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Impact of subdominant modes on the interpretation of gravitational-wave signals from heavy binary black hole systems

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Physical Review D 2020年第12期101卷 124054-124054页

作者： Feroz H. Shaik Jacob Lange Scott E. Field Richard O’Shaughnessy Vijay Varma Lawrence E. Kidder Harald P. Pfeiffer Daniel Wysocki Department of Physics Department of Mathematics and the Center for Scientific Computing & Visualization Research University of Massachusetts Dartmouth Dartmouth Massachusetts 02747 USA Center for Computational Relativity and Gravitation Rochester Institute of Technology Rochester New York 14623 USA Department of Mathematics and the Center for Scientific Computing & Visualization Research University of Massachusetts Dartmouth Dartmouth Massachusetts 02747 USA Theoretical Astrophysics California Institute of Technology Pasadena California 91125 USA Cornell Center for Astrophysics and Planetary Science Cornell University Ithaca New York 14853 USA Max Planck Institute for Gravitational Physics (Albert Einstein Institute) Am Mühlenberg 1 14476 Potsdam Germany

Over the past year, a handful of new gravitational wave models have been developed to include multiple harmonic modes thereby enabling for the first time fully Bayesian inference studies including higher modes to be performed. Using one recently developed numerical relativity surrogate model, NRHybSur3dq8, we investigate the importance of higher modes on parameter inference of coalescing massive binary black holes. We focus on examples relevant to the current three-detector network of observatories, with a detector-frame mass set to 120 M⊙ and with signal amplitude values that are consistent with plausible candidates for the next few observing runs. We show that for such systems the higher mode content will be important for interpreting coalescing binary black holes, reducing systematic bias, and computing properties of the remnant object. Even for comparable-mass binaries and at low signal amplitude, the omission of higher modes can influence posterior probability distributions. We discuss the impact of our results on source population inference and self-consistency tests of general relativity. Our work can be used to better understand asymmetric binary black hole merger events, such as GW190412. Higher modes are critical for such systems, and their omission usually produces substantial parameter biases.

关键词： Gravitational waves

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A Review of Three-Dimensional Medical Image visualization

健康数据科学（英文）

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健康数据科学（英文） 2022年第3期 53-71页

作者： Liang Zhou Mengjie Fan Charles Hansen Chris R.Johnson Daniel Weiskopf National Institute of Health Data Science Peking UniversityBeijingChina Scientific Computing and Imaging Institute University of UtahSalt Lake CityUSA Visualization Research Center(VISUS) University of StuttgartStuttgartGermany

*** images are essential for modern medicine and an important research subject in ***,medical experts are often not aware of the many advanced three-dimensional(3D)medical image visualization techniques that could increase their capabilities in data analysis and assist the decision-making process for specific medical *** paper provides a review of 3D visualization techniques for medical images,intending to bridge the gap between medical experts and visualization *** visualization techniques are revisited for various medical imaging modalities,from computational tomography to diffusion tensor imaging,featuring techniques that enhance spatial perception,which is critical for medical *** state-of-the-art of medical visualization is reviewed based on a procedure-oriented classification of medical problems for studies of individuals and *** paper summarizes free software tools for different modalities of medical images designed for various purposes,including visualization,analysis,and segmentation,and it provides respective Internet *** techniques are a useful tool for medical experts to tackle specific medical problems in their daily *** review provides a quick reference to such techniques given the medical problem and modalities of associated medical *** summarize fundamental techniques and readily available visualization tools to help medical experts to better understand and utilize medical imaging *** paper could contribute to the joint effort of the medical and visualization communities to advance precision medicine.

关键词： review image dimensional medical three visualization

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Gravitational tuning forks and hierarchical triple systems

arXiv

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arXiv 2021年

作者： Cardoso, Vitor Duque, Francisco Khanna, Gaurav CENTRA Departamento de Física Instituto Superior Técnico – IST Universidade de Lisboa – UL Avenida Rovisco Pais 1 Lisboa1049 Portugal Department of Physics Center for Scientific Computing and Visualization Research University of Massachusetts DarthmouthMA02747 United States Department of Physics University of Rhode Island KingstonRI02881 United States

