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Meeting the Challenges of Modeling Astrophysical Thermonuclear Explosions: Castro, Maestro, and the AMReX Astrophysics Suite

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Journal of physics: Conference Series 2018年第1期1031卷

作者： M. Zingale A. S. Almgren M. G. Barrios Sazo V. E. Beckner J. B. Bell B. Friesen A. M. Jacobs M. P. Katz C. M. Malone A. J. Nonaka D. E. Willcox W. Zhang Department of Physics and Astronomy Stony Brook University Stony Brook NY 11794-3800 USA Center for Computational Sciences and Engineering Lawrence Berkeley National Lab Berkeley CA 94720 USA National Energy Research Scientific Computing Center Lawrence Berkeley National Lab Berkeley CA 94720 USA Department of Physics and Astronomy Michigan State University East Lansing Michigan 48824 USA NVIDIA Corporation 2788 San Tomas Expressway Santa Clara CA 95050 USA Los Alamos National Laboratory Los Alamos NM 87545 USA

We describe the AMReX suite of astrophysics codes and their application to modeling problems in stellar astrophysics. Maestro is tuned to efficiently model subsonic convective flows while Castro models the highly compressible flows associated with stellar explosions. Both are built on the block-structured adaptive mesh refinement library AMReX. Together, these codes enable a thorough investigation of stellar phenomena, including Type Ia supernovae and X-ray bursts. We describe these science applications and the approach we are taking to make these codes performant on current and future many-core and GPU-based architectures.

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Calm multi-baryon operators

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arXiv 2017年

作者： Berkowitz, Evan Nicholson, Amy Chang, Chia Cheng Rinaldi, Enrico Clark, M.A. Joó, Bálint Kurth, Thorsten Vranas, Pavlos Walker-Loud, André Institut für Kernphysik Institute for Advanced Simulation Forschungszentrum Jülich Department of Physics University of California Berkeley United States Nuclear Science Division Lawrence Berkeley National Laboratory Department of Physics and Astronomy University of North Carolina Chapel Hill United States RIKEN-BNL Research Center Brookhaven National Laboratory NVIDIA Corporation Scientific Computing Group Thomas Jefferson National Accelerator Facility NERSC Lawrence Berkeley National Laboratory Nuclear and Chemical Sciences Division Lawrence Livermore National Laboratory

There are many outstanding problems in nuclear physics which require input and guidance from lattice QCD calculations of few baryons systems. However, these calculations suffer from an exponentially bad signal-to-noise problem which has prevented a controlled extrapolation to the physical point. The variational method has been applied very successfully to two-meson systems, allowing for the extraction of the two-meson states very early in Euclidean time through the use of improved single hadron operators. The sheer numerical cost of using the same techniques in two-baryon systems has so far been prohibitive. We present an alternate strategy which offers some of the same advantages as the variational method while being significantly less numerically expensive. We first use the Matrix Prony method to form an optimal linear combination of single baryon interpolating fields generated from the same source and different sink interpolating fields. Very early in Euclidean time this optimal linear combination is numerically free of excited state contamination, so we coin it a calm baryon. This calm baryon operator is then used in the construction of the two-baryon correlation functions. To test this method, we perform calculations on theWM/JLab iso-clover gauge configurations at the SU(3) flavor symmetric point with mπ ∼800 MeV -the same configurations we have previously used for the calculation of two-nucleon correlation functions. We observe the calm baryon significantly removes the excited state contamination from the two-nucleon correlation function to as early a time as the single-nucleon is improved, provided non-local (displaced nucleon) sources are used. For the local two-nucleon correlation function (where both nucleons are created from the same space-time location) there is still improvement, but there is significant excited state contamination in the region the single calm baryon displays no excited state contamination. Copyright © 2017, The Authors. All rights re

关键词： Hadrons

Meeting the Challenges of Modeling Astrophysical Thermonuclear Explosions: Castro, Maestro, and the AMReX Astrophysics Suite

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arXiv 2017年

作者： Zingale, M. Almgren, A.S. Sazo, M.G. Barrios Beckner, V.E. Bell, J.B. Friesen, B. Jacobs, A.M. Katz, M.P. Malone, C.M. Nonaka, A.J. Willcox, D.E. Zhang, W. Department of Physics and Astronomy Stony Brook University Stony BrookNY11794-3800 United States Center for Computational Sciences and Engineering Lawrence Berkeley National Lab BerkeleyCA94720 United States National Energy Research Scientific Computing Center Lawrence Berkeley National Lab BerkeleyCA94720 United States Department of Physics and Astronomy Michigan State University East LansingMI48824 United States NVIDIA Corporation 2788 San Tomas Expressway Santa ClaraCA95050 United States Los Alamos National Laboratory Los AlamosNM87545 United States

