Bulletin of the American Physical Society
2006 APS April Meeting
Saturday–Tuesday, April 22–25, 2006; Dallas, TX
Session P11: Focus Session: Space-Based Gravitational Wave Detection |
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Sponsoring Units: GGR Chair: John Friedman, University of Wisconsin at Madison Room: Hyatt Regency Dallas Cumberland E |
Monday, April 24, 2006 10:45AM - 11:21AM |
P11.00001: The LISA Observatory: Preparing for a bountiful harvest. Invited Speaker: The Laser Interferometer Space Antenna (LISA) will simultaneously detect many thousands of low frequency gravitational wave signals at high signal to noise. The science potential associated with this haul is tremendous, ranging from the exploration of galaxy formation through the observation of coalescing supermassive black hole binaries, through constraints on population synthesis models derived from a census of galactic binaries, to tests of fundamental physics using extreme mass ratio inspirals and optically resolved galactic binaries. Extracting all of this information from one or two time series poses a challenge that is very different to the one encountered with high frequency gravitational wave observations. I will describe recent progress in addressing the LISA data analysis problem, and our plans for a community wide effort to develop a full data analysis pipeline. [Preview Abstract] |
Monday, April 24, 2006 11:21AM - 11:33AM |
P11.00002: Using Gravitational Waves from Intermediate Mass Black Holes to Test the No Hair Theorem James Graber We used to think that supermassive black holes (SMBHs) were rare, perhaps only occurring in quasars. Now we think they are common, occurring in almost every galaxy. A similar change of opinion may soon occur concerning intermediate mass black holes (IMBHs), whose very existence is still in doubt. However, some evidence suggests there may be at least several IMBHs in every galaxy and other evidence suggests that IMBHs are frequent in globular clusters. If so, IMBH-SMBH mergers may be the most common high signal-to-noise ratio BH-BH merger events seen by LISA. It turns out that these intermediate mass ratio inspirals (IMRIs) can be used to make a very clean test of the black hole no-hair theorems by means of Ryan's method. (Ryan, F. D., \textit{Phys. Rev. D} \textbf{52}, 5707 (1995).) In this paper, we discuss using IMRIs to make this test. IMRIs may be easier to detect than extreme mass ratio inspirals (EMRIs) because they will have a higher signal to noise ratios than EMRIs at a comparable distance. The measure and dimensionality of the search space necessary to find EMRIs in the LISA data may also be significantly smaller than the search space necessary to find EMRIs, making them easier to find in the first place, and easier to analyze in the second place. We point out how to take advantage of these facts by focusing on gravitational waves from relatively early in the IMRI inspiral. [Preview Abstract] |
Monday, April 24, 2006 11:33AM - 11:45AM |
P11.00003: Observing the final moments of massive black hole mergers with LISA. John Baker Mergers of binary black hole systems are one of the strongest sources of gravitational radiation expected to be observed by LISA. Recent advances in modeling the final merger and ringdown of comparable-mass systems, particularly via numerical relativity simulations, are dramatically expanding our understanding of these systems and the radiation they generate. We summarize recent modeling results, highlighting the work of Goddard's numerical relativity group, and apply this emerging knowledge to the problem of observing the final moments of binary black hole mergers with LISA. [Preview Abstract] |
Monday, April 24, 2006 11:45AM - 11:57AM |
P11.00004: Darwin's Design: Genetic Algorithms and Likelihood Surfaces in LISA Data Analysis Jeff Crowder, Neil Cornish, Lucas Reddinger Thousands of low frequency gravitational wave sources will be detectable by the Laser Interferometer Space Antenna (LISA). A data analysis method has to be found to handle the large number of sources, many of which will have signals overlapping. This talk will focus on a new method for gravitational wave data analysis that provides simultaneous solutions for multiple sources within a chosen frequency band. This approach uses Genetic Algorithms (GAs) to perform searches of simulated LISA data. GAs show great promise in handling multiple source signals. Results, extracted from simulated LISA data, will be presented showing how GAs will be able to address the LISA low frequency problem of large numbers of overlapping signals. Additionally, this talk will discuss features of likelihood surfaces that exist for various sets of simulated LISA data, and how these features affect parameter extraction for all methods of data analysis. A comparison of several types of search techniques and how the likelihood surface features affect their efficacy will presented. [Preview Abstract] |
Monday, April 24, 2006 11:57AM - 12:09PM |
P11.00005: LISA Interferometer Test Bench at UF Sridhar Reddy Guntaka, Rachel J Cruz, J Ira Thorpe, Michael Hartman, David B Tanner, Guido Mueller LISA, a joint NASA/ESA space mission to detect gravitational waves in the 10$^{-4 }$to 10$^{-1 }$Hz frequency band, is scheduled to launch in 2015. LISA will consist of three spacecraft in a heliocentric orbit forming a triangle with a 5 Gm baseline. In order to detect gravitational waves, LISA will use laser interferometry to measure changes in spacecraft separations with pm accuracy. The interferometer signals will be dominated by laser frequency noise. The dominant laser frequency noise will be subtracted from the data stream by post-processing the data using time delay interferometry (TDI). This algorithm relies on a strong correlation between all LISA signals taken at different times and different spacecraft as well as on very low noise and large dynamic range phase meters and on accurate timing information. At the University of Florida, we are developing an experimental LISA simulator to test implementations of various aspects of LISA interferometry and TDI. Realistic light travel times between the spacecraft are simulated using an electronic phase delay technique. In this paper we will present preliminary results of an experimental implementation of TDI to test LISA-like signals in the laboratory. This work is supported by NASA grant BEFS04-0019-0019. [Preview Abstract] |
Monday, April 24, 2006 12:09PM - 12:21PM |
P11.00006: Progress towards experimental verification of arm-locking for LISA James Thorpe, Shawn Mytrik, Rachel Cruz, Guido Mueller The proposed space-based interferometric gravitational wave detector LISA will be used to study gravitational waves in the mHz regime. It consists of three spacecraft located at the vertices of a 5 Gm triangle, each containing two freely-falling proof masses. The distances between the proof masses will be monitored using laser interferometry in an effort to detect modulations due to gravitational waves. Orbital motion will cause arm-length mismatches in the constellation to a level of approximately 1{\%}, which will cause laser frequency noise to couple into the interferometer output. In order to achieve the sensitivity required to detect gravitational waves, the laser frequency noise must be suppressed to an acceptable level. One proposed technique for reducing laser frequency noise in LISA is arm-locking, wherein some combination of the LISA arms is used as a frequency reference. We propose a method for evaluating arm-locking in an electro-optic laboratory model of LISA. This model includes lasers with LISA-like noise characteristics as well as realistic light travel delays achieved using an electronic phase delay method [Class. Quantum Grav. 22 (2005) S227-S234]. Current progress and results will be presented. This work is supported by NASA grant BEFS04-0019-0019. [Preview Abstract] |
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