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2008, Physical Review D
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2012, Journal of Physics: Conference Series
2010
2005, Physical Review D
2008, The Astrophysical Journal
We analyzed the available LIGO data coincident with GRB 070201, a short-duration, hard-spectrum γ-ray burst (GRB) whose electromagnetically determined sky position is coincident with the spiral arms of the Andromeda galaxy (M31). Possible progenitors of such short, hard GRBs include mergers of neutron stars or a neutron star and a black hole, or soft γ-ray repeater (SGR) flares. These events can be accompanied by gravitational-wave emission. No plausible gravitational-wave candidates were found ...
2010, The Astrophysical Journal
Gamma-ray bursts (GRBs) are intense flashes of γ-rays which occur approximately once per day and are isotropically distributed over the sky (see, eg, Mészáros 2006, and references therein). The variability of the bursts on timescales as short as a millisecond indicates that the sources are very compact, while the identification of host galaxies and the measurement of redshifts for more than 100 bursts have shown that GRBs are of extragalactic origin.
2008, Classical and Quantum Gravity
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 engaged in a commissioning run during which the best sensitivity attained in 2005 was exhibited. This offered the opportunity for Virgo's first search for a gravitational wave signal in coincidence with a gamma-ray burst. The result of our study is a set of strain amplitude upper-limits, based on the loudest event approach, for different but quite general types of burst signal waveforms. The best upper-limit strain amplitudes we obtain are h_{rss}=O(10^{-20})Hz^{-1/2} around 200-1500 Hz. These upper-limits allow us to evaluate the level up to which Virgo, when reaching nominal sensitivity, will be able to constrain the gravitational wave output associated with a long burst. Moreover, the analysis here presented plays the role of a prototype, crucial in defining a methodology for gamma-ray burst triggered searches with Virgo and opening the way for future joint analyses with LIGO.
Autonomous gravitational-wave searches -- fully automated analyses of data that run without human intervention or assistance -- are desirable for a number of reasons. They are necessary for the rapid identification of gravitational-wave burst candidates, which in turn will allow for follow-up observations by other observatories and the maximum exploitation of their scientific potential. A fully automated analysis would also circumvent the traditional "by hand" setup and tuning of burst searches that is both labourious and time consuming. We demonstrate a fully automated search with X-Pipeline, a software package for the coherent analysis of data from networks of interferometers for detecting bursts associated with GRBs and other astrophysical triggers. We discuss the methods X-Pipeline uses for automated running, including background estimation, efficiency studies, unbiased optimal tuning of search thresholds, and prediction of upper limits. These are all done automatically via Monte Carlo with multiple independent data samples, and without requiring human intervention. As a demonstration of the power of this approach, we apply X-Pipeline to LIGO data to search for gravitational-wave emission associated with GRB 031108. We find that X-Pipeline is sensitive to signals approximately a factor of 2 weaker in amplitude than those detectable by the cross-correlation technique used in LIGO searches to date. We conclude with the prospects for running X-Pipeline as a fully autonomous, near real-time triggered burst search in the next LSC-Virgo Science Run.
2014, Physical Review D
2005, Physical Review D
2013, Journal of Cosmology and Astroparticle Physics
2005, Physical Review D
2009, Reports on Progress in Physics
The goal of the Laser Interferometric Gravitational-Wave Observatory (LIGO) is to detect and study gravitational waves of astrophysical origin. Direct detection of gravitational waves holds the promise of testing general relativity in the strong-field regime, of providing a new probe of exotic objects such as black hole and neutron stars, and of uncovering unanticipated new astrophysics. LIGO, a joint Caltech-MIT project supported by the National Science Foundation, operates three multi-kilometer interferometers at two widely separated sites in the United States. These detectors are the result of decades of worldwide technology development, design, construction, and commissioning. They are now operating at their design sensitivity, and are sensitive to gravitational wave strains smaller than 1 part in 1E21. With this unprecedented sensitivity, the data are being analyzed to detect or place limits on gravitational waves from a variety of potential astrophysical sources.
2011, The Astrophysical Journal Letters
Magnetars are isolated neutron stars (NSs) powered by extreme magnetic fields (∼ 1015 G; Duncan & Thompson 1992). The magnetar model explains the observed properties of two classes of rare objects, the soft gamma repeaters (SGRs) and the anomalous X-ray pulsars (AXPs): compact X-ray sources with long rotation periods and rapid spindowns which sporadically emit short (≈ 0. 1 s) bursts of soft gamma rays (for a review see Mereghetti 2008). Fewer than 20 SGRs and AXPs are known. The total isotropic burst energies rarely ...
2006, Classical and Quantum Gravity
2011
Results. For signals near the detection threshold, our low-latency algorithms often localized simulated GW burst signals to tens of square degrees, while neutron star/neutron star inspirals and neutron star/black hole inspirals were localized to a few hundred square degrees. Localization precision improves for moderately stronger signals. The correct sky location of signals well above threshold and originating from nearby galaxies may be observed with ~50% or better probability with a few pointings of wide-field telescopes.
