Publications (21)21.22 Total impact
-
Article: Implementation and testing of the first prompt search for gravitational wave transients with electromagnetic counterparts
[show abstract] [hide abstract]
ABSTRACT: Aims: A transient astrophysical event observed in both gravitational wave (GW) and electromagnetic (EM) channels would yield rich scientific rewards. A first program initiating EM follow-ups to possible transient GW events has been developed and exercised by the LIGO and Virgo community in association with several partners. In this paper, we describe and evaluate the methods used to promptly identify and localize GW event candidates and to request images of targeted sky locations. Methods: During two observing periods (Dec. 17, 2009 to Jan. 8, 2010 and Sep. 2 to Oct. 20, 2010), a low-latency analysis pipeline was used to identify GW event candidates and to reconstruct maps of possible sky locations. A catalog of nearby galaxies and Milky Way globular clusters was used to select the most promising sky positions to be imaged, and this directional information was delivered to EM observatories with time lags of about thirty minutes. A Monte Carlo simulation has been used to evaluate the low-latency GW pipeline's ability to reconstruct source positions correctly. 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.Astronomy and Astrophysics 03/2012; 539:124. · 4.59 Impact Factor -
Article: Implementation and testing of the first prompt search for gravitational wave transients with electromagnetic counterparts
[show abstract] [hide abstract]
ABSTRACT: Aims: A transient astrophysical event observed in both gravitational wave (GW) and electromagnetic (EM) channels would yield rich scientific rewards. A first program initiating EM follow-ups to possible transient GW events has been developed and exercised by the LIGO and Virgo community in association with several partners. In this paper, we describe and evaluate the methods used to promptly identify and localize GW event candidates and to request images of targeted sky locations. Methods: During two observing periods (Dec. 17, 2009 to Jan. 8, 2010 and Sep. 2 to Oct. 20, 2010), a low-latency analysis pipeline was used to identify GW event candidates and to reconstruct maps of possible sky locations. A catalog of nearby galaxies and Milky Way globular clusters was used to select the most promising sky positions to be imaged, and this directional information was delivered to EM observatories with time lags of about thirty minutes. A Monte Carlo simulation has been used to evaluate the low-latency GW pipeline's ability to reconstruct source positions correctly. 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.Astronomy and Astrophysics 03/2012; 539:124. · 4.59 Impact Factor -
Article: Calibration of the LIGO Gravitational Wave Detectors in the Fifth Science Run
[show abstract] [hide abstract]
ABSTRACT: The Laser Interferometer Gravitational Wave Observatory (LIGO) is a network of three detectors built to detect local perturbations in the space-time metric from astrophysical sources. These detectors, two in Hanford, WA and one in Livingston, LA, are power-recycled Fabry-Perot Michelson interferometers. In their fifth science run (S5), between November 2005 and October 2007, these detectors accumulated one year of triple coincident data while operating at their designed sensitivity. In this paper, we describe the calibration of the instruments in the S5 data set, including measurement techniques and uncertainty estimation. Comment: 49 pages, 23 figures07/2010; -
Article: First search for gravitational waves from the youngest known neutron star
[show abstract] [hide abstract]
ABSTRACT: We present a search for periodic gravitational waves from the neutron star in the supernova remnant Cassiopeia A. The search coherently analyzes data in a 12 day interval taken from the fifth science run of the Laser Interferometer Gravitational-Wave Observatory. It searches gravitational-wave frequencies from 100 to 300 Hz and covers a wide range of first and second frequency derivatives appropriate for the age of the remnant and for different spin-down mechanisms. No gravitational-wave signal was detected. Within the range of search frequencies, we set 95% confidence upper limits of (0.7-1.2) × 10^-24 on the intrinsic gravitational-wave strain, (0.4-4) × 10^-4 on the equatorial ellipticity of the neutron star, and 0.005-0.14 on the amplitude of r-mode oscillations of the neutron star. These direct upper limits beat indirect limits derived from energy conservation and enter the range of theoretical predictions involving crystalline exotic matter or runaway r-modes. This paper is also the first gravitational-wave search to present upper limits on the r-mode amplitude.The Astrophysical Journal 06/2010; 722(2):1504. · 6.02 Impact Factor -
