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arXiv 2024年

作者： Rogers, Axl F. van Straten, Willem Gulyaev, Sergei Parthasarathy, Aditya Hobbs, George Chen, Zu-Cheng Feng, Yi Goncharov, Boris Kapur, Agastya Liu, Xiaojin Reardon, Daniel Russell, Christopher J. Zic, Andrew Auckland University of Technology Private Bag 92006 Auckland1142 New Zealand Manly Astrophysics 15/41-42 East Esplanade ManlyNSW2095 Australia Max-Planck-Institut für Radioastronomie Auf dem Hügel 69 Bonn53121 Germany CSIRO Astronomy & Space Science Australia Telescope National Facility P.O. Box 76 EppingNSW1710 Australia Department of Physics Synergetic Innovation Center for Quantum Effects and Applications Hunan Normal University Hunan Changsha410081 China Institute of Interdisciplinary Studies Hunan Normal University Hunan Changsha410081 China Research Center for Astronomical Computing Zhejiang Laboratory Hangzhou311100 China L’AquilaI-67100 Italy INFN Laboratori Nazionali del Gran Sasso AssergiI-67100 Italy Faculty of Arts and Sciences Beijing Normal University Zhuhai519087 China Centre for Astrophysics and Supercomputing Swinburne University of Technology P.O. Box 218 HawthornVIC3122 Australia OzGrav: The Australian Research Council Centre of Excellence for Gravitational Wave Discovery HawthornVIC3122 Australia CSIRO Scientific Computing Australian Technology Park Locked Bag 9013 AlexandriaNSW1435 Australia Department of Physics and Astronomy MQ Research Centre in Astronomy Astrophysics and Astrophotonics Macquarie University NSW2109 Australia

This paper demonstrates the impact of state-of-the-art instrumental calibration techniques on the precision of arrival times obtained from 9.6 years of observations of millisecond pulsars using the Murriyang 64-m CSIRO Parkes Radio Telescope. Our study focuses on 21-cm observations of 25 high-priority pulsars that are regularly observed as part of the Parkes Pulsar Timing Array (PPTA) project, including those predicted to be the most susceptible to calibration errors. We employ Measurement Equation Template Matching (METM) for instrumental calibration and Matrix Template Matching (MTM) for arrival time estimation, resulting in significantly improved timing residuals with up to a sixfold reduction in white noise compared to arrival times estimated using Scalar Template Matching and conventional calibration based on the Ideal Feed Assumption. The median relative reduction in white noise is 33%, and the maximum absolute reduction is 4.5 µs. For PSR J0437−4715, METM and MTM reduce the best-fit power-law amplitude (2.7 σ) and spectral index (1.7 σ) of the red noise in the arrival time residuals, which can can be tentatively interpreted as mitigation of 1/f noise due to otherwise unmodeled steps in polarimetric response. These findings demonstrate the potential to directly enhance the sensitivity of pulsar timing array experiments through more accurate methods of instrumental calibration and arrival time estimation. Copyright © 2024, The Authors. All rights reserved.

关键词： Template matching

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High-precision source characterization of intermediate mass-ratio black hole coalescences with gravitational waves: The importance of higher-order multipoles

arXiv

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arXiv 2021年

作者： Islam, Tousif Field, Scott E. Haster, Carl-Johan Smith, Rory 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 for Theoretical Physics University of California Santa BarbaraCA93106 United States LIGO Laboratory Massachusetts Institute of Technology 185 Albany St CambridgeMA02139 United States Department of Physics Kavli Institute for Astrophysics and Space Research Massachusetts Institute of Technology 77 Massachusetts Ave CambridgeMA02139 United States School of Physics and Astronomy Monash University Vic3800 Australia OzGrav: The ARC Centre of Excellence for Gravitational Wave Discovery ClaytonVIC3800 Australia

