Publications (26)95.3 Total impact
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Article: Searches for Gravitational Waves from Known Pulsars with Science Run 5 LIGO Data
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ABSTRACT: We present a search for gravitational waves from 116 known millisecond and young pulsars using data from the fifth science run of the LIGO detectors. For this search, ephemerides overlapping the run period were obtained for all pulsars using radio and X-ray observations. We demonstrate an updated search method that allows for small uncertainties in the pulsar phase parameters to be included in the search. We report no signal detection from any of the targets and therefore interpret our results as upper limits on the gravitational wave signal strength. The most interesting limits are those for young pulsars. We present updated limits on gravitational radiation from the Crab pulsar, where the measured limit is now a factor of 7 below the spin-down limit. This limits the power radiated via gravitational waves to be less than ~2% of the available spin-down power. For the X-ray pulsar J0537 – 6910 we reach the spin-down limit under the assumption that any gravitational wave signal from it stays phase locked to the X-ray pulses over timing glitches, and for pulsars J1913+1011 and J1952+3252 we are only a factor of a few above the spin-down limit. Of the recycled millisecond pulsars, several of the measured upper limits are only about an order of magnitude above their spin-down limits. For these our best (lowest) upper limit on gravitational wave amplitude is 2.3 × 10–26 for J1603 – 7202 and our best (lowest) limit on the inferred pulsar ellipticity is 7.0 × 10–8 for J2124 – 3358.The Astrophysical Journal 03/2010; 713(1):671. · 6.02 Impact Factor -
Article: Searches for gravitational waves from known pulsars with S5 LIGO data
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ABSTRACT: We present a search for gravitational waves from 116 known millisecond and young pulsars using data from the fifth science run of the LIGO detectors. For this search ephemerides overlapping the run period were obtained for all pulsars using radio and X-ray observations. We demonstrate an updated search method that allows for small uncertainties in the pulsar phase parameters to be included in the search. We report no signal detection from any of the targets and therefore interpret our results as upper limits on the gravitational wave signal strength. The most interesting limits are those for young pulsars. We present updated limits on gravitational radiation from the Crab pulsar, where the measured limit is now a factor of seven below the spin-down limit. This limits the power radiated via gravitational waves to be less than ~2% of the available spin-down power. For the X-ray pulsar J0537-6910 we reach the spin-down limit under the assumption that any gravitational wave signal from it stays phase locked to the X-ray pulses over timing glitches, and for pulsars J1913+1011 and J1952+3252 we are only a factor of a few above the spin-down limit. Of the recycled millisecond pulsars several of the measured upper limits are only about an order of magnitude above their spin-down limits. For these our best (lowest) upper limit on gravitational wave amplitude is 2.3x10^-26 for J1603-7202 and our best (lowest) limit on the inferred pulsar ellipticity is 7.0x10^-8 for J2124-3358.09/2009; -
Article: Search for gravitational-wave bursts associated with gamma-ray bursts using data from LIGO Science Run 5 and Virgo Science Run 1
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ABSTRACT: We present the results of a search for gravitational-wave bursts associated with 137 gamma-ray bursts (GRBs) that were detected by satellite-based gamma-ray experiments during the fifth LIGO science run and first Virgo science run. The data used in this analysis were collected from 2005 November 4 to 2007 October 1, and most of the GRB triggers were from the Swift satellite. The search uses a coherent network analysis method that takes into account the different locations and orientations of the interferometers at the three LIGO-Virgo sites. We find no evidence for gravitational-wave burst signals associated with this sample of GRBs. Using simulated short-duration (<1 s) waveforms, we set upper limits on the amplitude of gravitational waves associated with each GRB. We also place lower bounds on the distance to each GRB under the assumption of a fixed energy emission in gravitational waves, with typical limits of D ~ 15 Mpc (E_GW^iso / 0.01 M_o c^2)^1/2 for emission at frequencies around 150 Hz, where the LIGO-Virgo detector network has best sensitivity. We present astrophysical interpretations and implications of these results, and prospects for corresponding searches during future LIGO-Virgo runs.The Astrophysical Journal 08/2009; · 6.02 Impact Factor -
Article: An upper limit on the stochastic gravitational-wave background of cosmological origin.
