Bulletin of the American Physical Society
APS April Meeting 2014
Volume 59, Number 5
Saturday–Tuesday, April 5–8, 2014; Savannah, Georgia
Session M15: Numerical Relativity in Vacuum: Methods and Simulations II |
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Chair: Roseanne Cheng, Georgia Institute of Technology Room: 103 |
Sunday, April 6, 2014 3:30PM - 3:42PM |
M15.00001: Numerical Relativity in Spherical Polar Coordinates Thomas Baumgarte Spherical polar coordinates have many desirable properties for simulations in relativistic astrophysics. In the absence of symmetry conditions, however, numerical relativity simulations in spherical polar coordinates have been hampered by problems associated with the coordinate singularities. In this talk I will discuss a new approach that does not require regularization of the singular terms, and instead employs a reference-metric formulation of the BSSN equations, a proper rescaling of the dynamical variables, and a partially-implicit Runge-Kutta integration scheme. I will briefly review these ingredients, and will then present some tests and early applications. [Preview Abstract] |
Sunday, April 6, 2014 3:42PM - 3:54PM |
M15.00002: Modeling large remnant kicks for the mergers of unequal mass black hole binaries Yosef Zlochower, Carlos Lousto Recoils from the mergers of supermassive black hole binaries can be large enough to eject the remnant black hole out of the host galaxy. The actual recoil will depend on the size and orientation of the black-hole spins and the mass ratio of the binary. Here we discuss how relatively few simulations can be used to model the recoil for astrophysically interesting mass ratios, spin magnitudes, and spin orientations. [Preview Abstract] |
Sunday, April 6, 2014 3:54PM - 4:06PM |
M15.00003: On the dynamics of spinning binary black holes and some astrophysical consequences Carlos Lousto, Manuela Campanelli, James Healy, Ian Ruchlin, Yosef Zlochower We numerically study the final inspiral orbital dynamics of highly spinning binary black holes. In particular the effects of precession on the total radiated gravitational energy, angular and linear momentum. We discuss the main astrophysical and observational consequences of the spin dynamics and recoils when the black hole binary is immersed in gaseous environment. [Preview Abstract] |
Sunday, April 6, 2014 4:06PM - 4:18PM |
M15.00004: The Final Spin of a Binary Black-Hole System Karan Jani, Deirdre Shoemaker The coalescence of a binary black-hole (BBH) results in a space-time described by the Lorentz boosted Kerr metric. The final BH thus purely lies in a 7-dimensional parameter space consisting of the mass, spin and recoil velocity . The initial BBH system however, even in the regime of being a quasi-circular orbit, is described by 14 parameters, namely the two masses, their spins and their momenta. As a one-one map between the initial and final parameter space cannot exist, several attempts have been made in the past to provide an analytical formula that maps a set of initial binary BH parameters to a given value of final mass and final spin. In this study, we test the validity of the most used analytical spin formula listed in Barausse {\&} Rezzolla (2009) using the extensive, 484 simulations of generic BBH configurations, catalog from the Georgia Tech Numerical Relativity group. [Preview Abstract] |
Sunday, April 6, 2014 4:18PM - 4:30PM |
M15.00005: Modeling the Richness of Ringdown: From Spheroidal Decomposition to Beyond the Fundamental and First Order Quasinormal Modes Lionel London, James Healy, Deirdre Shoemaker Numerical relativity waveforms are traditionally decomposed into the orthogonal spin -2 spherical multipoles. The ringdown of black holes, however, is more naturally described by the non-orthogonal spin -2 spheroidal multipoles. As a consequence, numerical relativity ringdown waveforms consist of a superposition of spheroidal modes. Upon implementing a method that identifies the spheroidal multipole content in numerical relativity waveforms, we find not only the fundamental QNM amplitudes, but also overtones, and long lived 2nd order QNMs in a series of unequal-mass systems. We use a Post-Newtonian inspired model to present new fitting formulas for the related QNM excitations. Finally, we discuss the relevance of our results to advanced gravitational wave detectors by considering the SNR of ringdown only temples in an example scenario. [Preview Abstract] |
Sunday, April 6, 2014 4:30PM - 4:42PM |
M15.00006: Scattering of force-free electrodynamic waves by spacetime curvature Fan Zhang, Sean McWilliams The electromagnetic fields E and B are vectors that couple to spacetime curvatures via Ricci identities, and so force-free electrodynamic waves will in general be scattered. However, Brennan, Gralla and Jacobson found a family of exact solutions that escape scattering. We analytically and numerically study these solutions and their alterations, in order to provide more details as to what features allow them to possess this property. We hope our results will be useful when searching for other solutions of this type. We also provide physical intuition for some commonly encountered theoretical constructs. [Preview Abstract] |
Sunday, April 6, 2014 4:42PM - 4:54PM |
M15.00007: Black Hole Superradiance Frans Pretorius, William East, Fethi Ramazanoglu I will present results from a numerical study of the superradiant scattering of gravitational waves by a nearly extremal black hole. The full vacuum Einstein equations are solved, thus allowing us to study the back-reaction of the interaction on the black hole, and confirming that the amplification of the wave is balanced by energy and angular momentum loss of the black hole. To explore the nonlinear phase of the interaction we consider gravitational wave packets with initial energies up to 10 percent that of the mass of the black hole. We find that as the incident wave energy increases, the amplification of the scattered waves, as well as the energy extraction efficiency from the black hole, is reduced. During the interaction the apparent horizon geometry undergoes sizable non-axisymmetric oscillations. The largest amplitude excitations occur when the peak frequency of the incident wave packet is above where superradiance occurs, but close to the dominant quasi-normal mode frequency of the black hole. [Preview Abstract] |
Sunday, April 6, 2014 4:54PM - 5:06PM |
M15.00008: Chaos in the general relativistic three-body problem David Neilsen, Jared Jay, Taylor Morgan The three-body problem in classical gravity is known to have chaotic solutions. We are investigating chaos in the three-body problem in general relativity using post Newtonian equations. We model a binary system that interacts with an incoming star. We solve the post-Newtonian evolution equations in the Hamiltonian formalism to order 2.5. We present results of these interactions that display features of chaos, such as sensitivity to initial conditions and scale invariance. [Preview Abstract] |
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