Bulletin of the American Physical Society
APS April Meeting 2017
Volume 62, Number 1
Saturday–Tuesday, January 28–31, 2017; Washington, DC
Session K3: Numerical Relativity Solutions for Black Hole Binaries |
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Sponsoring Units: DGRAV Chair: Bruno Giacomazzo, University of Trento Room: Maryland C |
Sunday, January 29, 2017 1:30PM - 1:42PM |
K3.00001: Visualization of a Numerical Simulation of GW 150914 Nicole Rosato, James Healy, Carlos Lousto We present an analysis of a simulation displaying apparent horizon curvature and radiation emitted from a binary black hole system modeling GW-150914 during merger. The simulation follows the system from seven orbits prior to merger to the resultant Kerr black hole. Horizon curvature was calculated using a mean curvature flow algorithm. Radiation data was visualized via the $\Psi_4$ component of the Weyl scalars, which were determined using a numerical quasi-Kinnersley method. We also present a comparative study of the differences in quasi-Kinnersley and PsiKadelia tetrads to construct $\Psi_4$. The analysis is displayed on a movie generated from these numerical results, and was done using VisIt software from Lawrence Livermore National Laboratory. This simulation and analysis gives more insight into the merger of the system GW 150914. [Preview Abstract] |
Sunday, January 29, 2017 1:42PM - 1:54PM |
K3.00002: Surrogate models of gravitational waveforms from numerical relativity simulations of precessing binary black hole mergers Jonathan Blackman, Scott Field, Chad Galley, Daniel Hemberger, Mark Scheel, Patricia Schmidt, Rory Smith Extracting astrophysical parameters and testing general relativity from gravitational wave observations of binary black hole mergers requires high-fidelity signal predictions. The effective-one-body model and phenomenological waveform models have been shown to work well for a subset of the possible parameter space. They could be insufficiently accurate for estimating the parameters of a loud gravitational wave detection in other regions of the parameter space. Numerical relativity (NR) surrogate models attempt to rapidly and accurately interpolate the waveforms from a set of NR simulations over a subset of parameter space. Using the Spectral Einstein Code (SpEC), we have built NR surrogate models for precessing binaries with a restricted spin direction on the smaller black hole, and are actively working on extending this to the full 7d parameter space of non-eccentric binaries. The NR surrogate models typically perform an order of magnitude better than other waveform models when compared to NR waveforms which were not included in the surrogate training set, and can be used in gravitational wave parameter estimation. [Preview Abstract] |
Sunday, January 29, 2017 1:54PM - 2:06PM |
K3.00003: New Initial Data with Trumpet Time Slices for Highly Boosted Black Holes Kyle Slinker, Charles Evans, Mark Hannam We show a new method for constructing numerical relativity initial data for moving black holes with high Lorentz factor. For a single black hole, this data is constructed through a sequence of coordinate changes applied to Schwarzschild spacetime. It therefore, by construction, analytically solves the constraint equations and contains virtually no junk gravitational radiation beyond discretization errors. The initial time slice has trumpet topology closely adapted to the 1+log gauge condition, which the moving punctures gauge conditions rapidly drive to a stationary state. Compared with Bowen-York initial data, our data contains several orders of magnitude less junk radiation and yields a smooth initialization of black hole evolutions with Lorentz factors up to 2 or more. [Preview Abstract] |
Sunday, January 29, 2017 2:06PM - 2:18PM |
K3.00004: Computing Binary Black Hole Initial Data in Damped Harmonic Gauge Vijay Varma, Mark Scheel Binary black hole evolution in the Spectral Einstein Code (SpEC) is currently done in the damped harmonic (DH) gauge, which has proven very useful for merger simulations. However, the initial data for the simulation is constructed in a different gauge. Once the evolution starts we need to perform a smooth gauge transformation to the DH gauge, introducing additional gauge dynamics into the evolution. In this work, we construct the initial data in the DH gauge itself, which allows us to avoid the above gauge transformation. This can have added benefits such as possibly reducing junk radiation, making it easier to achieve a desired orbital eccentricity, reducing the runtime of simulations, and being able to start evolution closer to the merger. [Preview Abstract] |
Sunday, January 29, 2017 2:18PM - 2:30PM |
K3.00005: Puncture-Based Evolutions of Highly Spinning Black-Hole Binaries Yosef Zlochower, Carlos Lousto, James Healy, Ian Ruchlin We recently developed a code for solving the 3+1 system of constraints for highly-spinning black-hole binary initial data in the puncture formalism. Here we explore how different choices of gauge can be used to efficiently evolve binaries with near maximal spins. [Preview Abstract] |
Sunday, January 29, 2017 2:30PM - 2:42PM |
K3.00006: Numerical Relativity and the Bondi-Metzner-Sachs Group Jeffrey Winicour There are interesting phenomena associated with the Bondi-Metzner-Sachs (BMS) group that deserve numerical exploration. The BMS group, which is the asymptotic symmetry group of an isolated gravitational system, extends the Poincare group by the addition of an infinite set of supertranslations parameterized by a function on the sphere $\alpha(\theta,\phi)$. The $\ell=0$ and $\ell=1$ spherical harmonics invariantly pick out the time and space translations, which leads to an unambiguous definition of energy and momentum. However, a Poincare subgroup cannot be invariantly defined, which leads to a supertranslation ambiguity in the definition of angular momentum. This opens the possibility of a purely general relativistic mechanism for angular momentum loss. The supertranslations are also associated with the gravitational memory effect. I will discuss these problems which are ripe for the numerical simulation of high spin black hole binaries. [Preview Abstract] |
Sunday, January 29, 2017 2:42PM - 2:54PM |
K3.00007: Black hole mergers: beyond general relativity Leo Stein, Maria Okounkova One hundred years after the birth of general relativity, advanced LIGO has finally directly detected gravitational waves. The source: two black holes merging into one. Advanced LIGO will soon provide the opportunity to test GR, using gravitational waves, in the dynamical strong-field regime---a setting where GR has not yet been tested. GR has passed all weak-field tests with flying colors. Yet it should eventually break down, so we must look to the strong-field. To perform strong-field tests of GR, we need waveform models from theories \emph{beyond} GR. To date there are no numerical simulations of black hole mergers in theories which differ from GR. The main obstacle is the mathematical one of well-posedness. I will explain how to overcome this obstacle, and demonstrate the success of this approach by presenting the first numerical simulations of black hole mergers in a theory beyond GR. [Preview Abstract] |
Sunday, January 29, 2017 2:54PM - 3:06PM |
K3.00008: Binary compact object mergers in Einstein-Maxwell-Dilaton theories Eric Hirschmann, Luis Lehner, Steve Liebling, Carlos Palenzuela We present work on the dynamics and gravitational wae emission of binary black holes in a modified theory of gravity. Our particular model is inspired by low energy string theory and includes additional matter fields, such as a dilaton, not necessarily present in vacuum general relativity. We consider deviations from standard predictions for gravitational wave signatures and examine alternative scalar and electromagnetic channels for emission. [Preview Abstract] |
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