Bulletin of the American Physical Society
APS April Meeting 2011
Volume 56, Number 4
Saturday–Tuesday, April 30–May 3 2011; Anaheim, California
Session H12: Post-Newtonian Approximations and Alternative Theories of Gravity |
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Sponsoring Units: GGR Chair: Tanja Hinderer, California Institute of Technology Room: Royal CD |
Sunday, May 1, 2011 10:45AM - 10:57AM |
H12.00001: Post-1-Newtonian tidal effects in the gravitational waveform from binary inspirals Justin Vines, Tanja Hinderer, Eanna Flanagan The gravitational wave signal from an inspiralling binary neutron star system will contain detailed information about tidal coupling in the system, and thus, about the internal physics of the neutron stars. To extract this information will require highly accurate models for the gravitational waveform. We present here a calculation of the gravitational wave signal from a binary with quadrupolar tidal interactions which includes all post-1-Newtonian-order effects in both the conservative dynamics and wave generation. We consider stars with adiabatically induced quadrupoles moving in circular orbits, and work to linear order in the stars' quadrupole moments. We find that post-1-Newtonian corrections increase the tidal signal by approximately 20\% at gravitational wave frequencies of 400 Hz. [Preview Abstract] |
Sunday, May 1, 2011 10:57AM - 11:09AM |
H12.00002: Perturbative, post-Newtonian, and general relativistic dynamics of black hole binaries Alexandre Le Tiec The detection and analysis of the gravitational radiation from coalescing black holes binaries by the ground-based LIGO/VIRGO and spaced-based LISA observatories requires very accurate theoretical predictions, used as gravitational wave templates. The relativistic dynamics of such compact binary systems can be investigated using a variety of approximation schemes and numerical methods within general relativity: post-Newtonian expansions, black hole perturbation theory, numerical relativity, and the effective-one-body formalism. We shall review the recent work at the multiple interfaces of all these analytical and numerical methods, emphasizing the use of coordinate invariant relations to perform meaningful comparisons. Such comparisons are crucial for several reasons: they provide independant consistency checks of the validity of the various calculations, they help to delineate the respective domains of validity of each method, and ultimately to improve the modelling of black hole binaries. [Preview Abstract] |
Sunday, May 1, 2011 11:09AM - 11:21AM |
H12.00003: A Hybrid Method for Inspiralling Black-Hole Binaries Yanbei Chen, David Nichols We adapt a method of matching post-Newtonian and black-hole-perturbation theories on a time-like region (which proved useful for understanding head-on black-hole binary collisions) to treat equal-mass, inspiralling black-hole binaries. We first introduce a procedure to calculate a radiation-reaction potential within our method. This allows us to produce a full inspiral-merger-ringdown waveform of the l=2, m=2 mode of the gravitational waveform of an equal-mass black-hole-binary inspiral. This mode qualitatively matches that of numerical-relativity simulations. We then consider a merger of black holes with anti-aligned spins in the orbital plane (the ``superkick'' configuration). Since the superkick arises from the fact that the mass- and current-quadrupole radiation evolves in phase during the merger and ringdown (when the quasinormal modes have the same frequency), we provide a mechanism within the near-zone of the binary that gives rise to this effect. We show that if the spins of the black holes evolve via geodetic precession in the perturbed black-hole spacetime of our model, then the spins precess at the orbital frequency during merger. In turn, this gives rise to the correct behavior of the radiation and produces a kick similar to that in numerical simulations. [Preview Abstract] |
Sunday, May 1, 2011 11:21AM - 11:33AM |
H12.00004: Inspiralling compact binaries in scalar-tensor theories of gravity: Equations of motion to 2.5 post-Newtonian order Saeed Mirshekari, Nicolas Yunes, Clifford Will Gravitational waves from inspiralling compact binaries will provide tests of alternative theories of gravity, such as the general class of scalar-tensor theories. We derive the scalar-tensor equations of motion for non-spinning compact objects, including black holes and neutron stars, to order $(v/c)^5$ beyond Newtonian order. We use the DIRE (Direct Integration of the Relaxed Einstein Equations) formalism [1] adapted to scalar- tensor theory, coupled with Eardley's scheme [2] for incorporating compact, quasi- stationary, self-gravitating bodies. Preliminary results will be reported. Supported in part by the NSF, PHY 06-52448 and 09-65133.\\[4pt] [1] A. G. Wiseman and C. M. Will, Phys. Rev. D 54, 4813 (1996); M. E. Pati and C. M. Will, Phys. Rev. D 62, 124015 (2000); ibid. 65, 104008 (2002).\\[0pt] [2] D. M. Eardley, Astrophys. J. Lett. 196, L59 (1975). [Preview Abstract] |