Intermediate mass ratio inspiral (IMRI) binaries—containing stellar-mass black holes coalescing into intermediate-mass black holes (M > 100Mo )—are a highly anticipated source of gravitational waves (GWs) for Advanced LIGO/Virgo. Their detection and source characterization would provide a unique probe of strong-field gravity and stellar evolution. Due to the asymmetric component masses and the large primary, these systems generically excite subdominant modes while reducing the importance of the dominant quadrupole mode. Including higher order harmonics can also result in a 10% − 25% increase in signal-to-noise ratio for IMRIs, which may help to detect these systems. We show that by including subdominant GW modes into the analysis we can achieve a precise characterization of IMRI source properties. For example, we find that the source properties for IMRIs can be measured to within 2% − 15% accuracy at a fiducial signal-to-noise ratio of 25 if subdominant modes are included. When subdominant modes are neglected, the accuracy degrades to 9% − 44% and significant biases are seen in chirp mass, mass ratio, primary spin and luminosity distances. We further demonstrate that including subdominant modes in the waveform model can enable an informative measurement of both individual spin components and improve the source localization by a factor of ∼10. We discuss some important astrophysical implications of high-precision source characterization enabled by subdominant modes such as constraining the mass gap and probing formation channels. Copyright © 2021, The Authors. All rights reserved.

关键词： Signal to noise ratio

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Cost-Efficient High-Resolution Linear Absorption Spectra Through Extrapolating the Dipole Moment from Real-Time Time-Dependent Electronic-Structure Theory

arXiv

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arXiv 2023年

作者： Hauge, Eirill Kristiansen, Håkon Emil Konecny, Lukas Kadek, Marius Repisky, Michal Pedersen, Thomas Bondo Hylleraas Centre for Quantum Molecular Sciences Department of Chemistry University of Oslo P.O. Box 1033 Blindern Oslo0315 Norway Department of Numerical Analysis and Scientific Computing Simula Research Laboratory Kristian Augusts gate 23 Oslo0164 Norway Hylleraas Centre for Quantum Molecular Sciences Department of Chemistry University of Tromsø The Arctic University of Norway TromsøN-9037 Norway Max Planck Institute for the Structure and Dynamics of Matter Center for Free Electron Laser Science Luruper Chaussee 149 Hamburg22761 Germany Department of Physics Northeastern University BostonMA02115 United States Department of Physical and Theoretical Chemistry Faculty of Natural Sciences Comenius University Ilkovicova 6 BratislavaSK-84215 Slovakia

We present a novel function fitting method for approximating the propagation of the time-dependent electric dipole moment from real-time electronic structure calculations. Real-time calculations of the electronic absorption spectrum require discrete Fourier transforms of the electric dipole moment. The spectral resolution is determined by the total propagation time, i.e. the trajectory length of the dipole moment, causing a high computational cost. Our developed method uses function fitting on shorter trajectories of the dipole moment, achieving arbitrary spectral resolution through extrapolation. Numerical testing shows that the fitting method can reproduce high-resolution spectra using short dipole trajectories. The method converges with as little as 100 a.u. dipole trajectories for some systems, though the difficulty converging increases with the spectral density. We also introduce an error estimate of the fit, reliably assessing its convergence and hence the quality of the approximated spectrum. Copyright © 2023, The Authors. All rights reserved.

关键词： Electronic structure

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The NANOGrav 15 yr Data Set: Harmonic Analysis of the Pulsar Angular Correlations