Article: Predictions for the Rates of Compact Binary Coalescences Observable by Ground-based Gravitational-wave Detectors
[show abstract] [hide abstract]
ABSTRACT: We present an up-to-date, comprehensive summary of the rates for all types of compact binary coalescence sources detectable by the Initial and Advanced versions of the ground-based gravitational-wave detectors LIGO and Virgo. Astrophysical estimates for compact-binary coalescence rates depend on a number of assumptions and unknown model parameters, and are still uncertain. The most confident among these estimates are the rate predictions for coalescing binary neutron stars which are based on extrapolations from observed binary pulsars in our Galaxy. These yield a likely coalescence rate of 100 per Myr per Milky Way Equivalent Galaxy (MWEG), although the rate could plausibly range from 1 per Myr per MWEG to 1000 per Myr per MWEG. We convert coalescence rates into detection rates based on data from the LIGO S5 and Virgo VSR2 science runs and projected sensitivities for our Advanced detectors. Using the detector sensitivities derived from these data, we find a likely detection rate of 0.02 per year for Initial LIGO-Virgo interferometers, with a plausible range between 0.0002 and 0.2 per year. The likely binary neutron-star detection rate for the Advanced LIGO-Virgo network increases to 40 events per year, with a range between 0.4 and 400 per year.03/2010; -
Article: LOOC-UP: Seeking Optical Counterparts to Gravitational-Wave Signal Candidates
[show abstract] [hide abstract]
ABSTRACT: The large gravitational-wave detectors in the U.S. and Europe are now collecting data and searching for the gravitational signatures of compact binary mergers, stellar core collapse, black hole creation, and other highly energetic astrophysical events. One part of this effort is an attempt to Locate and Observe Optical Counterparts to Unmodeled Pulses of gravitational waves, by enlisting wide-field optical telescopes to promptly capture images of the sky positions reconstructed for gravitational-wave signal candidates. A transient optical counterpart, if detected, could help confirm a signal candidate as a real event and would yield valuable information about the progenitor and the astrophysics of the event. This poster will describe the methods and current operation of the LOOC-UP project. This work is supported by the National Science Foundation and other funding agencies worldwide.12/2009; 42:230. -
Article: Search for gravitational-wave bursts associated with gamma-ray bursts using data from LIGO Science Run 5 and Virgo Science Run 1
[show abstract] [hide abstract]
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: Einstein@Home search for periodic gravitational waves in early S5 LIGO data
[show abstract] [hide abstract]
ABSTRACT: This paper reports on an all-sky search for periodic gravitational waves from sources such as deformed isolated rapidly-spinning neutron stars. The analysis uses 840 hours of data from 66 days of the fifth LIGO science run (S5). The data was searched for quasi-monochromatic waves with frequencies f in the range from 50 Hz to 1500 Hz, with a linear frequency drift \dot{f} (measured at the solar system barycenter) in the range -f/\tau < \dot{f} < 0.1 f/\tau, for a minimum spin-down age \tau of 1000 years for signals below 400 Hz and 8000 years above 400 Hz. The main computational work of the search was distributed over approximately 100000 computers volunteered by the general public. This large computing power allowed the use of a relatively long coherent integration time of 30 hours while searching a large parameter space. This search extends Einstein@Home's previous search in LIGO S4 data to about three times better sensitivity. No statistically significant signals were found. In the 125 Hz to 225 Hz band, more than 90% of sources with dimensionless gravitational-wave strain tensor amplitude greater than 3e-24 would have been detected.05/2009; -
Article: Search for High Frequency Gravitational Wave Bursts in the First Calendar Year of LIGO's Fifth Science Run
[show abstract] [hide abstract]
ABSTRACT: We present an all-sky search for gravitational waves in the frequency range 1 to 6 kHz during the first calendar year of LIGO's fifth science run. This is the first untriggered LIGO burst analysis to be conducted above 3 kHz. We discuss the unique properties of interferometric data in this regime. 161.3 days of triple-coincident data were analyzed. No gravitational events above threshold were observed and a frequentist upper limit of 5.4 events per year on the rate of strong gravitational wave bursts was placed at a 90% confidence level. Implications for specific theoretical models of gravitational wave emission are also discussed. Comment: 13 pages, accepted for publication in Physical Review D04/2009; -
Article: Search for gravitational-wave bursts in the first year of the fifth LIGO science run