We study gravitational wave (GW) emission in the strong-field regime by a hierarchical triple system composed of a binary system placed in the vicinity of a supermassive black hole (SMBH). The LIGO-Virgo collaboration recently reported evidence for coalescences with this dynamical origin. These systems are common in galactic centers and thus are a target for the space-based LISA mission as well as other advanced detectors. Doppler shifts, aberration, lensing and strong amplitude modulations are features present in the GW signal from these systems, built into our framework and with no need for phenomenological patches. We find that the binary can resonantly excite the quasinormal modes of the SMBH, as in the resonant excitation of two tuning forks with matching frequencies. The flux of energy crossing the SMBH horizon can be significant, when compared with that from standard extreme-mass-ratio inspirals. Therefore, these triple systems are excellent probes of strong-field physics and of the BH nature of compact objects. © 2021, CC BY.

关键词： Hierarchical systems

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Vortex criteria can be objectivized by unsteadiness minimization

arXiv

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arXiv 2021年

作者： Theisel, Holger Hadwiger, Markus Rautek, Peter Theußl, Thomas Günther, Tobias Department of Computer Science Otto-von-Guericke University of Magdeburg Magdeburg Germany Visual Computing Center King Abdullah University of Science and Technology Thuwal23955-6900 Saudi Arabia Visualization Core Lab King Abdullah University of Science and Technology Thuwal23955-6900 Saudi Arabia Department of Computer Science Friedrich-Alexander-University of Erlangen-Nuremberg Erlangen Germany

Reference frame optimization is a generic framework to calculate a spatially-varying observer field that views an unsteady fluid flow in a reference frame that is as-steady-as-possible. In this paper, we show that the optimized vector field is objective, i.e., it is independent of the initial Euclidean transformation of the observer. To check objectivity, the optimized velocity vectors and the coordinates in which they are defined must both be connected by an Euclidean transformation. In this paper we show that a recent publication [1] applied this definition incorrectly, falsely concluding that reference frame optimizations are not objective. Further, we prove the objectivity of the variational formulation of the reference frame optimization proposed in [1], and discuss how the variational formulation relates to recent local and global optimization approaches to unsteadiness minimization. © 2021, CC BY.

关键词： Global optimization

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Surrogate model for gravitational wave signals from nonspinning, comparable-to large-mass-ratio black hole binaries built on black hole perturbation theory waveforms calibrated to numerical relativity

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Physical Review D 2022年第10期106卷 104025-104025页

作者： Tousif Islam Scott E. Field Scott A. Hughes Gaurav Khanna Vijay Varma Matthew Giesler Mark A. Scheel Lawrence E. Kidder Harald P. Pfeiffer Department of Physics University of Massachusetts Dartmouth Massachusetts 02747 USA Department of Mathematics University of Massachusetts Dartmouth Massachusetts 02747 USA Center for Scientific Computing and Visualization Research University of Massachusetts Dartmouth Massachusetts 02747 USA Kavli Institute of Theoretical Physics University of California Santa Barbara Santa Barbara California 93106 USA Department of Physics and MIT Kavli Institute Massachusetts Institute of Technology Cambridge Massachusetts 02139 USA Department of Physics University of Rhode Island Kingston Rhode Island 02881 USA Max Planck Institute for Gravitational Physics (Albert Einstein Institute) Am Mühlenberg 1 Potsdam 14476 Germany Cornell Center for Astrophysics and Planetary Science Cornell University Ithaca New York 14853 USA Theoretical Astrophysics Walter Burke Institute for Theoretical Physics California Institute of Technology Pasadena California 91125 USA

We present a reduced-order surrogate model of gravitational waveforms from nonspinning binary black hole systems with comparable to large mass-ratio configurations. This surrogate model, BHPTNRSur1dq1e4, is trained on waveform data generated by point-particle black hole perturbation theory (ppBHPT) with mass ratios varying from 2.5 to 10,000. BHPTNRSur1dq1e4 extends an earlier waveform model, EMRISur1dq1e4, by using an updated transition-to-plunge model, covering longer durations up to 30,500m1 (where m1 is the mass of the primary black hole), includes several more spherical harmonic modes up to ℓ=10, and calibrates subdominant modes to numerical relativity (NR) data. In the comparable mass-ratio regime, including mass ratios as low as 2.5, the gravitational waveforms generated through ppBHPT agree surprisingly well with those from NR after this simple calibration step. We also compare our model to recent SXS and RIT NR simulations at mass ratios ranging from 15 to 32, and find the dominant quadrupolar modes agree to better than ≈10−3. We expect our model to be useful to study intermediate-mass-ratio binary systems in current and future gravitational-wave detectors.