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ABSTRACT: 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 the amplitude of this background are therefore of fundamental importance for understanding the evolution of the Universe when it was younger than one minute. Here we report limits on the amplitude of the stochastic gravitational-wave background using the data from a two-year science run of the Laser Interferometer Gravitational-wave Observatory (LIGO). Our result constrains the energy density of the stochastic gravitational-wave background normalized by the critical energy density of the Universe, in the frequency band around 100 Hz, to be <6.9 x 10(-6) at 95% confidence. The data rule out models of early Universe evolution with relatively large equation-of-state parameter, as well as cosmic (super)string models with relatively small string tension that are favoured in some string theory models. This search for the stochastic background improves on the indirect limits from Big Bang nucleosynthesis and cosmic microwave background at 100 Hz.Nature 08/2009; 460(7258):990-4. · 36.28 Impact Factor -
Article: An upper limit on the stochastic gravitational-wave background of cosmological origin
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ABSTRACT: 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 observationsNature 08/2009; 460(7258):990-994. · 36.28 Impact Factor -
Article: All-sky LIGO search for periodic gravitational waves in the early fifth-science-run data.
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ABSTRACT: We report on an all-sky search with the LIGO detectors for periodic gravitational waves in the frequency range 50-1100 Hz and with the frequency's time derivative in the range -5 x 10{-9}-0 Hz s{-1}. Data from the first eight months of the fifth LIGO science run (S5) have been used in this search, which is based on a semicoherent method (PowerFlux) of summing strain power. Observing no evidence of periodic gravitational radiation, we report 95% confidence-level upper limits on radiation emitted by any unknown isolated rotating neutron stars within the search range. Strain limits below 10{-24} are obtained over a 200-Hz band, and the sensitivity improvement over previous searches increases the spatial volume sampled by an average factor of about 100 over the entire search band. For a neutron star with nominal equatorial ellipticity of 10{-6}, the search is sensitive to distances as great as 500 pc.Physical Review Letters 04/2009; 102(11):111102. · 7.37 Impact Factor -
Article: Erratum: All-sky search for periodic gravitational waves in LIGO S4 data (Physical Review D (2008) 77 (022001))
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ABSTRACT: Export Date: 10 December 2012, Source: Scopus, Art. No.: 129904, CODEN: PRVDA, doi: 10.1103/PhysRevD.80.129904, Language of Original Document: EnglishPhysical Review D - Particles, Fields, Gravitation and Cosmology. 01/2009; 80(12). -
Article: Search of S3 LIGO data for gravitational wave signals from spinning black hole and neutron star binary inspirals
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ABSTRACT: We report on the methods and results of the first dedicated search for gravitational waves emitted during the inspiral of compact binaries with spinning component bodies. We analyze 788 hours of data collected during the third science run (S3) of the LIGO detectors. We searched for binary systems using a detection template family specially designed to capture the effects of the spin-induced precession of the orbital plane. We present details of the techniques developed to enable this search for spin-modulated gravitational waves, highlighting the differences between this and other recent searches for binaries with nonspinning components. The template bank we employed was found to yield high matches with our spin-modulated target waveform for binaries with masses in the asymmetric range 1.0M⊙<m1<3.0M⊙ and 12.0M⊙<m2<20.0M⊙ which is where we would expect the spin of the binary’s components to have a significant effect. We find that our search of S3 LIGO data has good sensitivity to binaries in the Milky Way and to a small fraction of binaries in M31 and M33 with masses in the range 1.0M⊙<m1, m2<20.0M⊙. No gravitational wave signals were identified during this search. Assuming a binary population with spinning components and Gaussian distribution of masses representing a prototypical neutron star–black hole system with m1≃1.35M⊙ and m2≃5M⊙, we calculate the 90%-confidence upper limit on the rate of coalescence of these systems to be 15.9 yr-1L10-1, where L10 is 1010 times the blue light luminosity of the Sun.Phys. Rev. D. 08/2008; 78(4). -
Article: A joint search for gravitational wave bursts with AURIGA and LIGO