[show abstract] [hide abstract]
ABSTRACT: We present the results obtained from an all-sky search for gravitational-wave (GW) bursts in the 64-2000 Hz frequency range in data collected by the LIGO detectors during the first year (November 2005 - November 2006) of their fifth science run. The total analyzed livetime was 268.6 days. Multiple hierarchical data analysis methods were invoked in this search. The overall sensitivity expressed in terms of the root-sum-square (rss) strain amplitude h_{rss} for gravitational-wave bursts with various morphologies was in the range of 6 times 10^{-22} Hz^{-1/2} to a few times 10^{-21} Hz^{-1/2}. No GW signals were observed and a frequentist upper limit of 3.6 events per year on the rate of strong GW bursts was placed at the 90% confidence level. As in our previous searches, we also combined this rate limit with the detection efficiency for selected waveform morphologies to obtain event rate versus strength exclusion curves. In sensitivity, these exclusion curves are the most stringent to date. Comment: v3: various figure and text edits; submitted to PRD; 26 pages04/2009; -
Article: First LIGO search for gravitational wave bursts from cosmic (super)strings
[show abstract] [hide abstract]
ABSTRACT: We report on a matched-filter search for gravitational wave bursts from cosmic string cusps using LIGO data from the fourth science run (S4) which took place in February and March 2005. No gravitational waves were detected in 14.9 days of data from times when all three LIGO detectors were operating. We interpret the result in terms of a frequentist upper limit on the rate of gravitational wave bursts and use the limits on the rate to constrain the parameter space (string tension, reconnection probability, and loop sizes) of cosmic string models. Comment: 11 pages, 3 figures. Replaced with version submitted to PRD04/2009; -
Article: Search for Gravitational Waves from Low Mass Binary Coalescences in the First Year of LIGO's S5 Data
[show abstract] [hide abstract]
ABSTRACT: We have searched for gravitational waves from coalescing low mass compact binary systems with a total mass between 2 and 35 Msun and a minimum component mass of 1 Msun using data from the first year of the fifth science run (S5) of the three LIGO detectors, operating at design sensitivity. Depending on 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 compact binary objects population 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 \times 10^{-2} yr^{-1} L_{10}^{-1}, 1.1 \times 10^{-2} yr^{-1} L_{10}^{-1}, and 2.5 \times 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. Comment: 15 pages, 5 figures, 2 tables; changes associated with referee comments, inclusion of recent LIGO calibration data, fixing small error in upper limit calculation01/2009; -
Article: All-sky search for periodic gravitational waves in LIGO S4 data
[show abstract] [hide abstract]
ABSTRACT: We report on an all-sky search with the LIGO detectors for periodic gravitational waves in the frequency range 50-1000 Hz and with the frequency's time derivative in the range -1.0E-8 Hz/s to zero. Data from the fourth LIGO science run (S4) have been used in this search. Three different semi-coherent methods of transforming and summing strain power from Short Fourier Transforms (SFTs) of the calibrated data have been used. The first, known as "StackSlide", averages normalized power from each SFT. A "weighted Hough" scheme is also developed and used, and which also allows for a multi-interferometer search. The third method, known as "PowerFlux", is a variant of the StackSlide method in which the power is weighted before summing. In both the weighted Hough and PowerFlux methods, the weights are chosen according to the noise and detector antenna-pattern to maximize the signal-to-noise ratio. The respective advantages and disadvantages of these methods are discussed. Observing no evidence of periodic gravitational radiation, we report upper limits; we interpret these as limits on this radiation from isolated rotating neutron stars. The best population-based upper limit with 95% confidence on the gravitational-wave strain amplitude, found for simulated sources distributed isotropically across the sky and with isotropically distributed spin-axes, is 4.28E-24 (near 140 Hz). Strict upper limits are also obtained for small patches on the sky for best-case and worst-case inclinations of the spin axes. Comment: 39 pages, 41 figures An error was found in the computation of the C parameter defined in equation 44 which led to its overestimate by 2^(1/4). The correct values for the multi-interferometer, H1 and L1 analyses are 9.2, 9.7, and 9.3, respectively. Figure 32 has been updated accordingly. None of the upper limits presented in the paper were affected08/2007; -
Article: Joint LIGO and TAMA300 Search for Gravitational Waves from Inspiralling Neutron Star Binaries