arXiv

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arXiv 2024年

作者： Agazie, Gabriella Baier, Jeremy G. Baker, Paul T. Bécsy, Bence Blecha, Laura Boddy, Kimberly K. Brazier, Adam Brook, Paul R. Burke-Spolaor, Sarah Burnette, Rand Casey-Clyde, J. Andrew Charisi, Maria Chatterjee, Shami Cohen, Tyler Cordes, James M. Cornish, Neil J. Crawford, Fronefield Cromartie, H. Thankful DeCesar, Megan E. Demorest, Paul B. Deng, Heling Dey, Lankeswar Dolch, Timothy Ferrara, Elizabeth C. Fiore, William Fonseca, Emmanuel Freedman, Gabriel E. Gardiner, Emiko C. Gersbach, Kyle A. Glaser, Joseph Good, Deborah C. Gültekin, Kayhan Hazboun, Jeffrey S. Jennings, Ross J. Johnson, Aaron D. Kaplan, David L. Kelley, Luke Zoltan Key, Joey S. Laal, Nima Lam, Michael T. Lamb, William G. Larsen, Bjorn Lazio, Joseph W.T. Lewandowska, Natalia Liu, Tingting Luo, Jing Lynch, Ryan S. Ma, Chung-Pei Madison, Dustin R. McEwen, Alexander McKee, James W. McLaughlin, Maura A. Meyers, Patrick M. Mingarelli, Chiara M.F. Mitridate, Andrea Nay, Jonathan Nice, David J. Ocker, Stella Koch Olum, Ken D. Pennucci, Timothy T. Petrov, Polina Pol, Nihan S. Radovan, Henri A. Ransom, Scott M. Ray, Paul S. Runnoe, Jessie C. Saffer, Alexander Sardesai, Shashwat C. Schmitz, Kai Siemens, Xavier Simon, Joseph Siwek, Magdalena S. Smith, Tristan L. Fiscella, Sophia Sosa V. Stairs, Ingrid H. Stinebring, Daniel R. Susobhanan, Abhimanyu Swiggum, Joseph K. Taylor, Jacob Taylor, Stephen R. Turner, Jacob E. Unal, Caner Vallisneri, Michele van Haasteren, Rutger Verbiest, Joris Vigeland, Sarah J. Witt, Caitlin A. Wright, David Young, Olivia Center for Gravitation Cosmology and Astrophysics Department of Physics University of Wisconsin-Milwaukee P.O. Box 413 MilwaukeeWI53201 United States Department of Physics Oregon State University CorvallisOR97331 United States Department of Physics and Astronomy Widener University One University Place ChesterPA19013 United States Physics Department University of Florida GainesvilleFL32611 United States Department of Physics The University of Texas at Austin AustinTX78712 United States Cornell Center for Astrophysics and Planetary Science Department of Astronomy Cornell University IthacaNY14853 United States Cornell Center for Advanced Computing Cornell University IthacaNY14853 United States Institute for Gravitational Wave Astronomy School of Physics and Astronomy University of Birmingham Edgbaston BirminghamB15 2TT United Kingdom Department of Physics and Astronomy West Virginia University P.O. Box 6315 MorgantownWV26506 United States Center for Gravitational Waves and Cosmology West Virginia University Chestnut Ridge Research Building MorgantownWV26505 United States Department of Physics University of Connecticut 196 Auditorium Road U-3046 StorrsCT06269-3046 United States Department of Physics and Astronomy Vanderbilt University 2301 Vanderbilt Place NashvilleTN37235 United States Department of Physics New Mexico Institute of Mining and Technology 801 Leroy Place SocorroNM87801 United States Department of Physics Montana State University BozemanMT59717 United States Department of Physics and Astronomy Franklin & Marshall College P.O. Box 3003 LancasterPA17604 United States National Research Council Research Associate National Academy of Sciences WashingtonDC20001 United States Naval Research Laboratory WashingtonDC20375 United States George Mason University FairfaxVA22030 United States U.S. Naval Research Laboratory WashingtonDC20375 United States National Radio Astronomy Observatory 1003 Lopezville Rd. So

Pulsar timing array observations have found evidence for an isotropic gravitational wave background with the Hellings-Downs angular correlations, expected from general relativity. This interpretation hinges on the measured shape of the angular correlations, which is predominately quadrupolar under general relativity. Here we explore a more flexible parameterization: we expand the angular correlations into a sum of Legendre polynomials and use a Bayesian analysis to constrain their coefficients with the 15-year pulsar timing data set collected by the North American Nanohertz Observatory for Gravitational Waves (NANOGrav). When including Legendre polynomials with multipoles ≥ 2, we only find a significant signal in the quadrupole with an amplitude consistent with general relativity and non-zero at the ∼ 95% confidence level and a Bayes factor of 200. When we include multipoles ≤ 1, the Bayes factor evidence for quadrupole correlations decreases by more than an order of magnitude due to evidence for a monopolar signal at approximately 4 nHz which has also been noted in previous analyses of the NANOGrav 15-year data. Further work needs to be done in order to better characterize the properties of this monopolar signal and its effect on the evidence for quadrupolar angular correlations. © 2024, CC BY.