关键词： Astrophysics

Parkes Pulsar Timing Array constraints on ultralight scalar-field dark matter

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arXiv 2018年

作者： Porayko, Nataliya K. Zhu, Xingjiang Levin, Yuri Hui, Lam Hobbs, George Grudskaya, Aleksandra Postnov, Konstantin Bailes, Matthew Bhat, N.D. Ramesh Coles, William Dai, Shi Dempsey, James Keith, Michael J. Kerr, Matthew Kramer, Michael Lasky, Paul D. Manchester, Richard N. Oslowski, Stefan Parthasarathy, Aditya Ravi, Vikram Reardon, Daniel J. Rosado, Pablo A. Russell, Christopher J. Shannon, Ryan M. Spiewak, Renée van Straten, Willem Toomey, Lawrence Wang, Jingbo Wen, Linqing You, Xiaopeng Max-Planck-Institut für Radioastronomie Auf dem Hügel 69 BonnD-53121 Germany School of Physics and Astronomy Monash University ClaytonVIC3800 Australia School of Physics University of Western Australia CrawleyWA6009 Australia Australian Research Council Centre of Excellence for Gravitational Wave Discovery Center for Theoretical Physics Department of Physics Columbia University New YorkNY10027 United States Center for Computational Astrophysics Flatiron Institute New YorkNY10010 United States CSIRO Astronomy and Space Science P.O. Box 76 EppingNSW1710 Australia Sternberg Astronomical Institute Lomonosov Moscow State University Universitetskii pr. 13 Moscow119234 Russia Kazan Federal University Kremlevskaya 18 Kazan420008 Russia Centre for Astrophysics and Supercomputing Swinburne University of Technology P.O. Box 218 HawthornVIC3122 Australia International Centre for Radio Astronomy Research Curtin University BentleyWA6102 Australia Department of Electrical and Computer Engineering University of California at San Diego La JollaCA92093 United States CSIRO Information Management and Technology PO Box 225 DicksonACT2602 Australia Jodrell Bank Centre for Astrophysics University of Manchester ManchesterM13 9PL United Kingdom Space Science Division Naval Research Laboratory WashingtonDC20375 United States Cahill Center for Astronomy and Astrophysics California Institute of Technology MC 249-17 PasadenaCA91125 United States CSIRO Scientific Computing Australian Technology Park Locked Bag 9013 AlexandriaNSW1435 Australia Institute for Radio Astronomy & Space Research Auckland University of Technology Private Bag 92006 Auckland1142 New Zealand Xinjiang Astronomical Observatory Chinese Academy of Sciences 150 Science 1-Street Urumqi Xinjiang830011 China School of Physical Science and Technology Southwest University Chongqing400715 China

It is widely accepted that dark matter contributes about a quarter of the critical mass-energy density in our Universe. The nature of dark matter is currently unknown, with the mass of possible constituents spanning nearly one hundred orders of magnitude. The ultralight scalar field dark matter, consisting of extremely light bosons with m ∼ 10−22 eV and often called "fuzzy" dark matter, provides intriguing solutions to some challenges at sub-Galactic scales for the standard cold dark matter model. As shown by Khmelnitsky and Rubakov, such a scalar field in the Galaxy would produce an oscillating gravitational potential with nanohertz frequencies, resulting in periodic variations in the times of arrival of radio pulses from pulsars. The Parkes Pulsar Timing Array (PPTA) has been monitoring 20 millisecond pulsars at two to three weeks intervals for more than a decade. In addition to the detection of nanohertz gravitational waves, PPTA offers the opportunity for direct searches for fuzzy dark matter in an astrophysically feasible range of masses. We analyze the latest PPTA data set which includes timing observations for 26 pulsars made between 2004 and 2016. We perform a search in this data set for evidence of ultralight dark matter in the Galaxy using Bayesian and Frequentist methods. No statistically significant detection has been made. We, therefore, place upper limits on the local dark matter density. Our limits, improving on previous searches by a factor of 2 to 5, constrain the dark matter density of ultralight bosons with m ≤ 10−23 eV to be below 6 GeV cm−3 with 95% confidence in the Earth neighborhood. Finally, we discuss the prospect of probing the astrophysically favored mass range m & 10−22 eV with next-generation pulsar timing facilities. Copyright © 2018, The Authors. All rights reserved.