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ABSTRACT: The first simultaneous operation of the AURIGA detector* and the LIGO observatory* was an opportunity to explore real data, joint analysis methods between two very different types of gravitational wave detectors: resonant bars and interferometers. This paper describes a coincident gravitational wave burst search, where data from the LIGO interferometers are cross-correlated at the time of AURIGA candidate events to identify coincident transients. The analysis pipeline is tuned with two thresholds, on the signal-to-noise ratio of AURIGA candidate events and on the significance of the cross-correlation test in LIGO. The false alarm rate is estimated by introducing time shifts between data sets and the network detection efficiency is measured by adding simulated gravitational wave signals to the detector output. The simulated waveforms have a significant fraction of power in the narrower AURIGA band. In the absence of a detection, we discuss how to set an upper limit on the rate of gravitational waves and to interpret it according to different source models. Due to the short amount of analyzed data and to the high rate of non-Gaussian transients in the detectors' noise at the time, the relevance of this study is methodological: this was the first joint search for gravitational wave bursts among detectors with such different spectral sensitivity and the first opportunity for the resonant and interferometric communities to unify languages and techniques in the pursuit of their common goal.Classical and Quantum Gravity 04/2008; 25(9):095004. · 3.32 Impact Factor -
Article: Search for gravitational waves associated with 39 gamma-ray bursts using data from the second, third, and fourth LIGO runs
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ABSTRACT: We present the results of a search for short-duration gravitational-wave bursts associated with 39 gamma-ray bursts (GRBs) detected by gamma-ray satellite experiments during LIGO’s S2, S3, and S4 science runs. The search involves calculating the crosscorrelation between two interferometer data streams surrounding the GRB trigger time. We search for associated gravitational radiation from single GRBs, and also apply statistical tests to search for a gravitational-wave signature associated with the whole sample. For the sample examined, we find no evidence for the association of gravitational radiation with GRBs, either on a single-GRB basis or on a statistical basis. Simulating gravitational-wave bursts with sine-Gaussian waveforms, we set upper limits on the root-sum-square of the gravitational-wave strain amplitude of such waveforms at the times of the GRB triggers. We also demonstrate how a sample of several GRBs can be used collectively to set constraints on population models. The small number of GRBs and the significant change in sensitivity of the detectors over the three runs, however, limits the usefulness of a population study for the S2, S3, and S4 runs. Finally, we discuss prospects for the search sensitivity for the ongoing S5 run, and beyond for the next generation of detectors.Phys. Rev. D. 03/2008; 77(6). -
Article: Search for gravitational waves from binary inspirals in S3 and S4 LIGO data
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ABSTRACT: We report on a search for gravitational waves from the coalescence of compact binaries during the third and fourth LIGO science runs. The search focused on gravitational waves generated during the inspiral phase of the binary evolution. In our analysis, we considered three categories of compact binary systems, ordered by mass: (i) primordial black hole binaries with masses in the range 0.35M⊙<m1, m2<1.0M⊙, (ii) binary neutron stars with masses in the range 1.0M⊙<m1, m2<3.0M⊙, and (iii) binary black holes with masses in the range 3.0M⊙<m1, m2<mmax with the additional constraint m1+m2<mmax, where mmax was set to 40.0M⊙ and 80.0M⊙ in the third and fourth science runs, respectively. Although the detectors could probe to distances as far as tens of Mpc, no gravitational-wave signals were identified in the 1364 hours of data we analyzed. Assuming a binary population with a Gaussian distribution around 0.75-0.75M⊙, 1.4-1.4M⊙, and 5.0-5.0M⊙, we derived 90%-confidence upper limit rates of 4.9 yr-1L10-1 for primordial black hole binaries, 1.2 yr-1L10-1 for binary neutron stars, and 0.5 yr-1L10-1 for stellar mass binary black holes, where L10 is 1010 times the blue-light luminosity of the Sun.Phys. Rev. D. 03/2008; 77(6). -
Article: Upper limit map of a background of gravitational waves
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ABSTRACT: We searched for an anisotropic background of gravitational waves usingdata from the LIGO S4 science run and a method that is optimizedfor point sources. This is appropriate if, for example, the gravitationalwave background is dominated by a small number of distinct astrophysical sources.No signal was seen. Upper limit maps were produced assuming two differentpower laws for the source strain power spectrum. For an f-3 power law and using the50 Hz to 1.8 kHz band the upper limits on the sourcestrain power spectrum vary between 1.2×10-48 Hz-1 (100 Hz/f)3 and 1.2×10-47 Hz-1 (100 Hz/f)3, depending on the position in the sky. Similarly,in the case of constant strain power spectrum, the upper limits vary between 8.5×10-49 Hz-1 and 6.1×10-48 Hz-1. As a side product a limiton an isotropic background of gravitational waves was also obtained. All limitsare at the 90% confidence level. Finally, as an application, we focused onthe direction of Sco-X1, the brightest low-mass x-ray binary. We compare theupper limit on strain amplitude obtained by this method to expectations basedon the x-ray flux from Sco-X1.Phys. Rev. D. 01/1970; 76(8). -