[show abstract] [hide abstract]
ABSTRACT: We search for coincident gravitational wave signals from inspiralling neutron star binaries using LIGO and TAMA300 data taken during early 2003. Using a simple trigger exchange method, we perform an inter-collaboration coincidence search during times when TAMA300 and only one of the LIGO sites were operational. We find no evidence of any gravitational wave signals. We place an observational upper limit on the rate of binary neutron star coalescence with component masses between 1 and 3 M_sun of 49 per year per Milky Way equivalent galaxy at a 90% confidence level. The methods developed during this search will find application in future network inspiral analyses.01/2006; -
Article: Search for gravitational wave bursts in LIGO's third science run
[show abstract] [hide abstract]
ABSTRACT: We report on a search for gravitational wave bursts in data from the three LIGO interferometric detectors during their third science run. The search targets subsecond bursts in the frequency range 100-1100 Hz for which no waveform model is assumed, and has a sensitivity in terms of the root-sum-square (rss) strain amplitude of hrss ~ 10^{-20} / sqrt(Hz). No gravitational wave signals were detected in the 8 days of analyzed data.11/2005; -
Article: Search for gravitational waves from binary black hole inspirals in LIGO data
[show abstract] [hide abstract]
ABSTRACT: We report on a search for gravitational waves from binary black hole inspirals in the data from the second science run of the LIGO interferometers. The search focused on binary systems with component masses between 3 and 20 solar masses. Optimally oriented binaries with distances up to 1 Mpc could be detected with efficiency of at least 90%. We found no events that could be identified as gravitational waves in the 385.6 hours of data that we searched. Comment: 18 pages, 8 figures09/2005; -
Article: Upper limits from the LIGO and TAMA detectors on the rate of gravitational-wave bursts
[show abstract] [hide abstract]
ABSTRACT: We report on the first joint search for gravitational waves by the TAMA and LIGO collaborations. We looked for millisecond-duration unmodelled gravitational-wave bursts in 473 hr of coincident data collected during early 2003. No candidate signals were found. We set an upper limit of 0.12 events per day on the rate of detectable gravitational-wave bursts, at 90% confidence level. From simulations, we estimate that our detector network was sensitive to bursts with root-sum-square strain amplitude above approximately 1-3x10^{-19} Hz^{-1/2} in the frequency band 700-2000 Hz. We describe the details of this collaborative search, with particular emphasis on its advantages and disadvantages compared to searches by LIGO and TAMA separately using the same data. Benefits include a lower background and longer observation time, at some cost in sensitivity and bandwidth. We also demonstrate techniques for performing coincidence searches with a heterogeneous network of detectors with different noise spectra and orientations. These techniques include using coordinated signal injections to estimate the network sensitivity, and tuning the analysis to maximize the sensitivity and the livetime, subject to constraints on the background.08/2005; -
Article: Joint LIGO and TAMA300 search for gravitational waves from inspiralling neutron star binaries
-
Article: The Einstein@Home search for periodic gravitational waves in early S5 LIGO data
[show abstract] [hide abstract]
ABSTRACT: This paper reports on an all-sky search for periodic gravitational waves from sources such as deformed isolated rapidly spinning neutron stars. The analysis uses 840 hours of data from 66 days of the fifth LIGO science run (S5). The data were searched for quasimonochromatic waves with frequencies f in the range from 50 to 1500 Hz, with a linear frequency drift f-dot (measured at the solar system barycenter) in the range -f/tau<f-dot <0.1f/tau, for a minimum spin-down age tau of 1000 years for signals below 400 Hz and 8000 years above 400 Hz. The main computational work of the search was distributed over approximately 100 000 computers volunteered by the general public. This large computing power allowed the use of a relatively long coherent integration time of 30 hours while searching a large parameter space. This search extends Einstein@Home's previous search in LIGO S4 data to about 3 times better sensitivity. No statistically significant signals were found. In the 125–225 Hz band, more than 90% of sources with dimensionless gravitational-wave strain tensor amplitude greater than 3×10-24 would have been detected.Physical Review D, v.80 (2009). -
Article: Erratum: Beating the spin-down limit on gravitational wave emission from the Crab pulsar
Astrophysical Journal Letters, v.706, L203-L204 (2009).
