Bulletin of the American Physical Society
APS April Meeting 2016
Volume 61, Number 6
Saturday–Tuesday, April 16–19, 2016; Salt Lake City, Utah
Session E14: Numerical Relativity Simulations of Binary Mergers |
Hide Abstracts |
Sponsoring Units: GGR Chair: Geoffrey Lovelace, California State University, Fullerton Room: 251AB |
Saturday, April 16, 2016 3:30PM - 3:42PM |
E14.00001: Neutron star evolutions using the discontinuous Galerkin method Francois Hebert Relativistic hydrodynamic simulations enable us, for instance, to generate templates used for gravitational-wave detections of black hole-neutron star mergers, or to understand supernova explosion mechanisms. But the limited accuracy of the simulation algorithms used, often based on the finite volume method, constrains the insight we can obtain into these problems. We aim to improve the accuracy of our simulations by using a discontinuous Galerkin method. This method's attractiveness arises from its combination of spectral convergence properties for smooth solutions with robust stability properties for shocks. We present our work implementing a testbed discontinuous Galerkin GR-hydro code, and show our results for test evolutions of an isolated neutron star. [Preview Abstract] |
Saturday, April 16, 2016 3:42PM - 3:54PM |
E14.00002: Developing Discontinuous Galerkin Methods for Solving Multiphysics Problems in General Relativity Lawrence Kidder, Scott Field, Saul Teukolsky, Francois Foucart Multi-messenger observations of the merger of black hole-neutron star and neutron star-neutron star binaries, and of supernova explosions will probe fundamental physics inaccessible to terrestrial experiments. Modeling these systems requires a relativistic treatment of hydrodynamics, including magnetic fields, as well as neutrino transport and nuclear reactions. The accuracy, efficiency, and robustness of current codes that treat all of these problems is not sufficient to keep up with the observational needs. We are building a new numerical code that uses the Discontinuous Galerkin method with a task-based parallelization strategy, a promising combination that will allow multiphysics applications to be treated both accurately and efficiently on petascale and exascale machines. The code will scale to more than 100,000 cores for efficient exploration of the parameter space of potential sources and allowed physics, and the high-fidelity predictions needed to realize the promise of multi-messenger astronomy. I will discuss the current status of the development of this new code. [Preview Abstract] |
Saturday, April 16, 2016 3:54PM - 4:06PM |
E14.00003: Gravitational waveforms for neutron star binaries from binary black hole simulations Kevin Barkett, Mark Scheel, Roland Haas, Christian Ott, Sebastiano Bernuzzi, Duncan Brown, Bela Szilagyi, Jeffrey Kaplan, Jonas Lippuner, Curran Muhlberger, Francois Foucart, Matthew Duez Gravitational waves from binary neutron star (BNS) and black-hole/neutron star (BHNS) inspirals are primary sources for detection by the Advanced Laser Interferometer Gravitational-Wave Observatory. The tidal forces acting on the neutron stars induce changes in the phase evolution of the gravitational waveform, and these changes can be used to constrain the nuclear equation of state. Current methods of generating BNS and BHNS waveforms rely on either computationally challenging full 3D hydrodynamical simulations or approximate analytic solutions. We introduce a new method for computing inspiral waveforms for BNS/BHNS systems by adding the post-Newtonian (PN) tidal effects to full numerical simulations of binary black holes (BBHs), effectively replacing the non-tidal terms in the PN expansion with BBH results. Comparing a waveform generated with this method against a full hydrodynamical simulation of a BNS inspiral yields a phase difference of $<1$ radian over $\sim 15$ orbits. The numerical phase accuracy required of BNS simulations to measure the accuracy of the method we present here is estimated as a function of the tidal deformability parameter $\lambda$. [Preview Abstract] |
Saturday, April 16, 2016 4:06PM - 4:18PM |
E14.00004: A complete waveform model for compact binaries on eccentric orbits Eliu Huerta, Bhanu Agarwal, Daniel George, Prayush Kumar The detection of compact binaries with significant eccentricity in the sensitivity band of gravitational wave detectors will provide critical insights on the dynamics and formation channels of these events. In order to search for these systems and place constraints on their rates, we present an inspiral-merger-ringdown time domain waveform model that describes the GW emission from compact binaries on orbits with low to moderate values of eccentricity. We use this model to explore the detectability of these events in the context of advanced LIGO. [Preview Abstract] |
Saturday, April 16, 2016 4:18PM - 4:30PM |
E14.00005: Modeling Dynamical Black Holes with Spin Parameters Larger Than 0.999 Ian Ruchlin, Zachariah Etienne Exploring the extremal Kerr limit in a dynamical, fully general relativistic context may lend insights into the no-hair theorem and uncover new mechanisms by which black hole spins can be increased beyond astrophysical or Kerr limits. Modeling such black holes is highly challenging, with state-of-the-art numerical relativity simulations reaching spin parameters of 0.99 to 0.995 only recently. We have developed new techniques that open the door to stable and reliable puncture black hole evolutions with spin parameters in excess of 0.999. We briefly review these techniques, the results, and possible applications. [Preview Abstract] |