Article: First cross-correlation analysis of interferometric and resonant-bar gravitational-wave data for stochastic backgrounds
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ABSTRACT: Data from the LIGO Livingston interferometer and the ALLEGRO resonant-bar detector, taken during LIGO’s fourth science run, were examined for cross correlations indicative of a stochastic gravitational-wave background in the frequency range 850–950 Hz, with most of the sensitivity arising between 905 and 925 Hz. ALLEGRO was operated in three different orientations during the experiment to modulate the relative sign of gravitational-wave and environmental correlations. No statistically significant correlations were seen in any of the orientations, and the results were used to set a Bayesian 90% confidence level upper limit of Ωgw(f)≤1.02, which corresponds to a gravitational-wave strain at 915 Hz of 1.5×10-23 Hz-1/2. In the traditional units of h1002Ωgw(f), this is a limit of 0.53, 2 orders of magnitude better than the previous direct limit at these frequencies. The method was also validated with successful extraction of simulated signals injected in hardware and software.Phys. Rev. D. 01/1970; 76(2). -
Article: Search of S3 LIGO data for gravitational wave signals from spinning black hole and neutron star binary inspirals
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ABSTRACT: We report in the methods and results of the first dedicated search for gravitational waves emitted during the inspiral of compact binaries with spinning component bodies. We analyze 788 hours of data collected during the third science run (S3) of the LIGO detectors. We searched for binary systems using a detection template family specially designed to capture the effects of the spin-induced precession of the orbital plane. We present details of the techniques developed to enable this search for spin-modulated gravitational waves, highlighting the differences between this and other recent searches for binaries with nonspinning components. The template bank we employed was found to yield high matches with our spin-modulated target waveform for binaries with masses in the asymmetric range. 1.0 M ☉ < m <sub>1</sub> <3.0 M ☉ and 12.0 M ☉ < m <sub>2</sub> <20.0 M ☉ which is where we would expect the spin of the binary's components to have a significant effect. We find that our search of S3 LIGO data has good sensitivity to binaries in the Milky Way and to a small fraction of binaries in M31 and M33 with masses in the range 1.0 M ☉ < m <sub>1</sub>, m <sub>2</sub> < 20.0 M ☉. No gravitational wave signals were identified during this search. Assuming a binary population with spinning components and Gaussian distribution of masses representing a prototypical neutron star-black hole system with m <sub>1</sub> ≅ 1.35 M ☉ and m <sub>2</sub> ≅ 5 M ☉, we calculate the 90% confidence upper limit on the rate of coalescence of these systems to be 15.9 yr<sup>-1</sup> L<sub>10</sub><sup>-1</sup>, where L<sub>10</sub> is 10<sup>10</sup> times the blue light luminosity of the sun. -
Article: Implications for the origin of GRB 070201 from LIGO observations
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ABSTRACT: 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 within a 180 s long window around the time of GRB 070201. This result implies that a compact binary progenitor of GRB 070201, with masses in the range, M ☉ < m <sub>1</sub> < 3 M ☉ and 1 M ☉ < m <sub>2</sub> < 40 M ☉, located in M31 is excluded at >99% confidence. If the GRB 070201 progenitor was not in M31, then we can exclude a binary neutron star merger progenitor with distance D < 3.5 Mpc, assuming random inclination, at 90% confidence. The result also implies that an unmodeled gravitational-wave burst from GRB 070201 most probably emitted less than 4.4×10<sup>-4</sup> M ☉ c <sup>2</sup>(7.9×10<sup>50</sup>ergs) in any 100 ms long period within the signal region if the source was in M31 and radiated isotropically at the same frequency as LIGO's peak sensitivity ( f ≈Hz). This upper limit does not exclude current models of SGRs at the M31 distance. -
Article: LIGO: the Laser Interferometer Gravitational-Wave Observatory
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ABSTRACT: The goal of the Laser Interferometric Gravitational-Wave Observatory (LIGO) is to detect and study gravitational waves (GWs) of astrophysical origin. Direct detection of GWs holds the promise of testing general relativity in the strong-field regime, of providing a new probe of exotic objects such as black holes 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 one part in 10^(21). With this unprecedented sensitivity, the data are being analyzed to detect or place limits on GWs from a variety of potential astrophysical sources. -