关键词： Polynomials

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Quantum computing for Climate Change Detection, Climate Modeling, and Climate Digital Twin

TechRxiv

引用

TechRxiv 2023年

作者： Otgonbaatar, Soronzonbold Nurmi, Olli Johansson, Mikael Mäkelä, Jarmo Kocman, Tadeusz Gawron, Piotr Puchala, Zbigniew Mielzcarek, Jakub Miroszewski, Artur Dumitru, Corneliu Octavian Remote Sensing Technology Institute German Aerospace Center DLR Oberpfaffenhofen Weßling82234 Germany Institut für Informatik Ludwig-Maximilians-Universität München Oettingenstr. 67 München80538 Germany VTT-Technical Research Centre of Finland Ltd Tietotie 3 Espoo02150 Finland Advanced Computing Facility CSC–IT Center for Science Ltd Keilaranta 14 Espoo02150 Finland Business Development Department AROBS Polska sp. z o.o. Trzy Lipy 3B/3.11.5 Gdansk80-172 Poland Scientific Computing and Information Technology Group AstroCeNT Nicolaus Copernicus Astronomical Center The Polish Academy of Sciences Ul. Rektorska 4 Warsaw00-614 Poland Institute of Theoretical Physics Jagiellonian University Lojasiewicza 11 Cracow30-348 Poland

This study explores the potential of quantum machine learning and quantum computing for climate change detection, climate modeling, and climate digital twin. We additionally consider the time and energy consumption of quantum machines and classical computers. Moreover, we identified several use-case instances for climate change detection, climate modeling, and climate digital twin that are challenging for conventional computers but can be tackled efficiently with quantum machines or by integrating them with classical computers. We also evaluated the efficacy of quantum annealers, quantum simulators, and universal quantum computers, each designed to solve specific types and kinds of computational problems that are otherwise difficult. © 2023, CC BY.

关键词： Remote sensing

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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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Extending black-hole remnant surrogate models to extreme mass ratios

arXiv

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arXiv 2023年

作者： Boschini, Matteo Gerosa, Davide Varma, Vijay Armaza, Cristóbal Boyle, Michael Bonilla, Marceline S. Ceja, Andrea Chen, Yitian Deppe, Nils Giesler, Matthew Kidder, Lawrence E. Kumar, Prayush Lara, Guillermo Long, Oliver Ma, Sizheng Mitman, Keefe Nee, Peter James Pfeiffer, Harald P. Ramos-Buades, Antoni Scheel, Mark A. Vu, Nils L. Yoo, Jooheon Dipartimento di Fisica "G. Occhialini" Universitá degli Studi di Milano-Bicocca Piazza della Scienza 3 Milano20126 Italy Am Mühlenberg 1 Potsdam14476 Germany INFN Sezione di Milano-Bicocca Piazza della Scienza 3 Milano20126 Italy School of Physics and Astronomy Institute for Gravitational Wave Astronomy University of Birmingham BirminghamB15 2TT United Kingdom Department of Mathematics Center for Scientific Computing and Data Science Research University of Massachusetts DartmouthMA02747 United States Cornell Center for Astrophysics and Planetary Science Cornell University IthacaNY14853 United States Nicholas and Lee Begovich Center for Gravitational-Wave Physics and Astronomy California State University FullertonCA92831 United States TAPIR 350-17 California Institute of Technology 1200 E California Boulevard PasadenaCA91125 United States Department of Physics Cornell University IthacaNY14853 United States International Centre for Theoretical Sciences Tata Institute of Fundamental Research Bangalore560089 India