Saturday, April 16, 2016 4:30PM - 4:42PM |
E14.00006: Reduced order model for binary neutron star waveforms with tidal interactions Benjamin Lackey, Sebastiano Bernuzzi, Chad Galley Observations of inspiralling binary neutron star (BNS) systems with Advanced LIGO can be used to determine the unknown neutron-star equation of state by measuring the phase shift in the gravitational waveform due to tidal interactions. Unfortunately, this requires computationally efficient waveform models for use in parameter estimation codes that typically require $10^6$-$10^7$ sequential waveform evaluations, as well as accurate waveform models with phase errors less than 1 radian over the entire inspiral to avoid systematic errors in the measured tidal deformability. The effective one body waveform model with $\ell = 2$, 3, and 4 tidal multipole moments is currently the most accurate model for BNS systems, but takes several minutes to evaluate. We develop a reduced order model of this waveform by constructing separate orthonormal bases for the amplitude and phase evolution. We find that only 10-20 bases are needed to reconstruct any BNS waveform with a starting frequency of 10 Hz. The coefficients of these bases are found with Chebyshev interpolation over the waveform parameter space. This reduced order model has maximum errors of 0.2 radians, and results in a speedup factor of more than $10^3$, allowing parameter estimation codes to run in days to weeks rather than decades. [Preview Abstract] |
Saturday, April 16, 2016 4:42PM - 4:54PM |
E14.00007: Binary black hole simulations for surrogate modeling Daniel Hemberger Analytic or data-driven models of binary black hole coalescences are used to densely cover the full parameter space, because it is computationally infeasible to do so using numerical relativity (NR). However, these models still need input from NR, either for calibration, or because the model is agnostic to the underlying physics. We use the Spectral Einstein Code (SpEC) to provide a large number of simulations to aid the construction of a NR surrogate model in a 5-dimensional subset of the parameter space. I will present an analysis of the simulations that were used to construct the surrogate model. I will also describe the infrastructure that was needed to efficiently perform a large number of simulations across many computational resources. [Preview Abstract] |
Saturday, April 16, 2016 4:54PM - 5:06PM |
E14.00008: Robust GRMHD Evolutions of Merging Black-Hole Binaries in Magnetized Plasma Bernard Kelly, Zachariah Etienne, Bruno Giacomazzo, John Baker Black-hole binary (BHB) mergers are expected to be powerful sources of gravitational radiation at stellar and galactic scales. A typical astrophysical environment for these mergers will involve magnetized plasmas accreting onto each hole; the strong-field gravitational dynamics of the merger may churn this plasma in ways that produce characteristic electromagnetic radiation visible to high-energy EM detectors on and above the Earth. Here we return to a cutting-edge GRMHD simulation of equal-mass BHBs in a uniform plasma, originally performed with the Whisky code [Giacomazzo et al., ApJ 752:L15 (2012)]. Our new tool is the recently released IllinoisGRMHD [Etienne et al., CQG 32:175009 (2015)], a compact, highly-optimized ideal GRMHD code that meshes with the Einstein Toolkit. We establish consistency of IllinoisGRMHD results with the older Whisky results, and investigate the robustness of these results to changes in initial configuration of the BHB and the plasma magnetic field, and discuss the interpretation of the "jet-like" features seen in the Poynting flux post-merger. [Preview Abstract] |
Saturday, April 16, 2016 5:06PM - 5:18PM |
E14.00009: Optimizing spinning time-domain gravitational waveforms for Advanced LIGO data analysis Zachariah Etienne, Caleb Devine, Sean McWilliams The Spinning Effective One Body---Numerical Relativity (SEOBNR) series of gravitational wave approximants are among the best available for Advanced LIGO data analysis. Unfortunately, SEOBNR codes as they currently exist within LALSuite are generally too slow to be directly useful for standard Markov-Chain Monte Carlo-based parameter estimation (PE). Reduced-Order Models (ROMs) of SEOBNR have been developed for this purpose, but there is no known way to make ROMs of the full eight-dimensional parameter space more efficient for PE than the SEOBNR codes directly. So as a proof of principle, we have sped up the original LALSuite SEOBNRv2 approximant code, which models waveforms from aligned-spin systems, by about 280x. Our optimized code shortens the timescale for conducting PE with this approximant to months, assuming a purely serial analysis, so that even modest parallelization combined with our optimized code will make running the full PE pipeline with SEOBNR codes directly a realistic possibility. A number of our SEOBNRv2 optimizations have already been applied to SEOBNRv3, a new approximant capable of modeling sources with all eight intrinsic degrees of freedom. We anticipate that once all of our optimizations have been applied to SEOBNRv3, a similar speed-up will be achieved. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700