Bulletin of the American Physical Society
APS April Meeting 2015
Volume 60, Number 4
Saturday–Tuesday, April 11–14, 2015; Baltimore, Maryland
Session R13: Gravitational Waveforms and Perturbation Theory |
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Sponsoring Units: GGR Chair: Scott Field, Cornell University Room: Key 9 |
Monday, April 13, 2015 10:45AM - 10:57AM |
R13.00001: Secular gravitational-wave phasing to 3PN order for low-eccentricity inspiraling binaries Blake Moore, Marc Favata, K. G. Arun, Chandra Mishra While gravitational waves cause binaries to circularize, several astrophysical scenarios suggest that some binaries will have non-negligible eccentricities when entering the LIGO frequency band. Time-domain waveforms for arbitrary eccentricity and to 3PN order are provided by the quasi-Keplerian formalism, but are computationally costly. Here we use a simplification of the quasi-Keplerian formalism to produce a fast, analytic waveform for the secular phasing of low-eccentricity binaries to 3PN order. We will discuss how this waveform is constructed, its domain of validity, and possible applications. [Preview Abstract] |
Monday, April 13, 2015 10:57AM - 11:09AM |
R13.00002: Eccentric Post-Newtonian Bursts Nicholas Loutrel, Nicolas Yunes, Frans Pretorius Gravitational wave emission from eccentric compact binaries is highly peaked around pericenter passage. As such, the gravitational wave signal looks like a sequence of discrete bursts in time-frequency space, as opposed to a continuous signal. Due to the relatively low power contained in each burst, standard matched filtering techniques may be impractical for extracting the parameters of the signal. Alternatively, one can stack the power within each burst, creating an enhanced data product and amplifying the signal-to-noise ratio. In order to do this, however, one must have some prior knowledge of where the bursts will occur in time-frequency space, i.e. a burst model. We here discuss a new method of constructing burst models that allows for a formulation at generic post-Newtonian (PN) order. We discuss its implementation at 3PN order and the accuracy of the full 3PN model by comparison to different eccentric PN Taylor approximants. [Preview Abstract] |
Monday, April 13, 2015 11:09AM - 11:21AM |
R13.00003: Spin effects in the nonlinear gravitational-wave memory from inspiralling binaries Marc Favata, Xinyi Guo The gravitational-wave memory effect is a time-varying but non-oscillatory contribution to the gravitational-wave amplitude. The nonlinear form of the memory arises from the gravitational waves produced by previously emitted gravitational waves. Despite the fact that it originates from higher-order interactions, it modifies the gravitational-waveform at leading (0PN) order. Understanding the memory is important for building accurate knowledge of the gravitational-wave signal in order to probe the nonlinearity of general relativity. Previous analytic calculations of spinning binary waveforms have neglected the memory component. Here we compute the memory corrections to the waveform due to spin-orbit interactions. We consider both aligned and precessing spin configurations. [Preview Abstract] |
Monday, April 13, 2015 11:21AM - 11:33AM |
R13.00004: Nonlinear gravitational-wave memory from merging binary black holes Goran Dojcinoski, Marc Favata The nonlinear memory effect is a nonoscillatory piece of the gravitational-wave signal that arises when gravitational waves themselves produce gravitational waves. Merging binary black holes produce the strongest nonlinear memory signal. However, many numerical relativity simulations have difficulty computing the memory modes. We use a semianalytic procedure to construct the memory modes from the nonmemory modes of several nonspinning, quasicircular black hole binaries. We then fit analytic functions to these numerically generated waveforms. Our results could be used to improve estimates of the detectability of the memory effect. [Preview Abstract] |
Monday, April 13, 2015 11:33AM - 11:45AM |
R13.00005: Effective potentials and morphological transitions for binary black-hole spin precession Michael Kesden, Davide Gerosa, Richard O'Shaughnessy, Emanuele Berti, Ulrich Sperhake We derive an effective potential $\xi_\pm(S)$ for binary black-hole (BBH) spin precession as a function of the magnitude of the total spin $S$. This allows us to solve the 2PN orbit-averaged spin-precession equations analytically for arbitrary BBH mass ratios and spins. These solutions are quasiperiodic functions of time: after a period $\tau$ the spins return to their initial relative orientations and precess about the total angular momentum by an angle $\alpha$. We classify BBH spin precession into three distinct morphologies between which BBHs can transition during their inspiral. Our new solutions constitute fundamental progress in our understanding of BBH spin precession and also have important applications to astrophysical BBHs. We derive a precession-averaged evolution equation for the total angular momentum that can be integrated on the radiation-reaction time, allowing us to statistically track BBH spins from formation to merger far more efficiently than was possible with previous orbit-averaged precession equations. This will greatly help us predict the signatures of BBH formation in the GWs emitted near merger and the distributions of final spins and gravitational recoils. The solutions may also help efforts to model and interpret GWs from generic BBH mergers. [Preview Abstract] |