Article: Search for gravitational waves from low mass compact binary coalescence in 186 days of LIGO's fifth science run
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ABSTRACT: We report on a search for gravitational waves from coalescing compact binaries, of total mass between 2 and 35M_☉, using LIGO observations between November 14, 2006 and May 18, 2007. No gravitational-wave signals were detected. We report upper limits on the rate of compact binary coalescence as a function of total mass. The LIGO cumulative 90%-confidence rate upper limits of the binary coalescence of neutron stars, black holes and black hole-neutron star systems are 1.4 × 10^(-2), 7.3 × 10(-4) and 3.6 × 10(-3) yr(-1) L_10^(-1), respectively, where L_(10_ is 10^(10) times the blue solar luminosity -
Article: Search for gravitational waves from low mass binary coalescences in the first year of LIGO's S5 data
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ABSTRACT: We have searched for gravitational waves from coalescing low mass compact binary systems with a total mass between 2M_([sun]) and 35Mz-([sun]) and a minimum component mass of 1M_([sun]) using data from the first year of the fifth science run of the three LIGO detectors, operating at design sensitivity. Depending on the mass, we are sensitive to coalescences as far as 150 Mpc from the Earth. No gravitational-wave signals were observed above the expected background. Assuming a population of compact binary objects with a Gaussian mass distribution representing binary neutron star systems, black hole–neutron star binary systems, and binary black hole systems, we calculate the 90% confidence upper limit on the rate of coalescences to be 3.9×10^(-2) yr^(-1)L_(10)^(-1), 1.1×10^(-2) yr^(-1)L_(10)^(-1), and 2.5×10^(-3)yr^(-1)L_(10)^(-1), respectively, where L_(10) is 10^(10) times the blue solar luminosity. We also set improved upper limits on the rate of compact binary coalescences per unit blue-light luminosity, as a function of mass. -
Article: All-Sky LIGO Search for Periodic Gravitational Waves in the Early Fifth-Science-Run Data
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ABSTRACT: We report on an all-sky search with the LIGO detectors for periodic gravitational waves in the frequency range 50–1100 Hz and with the frequency’s time derivative in the range -5 x 10^(-9)–0 Hzs^(-1). Data from the first eight months of the fifth LIGO science run (S5) have been used in this search, which is based on a semicoherent method (PowerFlux) of summing strain power. Observing no evidence of periodic gravitational radiation, we report 95% confidence-level upper limits on radiation emitted by any unknown isolated rotating neutron stars within the search range. Strain limits below 10^(-24) are obtained over a 200-Hz band, and the sensitivity improvement over previous searches increases the spatial volume sampled by an average factor of about 100 over the entire search band. For a neutron star with nominal equatorial ellipticity of 10^-6, the search is sensitive to distances as great as 500 pc. -
Article: Stacked Search for Gravitational Waves from the 2006 SGR 1900+14 Storm
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ABSTRACT: We present the results of a LIGO search for short-duration gravitational waves (GWs) associated with the 2006 March 29 SGR 1900+14 storm. A new search method is used, "stacking" the GW data around the times of individual soft-gamma bursts in the storm to enhance sensitivity for models in which multiple bursts are accompanied by GW emission. We assume that variation in the time difference between burst electromagnetic emission and potential burst GW emission is small relative to the GW signal duration, and we time-align GW excess power time-frequency tilings containing individual burst triggers to their corresponding electromagnetic emissions. We use two GW emission models in our search: a fluence-weighted model and a flat (unweighted) model for the most electromagnetically energetic bursts. We find no evidence of GWs associated with either model. Model-dependent GW strain, isotropic GW emission energy E_(GW), and γ ≡ E_(GW)/E_(EM) upper limits are estimated using a variety of assumed waveforms. The stacking method allows us to set the most stringent model-dependent limits on transient GW strain published to date. We find E_(GW) upper limit estimates (at a nominal distance of 10 kpc) of between 2 × 10^(45) erg and 6 × 10^(50) erg depending on the waveform type. These limits are an order of magnitude lower than upper limits published previously for this storm and overlap with the range of electromagnetic energies emitted in soft gamma repeater (SGR) giant flares.
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Institutions
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2009
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California Institute of Technology
Pasadena, CA, USA
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