关键词： Timing circuits

A language and hardware independent approach to quantum-classical computing

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arXiv 2017年

作者： McCaskey, A.J. Dumitrescu, E.F. Liakh, D. Chen, M. Feng, W. Humble, T.S. Quantum Computing Institute Oak Ridge National Laboratory Oak RidgeTN United States Computer Science and Mathematics Division Oak Ridge National Laboratory Oak RidgeTN37831 United States Computational Sciences and Engineering Division Oak Ridge National Laboratory Oak RidgeTN37831 United States Oak Ridge Leadership Computing Facility Scientific Computing Oak Ridge National Laboratory Oak RidgeTN United States Department of Physics Virginia Tech BlacksburgVA United States Department of Computer Science Virginia Tech BlacksburgVA United States Bredesen Center for Interdisciplinary Research University of Tennessee KnoxvilleTN United States

Heterogeneous high-performance computing (HPC) systems offer novel architectures which accelerate specific workloads through judicious use of specialized coprocessors. A promising architectural approach for future scientific computations is provided by heterogeneous HPC systems integrating quantum processing units (QPUs). To this end, we present XACC (eXtreme-scale ACCelerator) - a programming model and software framework that enables quantum acceleration within standard or HPC software workflows. XACC follows a coprocessor machine model that is independent of the underlying quantum computing hardware, thereby enabling quantum programs to be defined and executed on a variety of QPUs types through a unified application programming interface. Moreover, XACC defines a polymorphic low-level intermediate representation, and an extensible compiler frontend that enables language independent quantum programming, thus promoting integration and interoperability across the quantum programming landscape. In this work we define the software architecture enabling our hardware and language independent approach, and demonstrate its usefulness across a range of quantum computing models through illustrative examples involving the compilation and execution of gate and annealing-based quantum programs. Copyright © 2017, The Authors. All rights reserved.

关键词： Quantum computers

Control of the dipole layer of polar organic molecules adsorbed on metal surfaces via different charge-transfer channels

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Physical Review B 2017年第8期95卷 085425-085425页

作者： Meng-Kai Lin Yasuo Nakayama Ying-Jie Zhuang Kai-Jun Su Chin-Yung Wang Tun-Wen Pi Sebastian Metz Theodoros A. Papadopoulos T.-C. Chiang Hisao Ishii S.-J. Tang Department of Physics and Astronomy National Tsing Hua University Hsinchu Taiwan 30013 Republic of China Department of Pure and Applied Chemistry Tokyo University of Science 2641 Yamazaki Noda Chiba 278-8510 Japan National Synchrotron Radiation Research Center (NSRRC) Hsinchu Taiwan 30076 Republic of China Scientific Computing Department STFC Daresbury Laboratory Daresbury Warrington WA4 4AD United Kingdom Department of Natural Sciences University of Chester Thornton Science Park Chester CH2 4NU United Kingdom Department of Physics University of Illinois at Urbana-Champaign 1110 West Green Street Urbana Illinois 61801-3080 USA Graduate School of Advanced Integration Science Chiba University 1-33 Yayoi-cho Inage-ku Chiba 263-8522 Japan Center for Frontier Science Chiba University 1-33 Yayoi-cho Inage-ku 263-8522 Japan

Organic molecules with a permanent electric dipole moment have been widely used as a template for further growth of molecular layers in device structures. Key properties of the resulting organic films such as energy level alignment (ELA), work function, and injection/collection barrier are linked to the magnitude and direction of the dipole moment at the interface. Using angle-resolved photoemission spectroscopy (ARPES), we have systematically investigated the coverage-dependent work function and spectral line shapes of occupied molecular energy states (MESs) of chloroaluminium-phthalocyanine (ClAlPc) grown on Ag(111). We demonstrate that the dipole orientation of the first ClAlPc layer can be controlled by adjusting the deposition rate and postannealing conditions, and we find that the ELA at the interface differs by ∼0.4eV between the Cl up and down configurations of the adsorbed ClAlPc molecules. These observations are rationalized by density functional theory (DFT) calculations based on a realistic model of the ClAlPc/Ag(111) interface, which reveal that the different orientations of the ClAlPc dipole layer lead to different charge-transfer channels between the adsorbed ClAlPc and Ag(111) substrate. Our findings provide a useful framework toward method development for ELA tuning.

关键词： Adsorption Electronic structure Electronic structure of atoms & molecules Angle-resolved photoemission spectroscopy Density functional theory

Electron contribution to (g-2)μ at four loops

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Electron contribution to (g-2)μ at four loops

2016 Workshop on Loops and Legs in Quantum Field Theory, LL 2016

作者： Kurz, Alexander Liu, Tao Marquard, Peter Smirnov, Alexander V. Smirnov, Vladimir A. Steinhauser, Matthias Karlsruhe76128 Germany Department of Physics University of Alberta EdmontonABT6G 2J1 Canada Deutsches Elektronen Synchrotron DESY Platanenallee 6 Zeuthen15738 Germany Scientific Research Computing Center Moscow State University Moscow119991 Russia Skobeltsyn Institute of Nuclear Physics Moscow State University Moscow119991 Russia

In this contribution we summarize the recent calculation of the complete electron contribution to the anomalous magnetic moment of the muon at four-loop order. © Copyright owned by the author(s) under the terms o...