2014
2008, Classical and Quantum Gravity
2007, Physical Review D
We have searched for Gravitational Waves (GWs) associated with the SGR 1806-20 hyperflare of 27 December 2004. This event, originating from a Galactic neutron star, displayed exceptional energetics. Recent investigations of the X-ray light curve's pulsating tail revealed the presence of Quasi-Periodic Oscillations (QPOs) in the 30 - 2000 Hz frequency range, most of which coincides with the bandwidth of the LIGO detectors. These QPOs, with well-characterized frequencies, can plausibly be attributed to seismic modes of the neutron star which could emit GWs. Our search targeted potential quasi-monochromatic GWs lasting for tens of seconds and emitted at the QPO frequencies. We have observed no candidate signals above a pre-determined threshold and our lowest upper limit was set by the 92.5 Hz QPO observed in the interval from 150 s to 260 s after the start of the flare. This bound corresponds to a (90% confidence) root-sum-squared amplitude h_rssdet^90% = 4.5e-22 strain Hz^-1/2 on the GW waveform strength in the detectable polarization state reaching our Hanford (WA) 4 km detector. We illustrate the astrophysical significance of the result via an estimated characteristic energy in GW emission that we would expect to be able to detect. The above result corresponds to 7.7e46 erg (= 4.3e-8 M_sun c^2), which is of the same order as the total (isotropic) energy emitted in the electromagnetic spectrum. This result provides a means to probe the energy reservoir of the source with the best upper limit on the GW waveform strength published and represents the first broadband asteroseismology measurement using a GW detector.
Phys. Rev. D 88, 122004
2013, Reviews of Modern Physics
2008, Classical and Quantum Gravity
The fourth science run of the {LIGO} and GEO 600 gravitational-wave detectors, carried out in early 2005, collected data with significantly lower noise than previous science runs. We report on a search for short-duration gravitational-wave bursts with arbitrary waveform in the 64-1600 Hz frequency range appearing in all three {LIGO} interferometers. Signal consistency tests, data quality cuts and auxiliary-channel vetoes
2009, Physical Review D
LIGO(Laser Interferometer Gravitational-Wave Observatory)[1] is composed of three laser interferometers at two sites in the United States of America. The interferometers known as H1, with 4 km arms, and H2, with 2 km arms, are co-located within the same vacuum system at the Hanford site in Washington state. An additional 4-kilometer-long interferometer, L1, is located in Louisiana's Livingston Parish. The detectors have similar orientation, as far as is possible given the curvature of the Earth's surface and the constraints of the sites on which ...
2009, Physical Review D
After many years of preparation, interferometric gravitational-wave (GW) detectors have now begun an era of long-duration observing. The three detectors of the Laser Interferometer Gravitational-Wave Observatory (LIGO)[1] reached their design sensitivity levels in 2005 and began a ''science run''that collected data through late 2007. This run is called…
2008, Classical and Quantum Gravity
Gravitational wave bursts are short duration perturbations of the spacetime metric due to such catastrophic astrophysical events as supernova core collapses [1] or the merger and ringdown phases of binary black hole coalescences [2, 3]. Over the past decade, the search for these signals has been independently performed by individual detectors or by homogeneous networks of resonant bars [4] or laser interferometers [5–9]. The first coincident burst analysis between interferometers with different broadband sensitivity and ...
2014, Physical Review Letters
2009, Classical and Quantum Gravity
A search for gravitational wave burst events has been performed with the Virgo C7 commissioning run data that have been acquired in September 2005 over 5 days. It focused on unmodeled short duration signals in the frequency range 150 Hz to 2 kHz. A search aimed at detecting the GW emission from the merger and ring-down phases of binary black hole coalescences was also carried out. An extensive understanding of the data was required to be able to handle a burst search using the output of only one detector. A 90% ...
2010, The Astrophysical Journal
Progenitor scenarios for short gamma-ray bursts (short GRBs) include coalescenses of two neutron stars or a neutron star and black hole, which would necessarily be accompanied by the emission of strong gravitational waves. We present a search for these known gravitational-wave signatures in temporal and directional coincidence with 22 GRBs that had sufficient gravitational-wave data available in multiple instruments during LIGO's fifth science run, S5, and Virgo's first science run, VSR1. We find no statistically ...
2010, Physical Review D
We present results from an all-sky search for unmodeled gravitational-wave bursts in the data collected by the LIGO, GEO 600 and Virgo detectors between November 2006 and October 2007. The search is performed by three different analysis algorithms over the frequency band 50-6000 Hz. Data are analyzed for times with at least two of the four LIGO-Virgo detectors in coincident operation, with a total live time of 266 days. No events produced by the search algorithms survive the selection cuts. We set a frequentist upper limit on the rate of gravitational-wave bursts impinging on our network of detectors. When combined with the previous LIGO search of the data collected between November 2005 and November 2006, the upper limit on the rate of detectable gravitational-wave bursts in the 64-2048 Hz band is 2.0 events per year at 90% confidence. We also present event rate versus strength exclusion plots for several types of plausible burst waveforms. The sensitivity of the combined search is expressed in terms of the root-sum-squared strain amplitude for a variety of simulated waveforms and lies in the range 6x10^-22 1/sqrt(Hz) to 2x10^-20 1/sqrt(Hz). This is the first untriggered burst search to use data from the LIGO and Virgo detectors together, and the most sensitive untriggered burst search performed so far.
2008, Classical and Quantum Gravity
2011, Physical Review D