Bulletin of the American Physical Society
2007 APS April Meeting
Volume 52, Number 3
Saturday–Tuesday, April 14–17, 2007; Jacksonville, Florida
Session R12: Gravitational Waves For and By LIGO |
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Sponsoring Units: GGR Chair: Peter Shawhan, University of Maryland Room: Hyatt Regency Jacksonville Riverfront City Terrace 8 |
Monday, April 16, 2007 10:45AM - 10:57AM |
R12.00001: Search for compact binary systems during LIGO's fifth science run Drew Keppel We report on a search for gravitational waves from the coalescence of stellar mass compact binaries (neutron stars and black holes) during the fifth LIGO science run. The search focuses on gravitational waves generated during the inspiral phase of the binary evolution. We look for coincidences between at least two of the three LIGO detectors. We describe the status search for these binary systems. [Preview Abstract] |
Monday, April 16, 2007 10:57AM - 11:09AM |
R12.00002: Noise transients and veto studies in the search for gravitational wave bursts with LIGO Shantanu Desai In November 2005 LIGO started a long science run (called S5) in order to collect one year of coincident data at design sensitivity. This talk will present results from various online and offline tools used to monitor the data quality, sensitivity to astrophysical searches and day-to-day performance of the interferometers. We shall focus on the salient features and identified causes of outlier noise transients that are detected by various algorithms in gravitational wave burst searches. We will also describe methods used to veto noise transients, and present their performance in S5 LIGO burst searches. [Preview Abstract] |
Monday, April 16, 2007 11:09AM - 11:21AM |
R12.00003: Gravitational Wave Burst Search in LIGO's Fifth Science Run Laura Cadonati We report on an ongoing search for gravitational wave bursts in LIGO's fifth science run, during which the LIGO interferometers are collecting one year of coincident data at design sensitivity. The LIGO burst search targets gravitational wave transients whose waveform and population are not well known, such as core-collapse supernovae or binary black hole mergers. Its ``eyes-wide-open'' approach was developed by the LIGO scientific collaboration over the past five years; only minimal assumptions are made on waveform or source population and detection depends on finding simultaneous statistically significant excesses of power in the three LIGO interferometers. Coherent follow-ups, consistency criteria and veto conditions effectively suppress false alarms. The talk will describe this analysis and its performance, report its preliminary results and briefly discuss its prospects. [Preview Abstract] |
Monday, April 16, 2007 11:21AM - 11:33AM |
R12.00004: Coherent all-sky search for gravitational wave bursts with the LIGO, GEO and VIRGO detectors Igor Yakushin The fifth science run of the LIGO instruments, S5, started in November 2005, is still in progress and is expected to collect one year of coincidence data. The GEO detector in Germany has also collected data during most of the S5 run. The VIRGO detector in Italy is nearing design sensitivity and we plan to exchange data and do joint LIGO-GEO-VIRGO analyses. We discuss the benefits of applying coherent methods to the search for gravitational wave bursts on data from networks of detectors that are misaligned and have different sensitivities. We present a preliminary analysis of the S5 data with a coherent network algorithm based on the constraint likelihood method. We describe the analysis pipeline, called coherent WaveBurst, which is designed for un-triggered all-sky burst searches with networks of gravitational wave detectors. The pipeline performs identification of burst events and reconstruction of gravitational wave polarizations and source location in the sky. We estimate the performance of the coherent burst search including estimation of the false alarm rate and detection efficiency for simulated burst signals. [Preview Abstract] |
Monday, April 16, 2007 11:33AM - 11:45AM |