Monday, April 13, 2015 11:45AM - 11:57AM |
R13.00006: Higher order spin effects in inspiralling compact objects binaries Sylvain Marsat We present recent progress on higher order spin effects in the post-Newtonian dynamics of compact objects binaries. We present first an extension of a Lagrangian formalism for point particle with spins, where finite size effects are represented by an additional multipolar structure. When applied to the case of a spin-induced octupole, the formalism allows for the computation of the cubic-in-spin effects that enter at the order 3.5PN. We also report on results obtained for quadratic-in-spin effects at the next-to-leading order 3PN. In both cases, we recover existing results for the dynamics, and derive for the first time the gravitational wave energy flux and orbital phasing. These results will be useful for the data analysis of the upcoming generation of advanced detectors of gravitational waves. [Preview Abstract] |
Monday, April 13, 2015 11:57AM - 12:09PM |
R13.00007: Tidal invariants for compact binaries on quasi-circular orbits Niels Warburton, Sam Dolan, Patrick Nolan, Adrian Ottewill, Barry Wardell We extend the gravitational self-force approach to encompass `self-interaction' tidal effects for a compact body of mass $\mu$ on a quasi-circular orbit around a black hole of mass $M \gg \mu$. Specifically, we define and calculate at $O(\mu)$ (conservative) shifts in the eigenvalues of the electric- and magnetic-type tidal tensors, and a (dissipative) shift in a scalar product between their eigenbases. This approach yields four gauge-invariant functions, from which one may construct other tidal quantities such as the curvature scalars and the speciality index. First, we analyze the general case of a geodesic in a regular perturbed vacuum spacetime admitting a helical Killing vector and a reflection symmetry. Next, we specialize to focus on circular orbits in the equatorial plane of Kerr spacetime at $O(\mu)$. We present accurate numerical results for the Schwarzschild case for orbital radii up to the light-ring, calculated via independent implementations in Lorenz and Regge-Wheeler gauges. We show that our results are consistent with leading-order post-Newtonian expansions, and demonstrate the existence of additional structure in the strong-field regime. We anticipate that our strong-field results will inform (e.g.)~effective one-body models for the gravitational two-body probl [Preview Abstract] |
Monday, April 13, 2015 12:09PM - 12:21PM |
R13.00008: Computing the dissipative part of the gravitational self force: I. Formalism Eanna Flanagan, Tanja Hinderer, Scott A. Hughes, Uchupol Ruangsri The computation of the gravitational self-force acting on a point particle inspiralling into a spinning black hole is a subject of much current research, and is relevant to future gravitational wave observations. We develop a formalism for numerically computing the dissipative part of the self-force for generic orbits, omitting the conservative part. The dissipative part contains both orbit-averaged and oscillatory pieces, is sufficient to compute the leading order, adiabatic inspiral, and will also yield information about the kicks to the particle's energy and angular momentum that occur during transient resonances. The dissipative self-force can be computed from the half-advanced minus half-retarded prescription, for which no regularization is needed. The method involves a simple modification of frequency domain Teukolsky codes that compute the retarded linearized metric perturbation, in which a more general type of mode amplitude is computed. In the future, it may be possible to develop complementary methods to compute the conservative part only, which are simpler than methods currently under development that aim to compute the entire first order self-force. [Preview Abstract] |
Monday, April 13, 2015 12:21PM - 12:33PM |
R13.00009: Computing the dissipative part of the gravitational self force: II. Numerical implementation and preliminary results Scott Hughes, Eanna Flanagan, Tanja Hinderer, Uchupol Ruangsri We describe how we have modified a frequency-domain Teukolsky-equation solver, previously used for computing orbit-averaged dissipation, in order to compute the dissipative piece of the gravitational self force on orbits of Kerr black holes. This calculation involves summing over a large number of harmonics. Each harmonic is independent of all others, so it is well suited to parallel computation. We show preliminary results for equatorial eccentric orbits and circular inclined orbits, demonstrating convergence of the harmonic expansion, as well as interesting phenomenology of the self force's behavior in the strong field. We conclude by discussing plans for using this force to study generic orbits, with a focus on the behavior of orbital resonances. [Preview Abstract] |
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