关键词： Gravitational waves

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Overcoming limitations of GPGPU-computing in scientific applications

arXiv

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arXiv 2019年

作者： Kenyon, Connor Volkema, Glenn Khanna, Gaurav Physics Department Center for Scientific Computing and Visualization University of Massachusetts Dartmouth North DartmouthMA02747 United States

The performance of discrete general purpose graphics processing units (GPGPUs) has been improving at a rapid pace. The PCIe interconnect that controls the communication of data between the system host memory and the GPU has not improved as quickly, leaving a gap in performance due to GPU downtime while waiting for PCIe data transfer. In this article, we explore two alternatives to the limited PCIe bandwidth, NVIDIA NVLink interconnect, and zero-copy algorithms for shared memory Heterogeneous System Architecture (HSA) devices. The OpenCL SHOC benchmark suite is used to measure the performance of each device on various scientific application kernels. Copyright © 2019, The Authors. All rights reserved.

关键词： Graphics processing unit

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Basis Function Method for Numerical Loop Quantum Cosmology: The Schwarzschild Black Hole Interior

arXiv

引用

arXiv 2019年

作者： Yonika, Alec Khanna, Gaurav Department of Physics & Center for Scientific Computing and Visualization Research University of Massachusetts Dartmouth North DartmouthMA02747 United States

Loop quantum cosmology is a symmetry-reduced application of loop quantum gravity that has led to the resolution of classical singularities such as the big bang, and those at the center of black holes. This can be seen through numerical simulations involving the quantum Hamiltonian constraint that is a partial difference equation. The equation allows one to study the evolution of sharply-peaked Gaussian wave packets that generically exhibit a quantum "bounce" or a non-singular passage through the classical singularity, thus offering complete singularity resolution. In addition, von-Neumann stability analysis of the difference equation – treated as a stencil for a numerical solution that steps through the triad variables – yields useful constraints on the model and the allowed space of states. In this paper, we develop a new method for the numerical solution of loop quantum cosmology models using a set of basis functions that offer a number of advantages over computing a solution by stepping through the triad variables. We use the Corichi and Singh model for the Schwarzschild interior as the main case study in this effort. The main advantage of this new method is computational efficiency and the ease of parallelization. In addition, we also discuss how the stability analysis appears in the context of this new approach. Copyright © 2019, The Authors. All rights reserved.

关键词： Gravitation

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A surrogate model for gravitational wave signals from comparable- to large-mass-ratio black hole binaries

arXiv

引用

arXiv 2019年

作者： Rifat, Nur E.M. Field, Scott E. Khanna, Gaurav Varma, Vijay Department of Physics and Center for Scientific Computing & Visualization Research University of Massachusetts DartmouthMA02747 United States Department of Mathematics Center for Scientific Computing & Visualization Research University of Massachusetts DartmouthMA02747 United States Theoretical Astrophysics California Institute of Technology PasadenaCA91125 United States

Gravitational wave signals from compact astrophysical sources such as those observed by LIGO and Virgo require a high-accuracy, theory-based waveform model for the analysis of the recorded signal. Current inspiral-merger-ringdown models are calibrated only up to moderate mass ratios, thereby limiting their applicability to signals from high-mass ratio binary systems. We present EMRISur1dq1e4, a reduced-order surrogate model for gravitational waveforms of 13, 500M in duration and including several harmonic modes for non-spinning black hole binary systems with mass-ratios varying from 3 to 10, 000 thus vastly expanding the parameter range beyond the current models. This surrogate model is trained on waveform data generated by point-particle black hole perturbation theory (ppBHPT) both for large mass-ratio and comparable mass-ratio binaries. We observe that the gravitational waveforms generated through a simple application of ppBHPT to the comparable mass-ratio cases agree remarkably (and surprisingly) well with those from full numerical relativity after a rescaling of the ppBHPT’s total mass parameter. This observation and the EMRISur1dq1e4 surrogate model will enable data analysis studies in the high-mass ratio regime, including potential intermediate mass-ratio signals from LIGO/Virgo and extreme-mass ratio events of interest to the future space-based observatory LISA. Copyright © 2019, The Authors. All rights reserved.