Sunday, May 1, 2011 11:33AM - 11:45AM |
H12.00005: Effective Gravitational Wave Stress-energy Tensor in Alternative Theories of Gravity Leo Stein The inspiral of binary systems in vacuum is controlled by the rate of change of the system's energy and angular momentum. In alternative theories, such a change is induced by the effective stress-energy carried away by gravitational radiation and any other propagating degrees of freedom. We employ perturbation theory and the short- wavelength approximation to compute this stress-energy tensor in a wide class of alternative theories. This tensor is generally a modification of that first computed by Isaacson, where the corrections can dominate over the general relativistic term. In a wide class of theories, however, these corrections identically vanish at asymptotically flat, future, null infinity, reducing the stress-energy tensor to Isaacson's. We consider a wide class of theories with dynamical scalar fields coupled to higher-order curvature invariants, and show that the gravitational wave stress-energy tensor still reduces to Isaacson's. [Preview Abstract] |
Sunday, May 1, 2011 11:45AM - 11:57AM |
H12.00006: Effective Field Theories for Dark Energy Jolyon Bloomfield, Eanna Flanagan Recent attempts have been made to derive the most general effective theory of dark energy involving gravity and a scalar field, including up to four derivatives of the fields. The resulting effective field theory incorporates a number of different models, including quintessence, k-essence, and ghost condensation. However, the derivation of these effective theories neglect issues related to the choice of frame and the coupling between the scalar field and gravity. Taking these issues into consideration, we propose a slightly different construction for and discuss the implications of the resulting effective theory. [Preview Abstract] |
Sunday, May 1, 2011 11:57AM - 12:09PM |
H12.00007: Observational Signatures of Binary Black Holes Mergers in Brans-Dicke Theory of Gravity James Healy, Pablo Laguna, Enrique Pazos, Deirdre Shoemaker, Nicolas Yunes Gravitational wave observations can be used to probe non-linear gravitational interactions and thus provide strong tests of Einstein's theory of general relativity. Using the tools of numerical relativity, we present results from the late inspiral and merger of a binary black hole system in Jordan-Brans-Dicke-Fierz theory. In particular, we address whether in this theory the gravitational waves produced during the coalescence differ from those from general relativity. We discuss how future gravitational wave observations of binary black hole mergers could be used to place bounds on such scalar-tensor theories. [Preview Abstract] |
Sunday, May 1, 2011 12:09PM - 12:21PM |
H12.00008: Topologically Massive Gravity from the Outside In Colin Cunliff The asymptotic solutions of cosmological topologically massive gravity (CTMG) are analyzed for values of the mass parameter in the range $\mu \geq 1$. At non-chiral values, a new term in the Fefferman-Graham expansion is needed to capture the bulk degree of freedom. The CDWW modes provide a basis for the pure non-Einstein solutions at all $\mu$, with nonlinear corrections appearing at higher order in the expansion. The solutions at all values of the mass parameter, including the chiral point, share the same structure, indicating that the previously accepted view -- that CTMG at generic $\mu$ is unstable, while chiral gravity at $\mu=1$ is stable -- is no longer tenable. Instead, the question of stability must be answered for CTMG as a whole. [Preview Abstract] |
Sunday, May 1, 2011 12:21PM - 12:33PM |
H12.00009: Eternal radiation and De Sitter space Douglas Singleton, Emil Akhmedov, Pavle Buividovich We give general arguments that any interacting non-conformal classical field theory in de Sitter space leads classical radiation without end. The arguments are based on the observation that massive free falling particles can radiate other massive particles on the classical level as seen by the free falling observer. The intensity of the radiation process is non-zero even for particles with any finite mass, i.e. with a wavelength which is within the causal domain. This is a reductio ad adsurdum intended to show that de Sitter space can not exist eternally. Otherwise one could extract radiation externally. [Preview Abstract] |
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