Bulletin of the American Physical Society
APS April Meeting 2017
Volume 62, Number 1
Saturday–Tuesday, January 28–31, 2017; Washington, DC
Session C5: Numerical Relativity Codes and Methods |
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Sponsoring Units: DGRAV Chair: Steven Liebling, Long Island University Room: Virginia B |
Saturday, January 28, 2017 1:30PM - 1:42PM |
C5.00001: SENR: A Next-Generation, Super-Efficient Numerical Relativity Code for the Age of Gravitational Wave Astrophysics Zachariah Etienne, Ian Ruchlin, Thomas Baumgarte Short-inspiral black hole binary (BHB) mergers are perhaps the most extensively studied LIGO source candidate by numerical relativity (NR), so it was extremely fortuitous that LIGO’s first detections of gravitational waves (GWs) were from precisely these systems. In a sense, these discoveries represent coming-of-age for our field, but NR’s current position is a precarious one. LIGO data analysis depends on NR-based GW catalogs built upon only one NR code and remain largely unvalidated by independent NR codes. More worryingly, LIGO may soon detect GWs from a double neutron star (DNS) binary, and there currently exist no NR codes capable of generating DNS GWs with small, convergent phase errors over large numbers of orbits in-band. We introduce SENR, a Super-Efficient, open-development NR code aimed at addressing these critical shortcomings. Building upon recent breakthroughs in reference metric-based simulations, SENR employs dynamical coordinate systems to increase the efficiency of moving-puncture BHB and DNS GW modeling by ~100x. Excitingly, SENR has the potential to afford high-end gamers the opportunity to join us in source modeling, potentially increasing throughput of GW generation by an enormous factor. We present an overview of the SENR code and its development. [Preview Abstract] |
Saturday, January 28, 2017 1:42PM - 1:54PM |
C5.00002: SENR, A Super-Efficient Code for Gravitational Wave Source Modeling: Latest Results Ian Ruchlin, Zachariah Etienne, Thomas Baumgarte The science we extract from gravitational wave observations will be limited by our theoretical understanding, so with the recent breakthroughs by LIGO, reliable gravitational wave source modeling has never been more critical. Due to efficiency considerations, current numerical relativity codes are very limited in their applicability to direct LIGO source modeling, so it is important to develop new strategies for making our codes more efficient. We introduce SENR, a Super-Efficient, open-development numerical relativity (NR) code aimed at improving the efficiency of moving-puncture-based LIGO gravitational wave source modeling by ~100x. SENR builds upon recent work, in which the BSSN equations are evolved in static spherical coordinates, to allow dynamical coordinates with arbitrary spatial distributions. The physical domain is mapped to a uniform-resolution grid on which derivative operations are approximated using standard central finite difference stencils. The source code is designed to be human-readable, efficient, parallelized, and readily extensible. We present the latest results from the SENR code. [Preview Abstract] |
Saturday, January 28, 2017 1:54PM - 2:06PM |
C5.00003: A Parallel Wavelet Approach for Binary Compact Object Mergers Hyun Lim, Eric Hirschmann, David Neilsen, William Black, Matthew Anderson, Hari Sundar, Milinda Fernando Highly accurate simulations of binary black holes and neutron stars are needed to address a variety of interesting problems in relativistic astrophysics. We report on an ongoing development effort to solve the Einstein equations using iterated interpolating wavelets.~Wavelet coefficients provide a direct measure of the local approximation error for a solution and place collocation points that naturally adapt to features of the solution. Further, they exhibit good convergence properties on unevenly spaced collocation points. ~These are readily incorporated into a parallel implementation using DENDRO, a highly scalable parallel algorithm for multigrid and AMR methods on 2:1 balanced octrees. [Preview Abstract] |
Saturday, January 28, 2017 2:06PM - 2:18PM |
C5.00004: General Relativistic Smoothed Particle Hydrodynamics code developments: A progress report Joshua Faber, Zachary Silberman, Monica Rizzo We report on our progress in developing a new general relativistic Smoothed Particle Hydrodynamics (SPH) code, which will be appropriate for studying the properties of accretion disks around black holes as well as compact object binary mergers and their ejecta. We will discuss in turn the relativistic formalisms being used to handle the evolution, our techniques for dealing with conservative and primitive variables, as well as those used to ensure proper conservation of various physical quantities. Code tests and performance metrics will be discussed, as will the prospects for including smoothed particle hydrodynamics codes within other numerical relativity codebases, particularly the publicly available Einstein Toolkit. [Preview Abstract] |
Saturday, January 28, 2017 2:18PM - 2:30PM |
C5.00005: Solving Einstein's Equation Numerically on Manifolds with Arbitrary Topologie Lee Lindblom This talk will summarize some of the numerical methods we have developed for solving Einstein's equation numerically on manifolds with arbitrary spatial topologies. These methods include the use of multi-cube representations of arbitrary manifolds, a convenient new way to specify the differential structure on multi-cube representations, and a new fully covariant first-order symmetric hyperbolic representation of Einstein's equation. Progress on the problem of constructing the "reference metrics" (which are an essential element of our numerical method) for arbitrary manifolds will be described, and numerical results will be presented for some example simulations. [Preview Abstract] |
Saturday, January 28, 2017 2:30PM - 2:42PM |
C5.00006: Vector Potential Generation for Numerical Relativity Simulations Zachary Silberman, Joshua Faber, Thomas Adams, Zachariah Etienne, Ian Ruchlin Many different numerical codes are employed in studies of highly relativistic magnetized accretion flows around black holes. Based on the formalisms each uses, some codes evolve the magnetic field vector B, while others evolve the magnetic vector potential A, the two being related by the curl: B=curl(A). Here, we discuss how to generate vector potentials corresponding to specified magnetic fields on staggered grids, a surprisingly difficult task on finite cubic domains. The code we have developed solves this problem in two ways: a brute-force method, whose scaling is nearly linear in the number of grid cells, and a direct linear algebra approach. We discuss the success both algorithms have in generating smooth vector potential configurations and how both may be extended to more complicated cases involving multiple mesh-refinement levels. [Preview Abstract] |
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