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Hubble Tarantula treasury project-VI. Identification of pre-main-sequence stars using machine learning techniques

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arXiv 2018年

作者： Ksoll, Victor F. Gouliermis, Dimitrios A. Klessen, Ralf S. Grebel, Eva K. Sabbi, Elena Anderson, Jay Lennon, Daniel J. Cignoni, Michele de Marchi, Guido Smith, Linda J. Tosi, Monica van der Marel, Roeland P. Institut fur Theoretische Astrophysik Zentrum fur Astronomie der Universität Heidelberg Albert-Ueberle-Str. 2 Heidelberg69120 Germany Interdisciplinary Center for Scientific Computing University of Heidelberg Mathematikon Im Neuenheimer Feld 205 Heidelberg69120 Germany Max Planck Institute for Astronomy Konigstuhl 17 Heidelberg69117 Germany Astronomisches Rechen-Institut Zentrum für Astronomie der Universität Heidelberg Monchhofstr. 12-14 Heidelberg69120 Germany Space Telescope Science Institute 3700 San Martin Drive BaltimoreMD21218 United States ESA-European Space Astronomy Center Apdo. de Correo 78 Associate Villanueva de la Canada MadridE-28691 Spain Department of Physics University of Pisa Largo Pontecorvo 3 PisaI-56127 Italy European Space Research and Technology Centre Keplerlaan 1 Noordwijk2200 AG Netherlands European Space Agency Space Telescope Science Institute 3700 San Martin Drive BaltimoreMD21218 United States INAF-Osservatorio Astronomico di Bologna Via Ranzani 1 BolognaI-40127 Italy

The Hubble Tarantula Treasury Project (HTTP) has provided an unprecedented photometric coverage of the entire star-burst region of 30 Doradus down to the half Solar mass limit. We use the deep stellar catalogue of HTTP to identify all the pre-main-sequence (PMS) stars of the region, i.e., stars that have not started their lives on the main-sequence yet. The photometric distinction of these stars from the more evolved populations is not a trivial task due to several factors that alter their colour-magnitude diagram positions. The identification of PMS stars requires, thus, sophisticated statistical methods. We employ Machine Learning Classification techniques on the HTTP survey of more than 800,000 sources to identify the PMS stellar content of the observed field. Our methodology consists of 1) carefully selecting the most probable low-mass PMS stellar population of the star-forming cluster NGC2070, 2) using this sample to train classification algorithms to build a predictive model for PMS stars, and 3) applying this model in order to identify the most probable PMS content across the entire Tarantula Nebula. We employ Decision Tree, Random Forest and Support Vector Machine classifiers to categorise the stars as PMS and Non-PMS. The Random Forest and Support Vector Machine provided the most accurate models, predicting about 20,000 sources with a candidateship probability higher than 50 percent, and almost 10,000 PMS candidates with a probability higher than 95 percent. This is the richest and most accurate photometric catalogue of extragalactic PMS candidates across the extent of a whole star-forming complex. Copyright © 2018, The Authors. All rights reserved.

关键词： Photometry

Phase transitions of the coherently coupled two-component Bose gas in a square optical lattice

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arXiv 2017年

作者： Bornheimer, Ulrike Vasić, Ivana Hofstetter, Walter Centre for Quantum Technologies National University of Singapore 3 Science Drive 2 117543 Singapore MajuLab CNRS-UNS-NUS-NTU International Joint Research Unit Umi 3654 Physics Department Faculty of Science National University of Singapore 2 Science Drive 3 117551 Singapore Institut für Theoretische Physik Goethe-Universität Frankfurt Am Main Max-von-Laue-Straße 1 Frankfurt am Main60438 Germany Scientific Computing Laboratory Center for the Study of Complex Systems Institute of Physics Belgrade University of Belgrade Pregrevica 118 Belgrade11080 Serbia

We investigate properties of an ultracold, two-component bosonic gas in a square optical lattice at unit filling. In addition to density-density interactions, the atoms are subject to coherent lightmatter interactions that couple different internal states. We examine the influence of this coherent coupling on the system and its quantum phases by using Gutzwiller mean field theory as well as bosonic dynamical mean field theory. We find that the interplay of strong inter-species repulsion and coherent coupling affects the Mott insulator to superfluid transition and shifts the tip of the Mott lobe toward higher values of the tunneling amplitude. In the strongly interacting Mott regime, the resulting Bose-Hubbard model can be mapped onto an effective spin Hamiltonian that offers additional insights into the observed phenomena. Copyright © 2017, The Authors. All rights reserved.

关键词： Bosons