Bulletin of the American Physical Society
APS April Meeting 2023
Volume 68, Number 6
Minneapolis, Minnesota (Apr 15-18)
Virtual (Apr 24-26); Time Zone: Central Time
Session C09: Numerical Simulations I |
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Sponsoring Units: DGRAV Chair: Elias Most, Princeton University Room: Conrad B/C - 2nd Floor |
Saturday, April 15, 2023 1:30PM - 1:42PM |
C09.00001: BlackHoles@Home: First Gravitational Waveform Catalog Zachariah B Etienne Each observation of a gravitational wave (GW) is compared against millions of theoretical predictions to perform parameter estimation and extract important science. Our most reliable GW predictions build upon catalogs of numerical relativity (NR) compact binary coalescence simulations, which to date has always required a computing cluster. Such large computational expense has limited the catalog size to only about 3,000 in 15 years. Given the vast parameter space of even the simplest (but most commonly observed) GW source---binary black holes (BBHs)---this small GW collection threatens potential science gains from future GW observations. |
Saturday, April 15, 2023 1:42PM - 1:54PM |
C09.00002: Using SpECTRE to simulate binary-black-hole inspirals Geoffrey Lovelace Future gravitational-wave observatories, such as the Einstein Telescope, Cosmic Explorer, and LISA will measure gravitational waves with signal-to-noise ratios in the thousands. Interpreting these observations without bias will require gravitational waves with much higher accuracy. SpECTRE is a next-generation numerical-relativity code that aims to achieve this accuracy by combining Discontinuous Galerkin methods with task-based parallelism to enable scaling to many more processors than its predecessor, SpEC. In this talk, I will discuss the current status of binary-black-hole simulations with SpECTRE, including comparisons with analogous simulations using SpEC. |
Saturday, April 15, 2023 1:54PM - 2:06PM |
C09.00003: Observing the Momentum Density of Waves in Black Hole Mergers Andrea Ceja Modeling gravitational waves with supercomputer simulations allows us to compare models to detected waveforms and to check whether they are consistent with Einstein's predictions. The louder those detected signals are (i.e., the higher the signal-to-nosie ratio), the more accurate the numerical relativity model must be, because numerical errors larger than experimental errors lead to biased interpretations of gravitational-wave observations. Future detectors with higher sensitivity, such as Cosmic Explorer, Einstein Telescope, and LISA, will be much more sensitive than today’s detectors and thus will require better accuracy from numerical relativity models. SpECTRE is a next-generation numerical relativity code aiming to model gravitational waves emitted by black holes and neutron stars with much higher accuracy, by using novel techniques that scale well, to make effective use of exascale computing facilities. One physical quantity of interest that SpECTRE aims to compute is the recoil (“kick”) of the remnant. After a binary black hole merger, the momentum released through gravitational waves causes the merged black hole to experience a recoil velocity. As a first step toward computing the recoil of a binary-black-hole merger, I enabled SpECTRE to compute the momentum density for a scalar wave, a simple test case. I will present and discuss calculations of the momentum density of a scalar wave with SpECTRE. |
Saturday, April 15, 2023 2:06PM - 2:18PM |
C09.00004: Worldtube excision method for intermediate-mass-ratio inspirals: scalar-field toy model in 3+1D Nikolas Wittek, Mekhi Dhesi, Leor Barack, Harald P Pfeiffer, Adam Pound, Hannes Rüter, Marceline S Bonilla, Nils Deppe, Lawrence E Kidder, Prayush Kumar, Mark A Scheel, William T Throwe, Nils L Vu Binary black hole simulations become increasingly computationally expensive with smaller mass ratios because the Courant-Friedrich-Lewy condition imposes smaller time steps by the need to resolve the smaller black hole. Here we propose and explore a method for alleviating the scale disparity in simulations with mass ratios in the intermediate astrophysical range (10−4?q?10−2), where purely perturbative methods may not be adequate. A region much larger than the small black hole is excised from the numerical domain, and replaced with an analytical model approximating a tidally deformed black hole. We apply this idea to a toy model of a scalar charge in a circular geodesic orbit around a Schwarzschild black hole, solving for the massless Klein-Gordon field in a 3+1D framework using SpECTRE, the new discontinuous Galerkin code of the SXS collaboration. |