Numerical-relativity surrogate models for both black-hole merger waveforms and remnants have emerged as important tools in gravitational-wave astronomy. While producing very accurate predictions, their applicability is limited to the region of the parameter space where numerical-relativity simulations are available and computationally feasible. Notably, this excludes extreme mass ratios. We present a machine-learning approach to extend the validity of existing and future numerical-relativity surrogate models toward the test-particle limit, targeting in particular the mass and spin of post-merger black-hole remnants. Our model is trained on both numerical-relativity simulations at comparable masses and analytical predictions at extreme mass ratios. We extend the gaussian-process-regression model NRSur7dq4Remnant, validate its performance via cross validation, and test its accuracy against additional numerical-relativity runs. Our fit, which we dub NRSur7dq4EmriRemnant, reaches an accuracy that is comparable to or higher than that of existing remnant models while providing robust predictions for arbitrary mass ratios. Copyright © 2023, The Authors. All rights reserved.

关键词： Black holes

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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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Accelerating quantum many-body configuration interaction with directives

arXiv

引用

arXiv 2021年

作者： Cook, Brandon Fasano, Patrick J. Maris, Pieter Yang, Chao Oryspayev, Dossay National Energy Research Scientific Computing Center Lawrence Berkeley National Laboratory BerkeleyCA United States Department of Physics University of Notre Dame Notre DameIN United States Department of Physics and Astronomy Iowa State University AmesIA United States Computational Research Division Lawrence Berkeley National Laboratory BerkeleyCA United States Computational Science Initiative Brookhaven National Laboratory UptonNY United States

Many-Fermion Dynamics—nuclear, or MFDn, is a configuration interaction (CI) code for nuclear structure calculations. It is a platform-independent Fortran 90 code using a hybrid MPI+X programming model. For CPU platforms the application has a robust and optimized OpenMP implementation for shared memory parallelism. As part of the NESAP application readiness program for NERSC’s latest Perlmutter system, MFDn has been updated to take advantage of accelerators. The current mainline GPU port is based on OpenACC. In this work we describe some of the key challenges of creating an efficient GPU implementation. Additionally, we compare the support of OpenMP and OpenACC on AMD and NVIDIA GPUs. © 2021, CC BY-NC-SA.

关键词： Quantum chemistry

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Accelerating an iterative Eigensolver for nuclear structure configuration interaction calculations on GPUs using OpenACC

arXiv

引用

arXiv 2021年

作者： Maris, Pieter Yang, Chao Oryspayev, Dossay Cook, Brandon Department Of Physics and Astronomy Iowa State University AmesIA United States Computational Research Division Lawrence Berkeley National Laboratory BerkeleyCA United States Computational Science Initiative Brookhaven National Laboratory UptonNY United States National Energy Research Scientific Computing Center Lawrence Berkeley National Laboratory BerkeleyCA United States

To accelerate the solution of large eigenvalue problems arising from many-body calculations in nuclear physics on distributed-memory parallel systems equipped with general-purpose Graphic Processing Units (GPUs), we modified a previously developed hybrid MPI/OpenMP implementation of an eigensolver written in FORTRAN 90 by using an OpenACC directives based programming model. Such an approach requires making minimal changes to the original code and enables a smooth migration of large-scale nuclear structure simulations from a distributed-memory many-core CPU system to a distributed GPU system. However, in order to make the OpenACC based eigensolver run efficiently on GPUs, we need to take into account the architectural differences between a many-core CPU and a GPU device. Consequently, the optimal way to insert OpenACC directives may be different from the original way of inserting OpenMP directives. We point out these differences in the implementation of sparse matrix-matrix multiplications (SpMM), which constitutes the main cost of the eigensolver, as well as other differences in the preconditioning step and dense linear algebra operations. We compare the performance of the OpenACC based implementation executed on multiple GPUs with the performance on distributed-memory many-core CPUs, and demonstrate significant speedup achieved on GPUs compared to the on-node performance of a many-core CPU. We also show that the overall performance improvement of the eigensolver on multiple GPUs is more modest due to the communication overhead among different MPI ranks. © 2021, CC BY-NC-ND.

关键词： Quantum chemistry

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