers and position sensors and of a digital signal processing (DSP) system. Feedback forces are exerted by coil-magnet actuators on the top of an inverted pendulum pre-isolator stage. The residual root mean square motion of the mirror in 10 s is less than 0.1 mum
Multimessenger search for sources of gravitational waves and high-energy neutrinos: Initial results for LIGO-Virgo and IceCube
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Search for transient gravitational waves in coincidence with short-duration radio transients during 2007-2013
No full textWe present an archival search for transient gravitational-wave bursts in coincidence with 27 single-pulse
triggers from Green Bank Telescope pulsar surveys, using the LIGO, Virgo, and GEO interferometer
network.We also discuss a check for gravitational-wave signals in coincidence with Parkes fast radio bursts
using similar methods. Data analyzed in these searches were collected between 2007 and 2013. Possible
sources of emission of both short-duration radio signals and transient gravitational-wave emission include
starquakes on neutron stars, binary coalescence of neutron stars, and cosmic string cusps. While no evidence
for gravitational-wave emission in coincidence with these radio transients was found, the current analysis
serves as a prototype for similar future searches using more sensitive second-generation interferometers
The NINJA-2 project: detecting and characterizing gravitational waveforms modelled using numerical binary black hole simulations
No full textImplementation of an F-statistic all-sky search for continuous gravitational waves in Virgo VSR1 data
No full textImproved Upper Limits on the Stochastic Gravitational-Wave Background from 2009-2010 LIGO and Virgo Data
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