Saturday, April 15, 2023 2:18PM - 2:30PM |
C09.00005: Small-mass-ratio corrections to the binding energy during transition to plunge Aaron Zimmerman, Sergi Navarro Albalat, Matthew Giesler, Mark A Scheel The small-mass-ratio (SMR) approximation describes binary motion by perturbing off geodesic motion. Originally developed to describe extreme-mass-ratio inspirals, comparisons to numerical simulations have shown that this approach is remarkably successful even for binaries with comparable masses. In the past these comparisons have been limited to the adiabatic inspiral phase. Here we extend these comparisons into the transition to plunge, which can last for many gravitational wave cycles before merger. By examining the binding energy in binary black hole simulations over a range of mass ratios, we find that the systems can be described by the leading SMR prediction for transition dynamics. We extract higher-order SMR corrections and demonstrate that a combination of inspiral and transition SMR models can describe the simulations up until a half cycle before merger, even at equal mass. |
Saturday, April 15, 2023 2:30PM - 2:42PM |
C09.00006: Comparisons between numerical relativity and small mass ratio waveform models during the transition to plunge. Leanne C Durkan, Aaron Zimmerman, Lorenzo Kuchler, Geoffrey Compere, Adam Pound, Barry Wardell, Niels Warburton, Jeremy Miller, Alexandre Le Tiec, Sergi Navarro It has long been stated that in order to perform precision tests of general relativity (GR) by comparing gravitational wave (GW) models from black hole perturbation theory with observations, one must calculate the phase to the next-to-leading order in the small mass ratio (SMR) expansion. The extent to which this statement is true however needs to be tested. That is, how far can the SMR expansion be pushed towards equal mass ratios before higher-order terms become non-negligible? |
Saturday, April 15, 2023 2:42PM - 2:54PM |
C09.00007: Improving Eccentricity Reduction for Black Hole Binaries in SpEC Sarah Habib, Mark A Scheel, Saul A Teukolsky Quasi-circular compact binaries are expected to make up the majority of binaries observed by LIGO. However, given that orbital eccentricity is not well-defined in general relativity, providing initial data for such binaries is a challenge for numerical simulations. SpEC obtains initial conditions for low-eccentricity binary simulations by iterating a sequence of short simulations with decreasing eccentricity. However, the current algorithm can be very sensitive to small changes in parameters, particularly as the eccentricity gets smaller. We have developed an improved algorithm that is more robust, consistent and accurate; the primary innovation is the use of variable projection in place of conventional nonlinear optimization routines. |
Saturday, April 15, 2023 2:54PM - 3:06PM |
C09.00008: Eccentricity estimation from initial data for numerical relativity simulations Alessandro Ciarfella, James Healy, Carlos O Lousto, Hiroyuki Nakano We describe and study an instantaneous definition of eccentricity to be applied at the initial |
Saturday, April 15, 2023 3:06PM - 3:18PM |
C09.00009: The Frequency Spectra of Gravitational Waveforms with Memory in Numerical Relativity Yitian Chen, Michael Boyle, Saul A Teukolsky Gravitational wave memory effects have long been calculated using the Post-Newtonian approximation. Only recently has numerical relativity been able to produce waveforms that contain these effects. For an event detected with a large signal-to-noise ratio, the inclusion of memory in the waveform model can potentially affect the performance of parameter estimation. We examine the frequency spectra of numerical waveforms both with and without memory. We find interesting differences between their spectra in the inspiral part and in their low-frequency content. We also compare the results of Bilby parameter estimation using waveform models with and without memory. |
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