Bulletin of the American Physical Society
2006 APS April Meeting
Saturday–Tuesday, April 22–25, 2006; Dallas, TX
Session S11: Sources of Gravitational Waves |
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Sponsoring Units: GGR Chair: John Baker, Goddard Space Flight Room: Hyatt Regency Dallas Cumberland E |
Monday, April 24, 2006 3:30PM - 3:42PM |
S11.00001: Search techniques for gravitational wave bursts from cosmic strings Xavier Siemens, Jolien Creighton, Irit Maor, Saikat Ray Majumder, Kipp Cannon, Jocelyn Read We discuss data analysis techniques that can be used in the search for gravitational wave bursts from cosmic strings. In the absence of a detection, we show how to set upper limits based on the loudest event. Using Initial LIGO sensitivity curves, we show that these upper limits may result in interesting constraints on the parameter space of theories that lead to the production of cosmic strings. [Preview Abstract] |
Monday, April 24, 2006 3:42PM - 3:54PM |
S11.00002: Self force on a particle in curved spacetime Swapnil Tripathi, Alan Wiseman, John Friedman, Tobias Keidl The finite part of the self force on a static scalar charge in a Schwarzschild spacetime is calculated here using a mode by mode expansion of Green's function. The Quinn-Wald axioms [2,3] have been used to regularize the self force. The directional part of the self force has been identified and substracted which simplfies the calculation a lot by making it possible to use symmetries. The motivation for this calculation is to develop techniques and formalism for use in calculations of the self forces (dissipative and conservative) acting on charges and masses moving in black hole spacetimes. \newline \newline [1] A.G. Wiseman, Phys. Rev. D61 (2000) 084014. \newline [2] T.C. Quinn, Phys. Rev. D62(2000) 064029. \newline [3] T.C. Quinn, R.M. Wald Phys. Rev. D56 (1997) 3381. [Preview Abstract] |
Monday, April 24, 2006 3:54PM - 4:06PM |
S11.00003: Static Electromagnetic and Gravitational Perturbations of Schwarzschild Spacetime Tobias Keidl, John Friedman, Swapnil Tripathi, Alan Wiseman This talk describes an explicit computation of the perturbed gravitational field of a static point mass and of the electromagnetic field of a point charge in Schwarzschild background. Starting from the Teukolsky equation \footnote{Teukolsky, S. A., Astrophys. J., \textbf{185}, 635-647, (1973)}, we calculate the gauge invariant Weyl Tensor components. By using free radial functions implicit in the Cohen-Kegeles prescription \footnote{Kegeles, L. S. and Cohen, J. M., Phys. Rev. D \textbf{19}, 1641-1664, (1979)}, and by adding a mass perturbation outside of the Cohen-Kegeles gauge one can construct a gauge in which the metric is regular. The result is subtle, involving the piecing together of gauges regular above and below the position of the particle. The method is likely to be valid for particles in a Kerr geometry. [Preview Abstract] |
Monday, April 24, 2006 4:06PM - 4:18PM |
S11.00004: Self-force in a gauge appropriate to separable wave equations John Friedman, Tobias Keidl, Swapnil Tripathi, Alan Wiseman, Samuel Gralla Gravitational waves from the inspiral of a stellar-size black hole to a supermassive black hole can be accurately approximated by a point particle moving in a Kerr background. The talk presents progress on computing the self-force in a gauge that is constructed from the gauge-invariant Weyl tensor. The gauge and the renormalization method are chosen to compute a perturbed metric and renormalized self-force from the Teukolsky equation. The method is related to earlier work by Cohen, Kegeles, Lousto, Detweiler, and Whiting, and to the MiSaTaQuWa renormalization. [Preview Abstract] |
Monday, April 24, 2006 4:18PM - 4:30PM |
S11.00005: Extreme mass ratio inspirals via a multiple time expansion Tanja Hinderer, Eanna Flanagan Extreme mass ratio inspirals such as a stellar mass compact object orbiting a massive black hole at the center of a galaxy are an important source for the planned space-based gravitational wave detector LISA. To extract information from the signal requires accurate theoretical models as templates for matched filtering. One of the approaches for generating detection templates, the use of conservation laws, relies on the adiabatic approximation and there are some concerns as to the reliability of this approximation because in the weak field regime, it neglects important contributions to the phase from conservative pieces of the self-acceleration. We analyze this problem using a multiple time expansion, which is a standard tool for describing dynamical systems. This method allows us to show rigorously that the adiabatic approximation correctly gives the leading order phasing and establishes a mathematical framework for calculating the post- adiabatic phasing needed for measurement templates. [Preview Abstract] |
Monday, April 24, 2006 4:30PM - 4:42PM |
S11.00006: The validity of the adiabatic approximation for extreme-mass ratio inspirals Marc Favata, Eanna Flanagan The inspiral of a compact object into a massive black hole is one of the primary sources of gravitational waves for the planned Laser Interferometer Space Antenna (LISA). The detection of these sources relies on the accurate modeling of the binary dynamics. A precise description of the binary orbit requires an evaluation of the self-force. The adiabatic approximation, which consists of using the time-averaged rates of change of the three conserved quantities for geodesic motion using a prescription derived by Mino, greatly simplifies computation of the orbital evolution. The accuracy of this approximation has been debated in the literature; in particular it has been suggested that the approximation is poor for eccentric orbits. Using post-Newtonian expansions we estimate the error in the waveform's phase for slightly eccentric orbits, generalizing previous estimates for circular orbits. The results indicate that adiabatic waveforms will likely be accurate enough for detection templates. We also show that the approximation becomes poor at low frequencies, in agreement with arguments of Pound, Poisson and Nickel; however those frequencies are outside LISA's waveband. [Preview Abstract] |
Monday, April 24, 2006 4:42PM - 4:54PM |
S11.00007: Perturbations of Schwarzschild black holes in the Lorenz gauge: Formulation and numerical implementation Carlos Lousto, Leor Barack We reformulate the theory of Schwarzschild black hole perturbations in terms of the metric perturbation in the Lorenz gauge. In this formulation, each tensor-harmonic mode of the perturbation is constructed algebraically from 10 scalar functions, satisfying a set of 10 wavelike equations, which are decoupled at their principal parts. We solve these equations using numerical evolution in the time domain, for the case of a pointlike test particle set in a circular geodesic orbit around the black hole. Our code uses characteristic coordinates, and incorporates a constraint damping scheme. The axially-symmetric, odd-parity modes of the perturbation are obtained analytically. The approach developed here is especially advantageous in applications requiring knowledge of the local metric perturbation near a point particle; in particular, it offers a useful framework for calculations of the gravitational self force. [Preview Abstract] |
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