R12.00005: Searching for Gravitational Wave Repeaters John Dwyer, Zsuzsa Marka, Luca Matone, Susie Bedikian, Szabolcs Marka We describe a search method for finding gravitational waves and evaluate its performance on realistic simulated LIGO data. The method is designed to find locations in the sky that repeatedly emitted gravitational waves whose amplitude was close to the detector sensitivity limit. We build on information recorded by burst data reduction algorithms scanning the output of the LIGO detectors while imposing strict coincidence (e.g. time and frequency) criteria. Sky pointing is derived through the precise measurement of relative time delays of the candidate events between LIGO's two 4 km detectors using rank-correlation. The natural consequence of the two-detector LIGO network is that a ring-like probability distribution on the celestial sphere is provided for each candidate event. After collecting the candidate events for the observation period, the point by point significance for each location in the celestial sphere is calculated against the background to potentially reveal the presence of a gravitational wave repeater. [Preview Abstract] |
Monday, April 16, 2007 11:45AM - 11:57AM |
R12.00006: Matched Filtering and Convergence of Numerical Relativity Templates Deirdre Shoemaker Tremendous progress has been achieved recently towards the solution of the binary black hole problem. We are now in the position of quantifying the quality of the numerical relativity waveforms when used for data analysis. This paper presents a study that establishes a connection between the convergence of numerical waveforms and the matched filtering properties commonly used in data analysis. In particular, we focus attention on the impact of phase errors since these errors play a dominant role in simulations of binaries with large initial separations of the black holes. We also present a summary of our recent binary black hole evolutions. [Preview Abstract] |
Monday, April 16, 2007 11:57AM - 12:09PM |
R12.00007: Towards a wave extraction method for Numerical Relativity: Estimating the gravitational wave content of spatial hypersurfaces Lior M. Burko We extract the Weyl scalars in the quasi-Kinnersley (qK) tetrad by finding first the (gauge--, tetrad--, and background--independent) transverse qK frame. This extraction still leaves two undetermined degrees of freedom: the ratio $|\Psi_0|/|\Psi_4|$, and one of the phases. The residual symmetry can be removed by gauge fixing of spin coefficients in two steps: First, we break the boost symmetry by requiring that $\rho$ (or alternatively $\mu$) corresponds to a global constant mass parameter that equals the ADM mass. Second, we break the spin symmetry by requiring that $\pi/\tau$ gives the expected polarization state for the gravitational waves. While the total emitted energy is independent of this second step of gauge fixing, its distribution between the $h_+,h_{\times}$ polarization states is not. We argue that a physical assumption on the polarization of the waves needs to be made. Our method of gauge fixing, specifically its second step, is appropriate for cases for which the Weyl curvature is purely electric. When the magnetic part does not vanish, $\pi$ and $\tau$ may have non-coinciding zeros, thus hindering the use of their ratio. Applying this method to Misner and Brill--Lindquist data, we explicitly find the Weyl scalars $\psi_0$ and $\psi_4$ in the qK tetrad. We also reaffirm that Misner data have more radiation present on the initial time slice. We find the Weyl scalars purely from spatial data, without evolving the field equations. [Preview Abstract] |
Monday, April 16, 2007 12:09PM - 12:21PM |
R12.00008: How far away is far enough for extracting numerical waveforms and how much do they depend on the extraction method? Enrique Pazos, Nils Dorband, Alessandro Nagar, Carlos Palenzuela, Erik Schnetter, Manuel Tiglio We present a method for extracting gravitational waves from numerical spacetimes which generalizes and refines one of the standard methods based on the Regge--Wheeler--Zerilli perturbation formalism. At the analytical level, this generalization allows a much more general class of slicing conditions for the background geometry, and is thus not restricted to Schwarzschild--like coordinates. At the numerical level, our approach uses high order multi-block methods, which improve both the accuracy of our simulations and of our extraction procedure. In particular, the latter is simplified since there is no need for interpolation, and we can afford to extract accurate waves at large radii with only little additional computational effort. We then present fully nonlinear three-dimensional numerical evolutions of a distorted Schwarzschild black hole in Kerr--Schild coordinates with an odd parity perturbation and analyze the improvement we gain from our generalized wave extraction, comparing our new method to the standard one. We do so by comparing the extracted waves with one-dimensional high resolution solutions of the corresponding generalized Regge--Wheeler equation. [Preview Abstract] |
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