关键词： Stars

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Removing degeneracy and multimodality in gravitational wave source parameters

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Physical Review D 2022年第12期106卷 123015-123015页

作者： Javier Roulet Seth Olsen Jonathan Mushkin Tousif Islam Tejaswi Venumadhav Barak Zackay Matias Zaldarriaga Kavli Institute for Theoretical Physics University of California at Santa Barbara Santa Barbara California 93106 USA Department of Physics Princeton University Princeton New Jersey 08540 USA Department of Particle Physics and Astrophysics Weizmann Institute of Science Rehovot 76100 Israel Department of Physics University of Massachusetts Dartmouth Massachusetts 02747 USA Department of Mathematics University of Massachusetts Dartmouth Massachusetts 02747 USA Center for Scientific Computing and Visualization Research University of Massachusetts Dartmouth Massachusetts 02747 USA Department of Physics University of California at Santa Barbara Santa Barbara California 93106 USA International Centre for Theoretical Sciences Tata Institute of Fundamental Research Bangalore 560089 India School of Natural Sciences Institute for Advanced Study 1 Einstein Drive Princeton New Jersey 08540 USA

Quasicircular binary black hole mergers are described by 15 parameters, of which gravitational wave observations can typically constrain only ∼10 independent combinations to varying degree. In this work, we devise coordinates that remove correlations, and disentangle well- and poorly-measured quantities. Additionally, we identify approximate discrete symmetries in the posterior as the primary cause of multimodality, and design a method to tackle this type of multimodality. The resulting posteriors have little structure and can be sampled efficiently and robustly. We provide a python package for parameter estimation, cogwheel, that implements these methods together with other algorithms for accelerating the inference process. One of the coordinates we introduce is a spin azimuth that is measured remarkably well in several events. We suggest this might be a sensitive indicator of orbital precession, and we anticipate that it will shed light on the occurrence of spin-orbit misalignment in nature.

关键词： Gravitational waves Astronomical black holes

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Surrogate model for gravitational wave signals from non-spinning, comparable- to large-mass-ratio black hole binaries built on black hole perturbation theory waveforms calibrated to numerical relativity

arXiv

引用

arXiv 2022年

作者： Islam, Tousif Field, Scott E. Hughes, Scott A. Khanna, Gaurav Varma, Vijay Giesler, Matthew Scheel, Mark A. Kidder, Lawrence E. Pfeiffer, Harald P. Department of Physics University of Massachusetts DartmouthMA02747 United States Department of Mathematics University of Massachusetts DartmouthMA02747 United States Center for Scientific Computing and Visualization Research University of Massachusetts DartmouthMA02747 United States Kavli Institute of Theoretical Physics University of California Santa Barbara Santa BarbaraCA93106 United States Department of Physics MIT Kavli Institute Massachusetts Institute of Technology CambridgeMA02139 United States Department of Physics University of Rhode Island KingstonRI02881 United States Am Mühlenberg 1 Potsdam14476 Germany Cornell Center for Astrophysics and Planetary Science Cornell University IthacaNY14853 United States Theoretical Astrophysics Walter Burke Institute for Theoretical Physics California Institute of Technology PasadenaCA91125 United States

We present a reduced-order surrogate model of gravitational waveforms from non-spinning binary black hole systems with comparable to large mass-ratio configurations. This surrogate model, BHPTNRSur1dq1e4, is trained on waveform data generated by point-particle black hole perturbation theory (ppBHPT) with mass ratios varying from 2.5 to 10,000. BHPTNRSur1dq1e4 extends an earlier waveform model, EMRISur1dq1e4, by using an updated transition-to-plunge model, covering longer durations up to 30,500 m1 (where m1 is the mass of the primary black hole), includes several more spherical harmonic modes up to = 10, and calibrates subdominant modes to numerical relativity (NR) data. In the comparable mass-ratio regime, including mass ratios as low as 2.5, the gravitational waveforms generated through ppBHPT agree surprisingly well with those from NR after this simple calibration step. We also compare our model to recent SXS and RIT NR simulations at mass ratios ranging from 15 to 32, and find the dominant quadrupolar modes agree to better than ≈ 10−3. We expect our model to be useful to study intermediate-mass-ratio binary systems in current and future gravitational-wave detectors. Copyright © 2022, The Authors. All rights reserved.

关键词： Waveform analysis

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