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

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Physical Review D 2021年第8期104卷 084068-084068页

作者： Tousif Islam Scott E. Field Carl-Johan Haster Rory Smith 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 for Theoretical Physics University of California Santa Barbara California 93106 USA LIGO Laboratory Massachusetts Institute of Technology 185 Albany Street Cambridge Massachusetts 02139 USA Department of Physics and Kavli Institute for Astrophysics and Space Research Massachusetts Institute of Technology 77 Massachusetts Avenue Cambridge Massachusetts 02139 USA School of Physics and Astronomy Monash University Melbourne VIC 3800 Australia OzGrav: The ARC Centre of Excellence for Gravitational Wave Discovery Clayton VIC 3800 Australia

Intermediate mass-ratio inspiral (IMRI) binaries—containing stellar-mass black holes coalescing into intermediate-mass black holes (M>100 M⊙)—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. Because of 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 gravitational-wave 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.

关键词： Gravitation Gravitational waves

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Black hole spectroscopy for precessing binary black hole coalescences

arXiv

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arXiv 2023年

作者： Zhu, Hengrui Siegel, Harrison Mitman, Keefe Isi, Maximiliano Farr, Will M. Boyle, Michael Deppe, Nils Kidder, Lawrence E. Ma, Sizheng Moxon, Jordan Nelli, Kyle C. Pfeiffer, Harald P. Scheel, Mark A. Teukolsky, Saul A. Throwe, William Varma, Vijay Vu, Nils L. Department of Physics Princeton University Jadwin Hall Washington Road NJ08544 United States Princeton Gravity Initiative Princeton University PrincetonNJ08544 United States Department of Physics Columbia University 704 Pupin Hall 538 West 120th Street New YorkNY10027 United States Center for Computational Astrophysics Flatiron Institute New YorkNY10010 United States Walter Burke Institute for Theoretical Physics California Institute of Technology PasadenaCA91125 United States Department of Physics and Astronomy Stony Brook University Stony BrookNY11794 United States Cornell Center for Astrophysics and Planetary Science Cornell University IthacaNY14853 United States Department of Physics Cornell University IthacaNY14853 United States Perimeter Institute for Theoretical Physics 31 Caroline Streeth North WaterlooONNSL 2Y5 Canada Am Mühlenberg 1 PotsdamD-14476 Germany Department of Mathematics Center for Scientific Computing and Data Science Research University of Massachusetts DartmouthMA02747 United States

The spectroscopic study of black hole quasinormal modes in gravitational-wave ringdown observations is hindered by our ignorance of which modes should dominate astrophysical signals for different binary configurations, limiting tests of general relativity and astrophysics. In this work, we present a description of the quasinormal modes that are excited in the ringdowns of comparable mass, quasi-circular precessing binary black hole coalescences—a key region of parameter space that has yet to be fully explored within the framework of black hole spectroscopy. We suggest that the remnant perturbation for precessing and non-precessing systems is approximately the same up to a rotation, which implies that the relative amplitudes of the quasinormal modes in both systems are also related by a rotation. We present evidence for this by analyzing an extensive catalog of numerical relativity simulations. Additional structure in the amplitudes is connected to the system’s kick velocity and other asymmetries in the orbital dynamics. We find that the ringdowns of precessing systems need not be dominated by the (, m) = (2, ±2) quasinormal modes, and that instead the (2, ±1) or (2, 0) quasinormal modes can dominate. Our results are consistent with a ringdown analysis of the LIGO-Virgo gravitational wave signal GW190521, and may also help in understanding phenomenological inspiral-merger-ringdown waveform model systematics. © 2023, CC BY.

关键词： Relativity

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Fully relativistic GW/Bethe-Salpeter calculations in BerkeleyGW: implementation, symmetries, benchmarking, and performance

arXiv

引用

arXiv 2022年

作者： Barker, Bradford A. Deslippe, Jack Lischner, Johannes Jain, Manish Yazyev, Oleg V. Strubbe, David A. Louie, Steven G. Department of Physics University of California Berkeley BerkeleyCA94720 United States Materials Sciences Division Lawrence Berkeley National Laboratory BerkeleyCA94720 United States Department of Physics University of California Merced MercedCA95343 United States National Energy Research Scientific Computing Center Lawrence Berkeley National Laboratory BerkeleyCA94720 United States Department of Materials and Physics Thomas Young Centre for Theory and Simulation of Materials Imperial College London LondonSW7 2AZ United Kingdom Center for Condensed Matter Theory Department of Physics Indian Institute of Science Bangalore560012 India LausanneCH-1015 Switzerland

computing the GW quasiparticle bandstructure and Bethe-Salpeter Equation (BSE) absorption spectra for materials with spin-orbit coupling has commonly been done by treating GW corrections and spin-orbit coupling as separate perturbations to density-functional theory. However, accurate treatment of materials with strong spin-orbit coupling (such as many topological materials of recent interest, and thermoelectrics) often requires a fully relativistic approach using spinor wavefunctions in the Kohn-Sham equation and GW/BSE. Such calculations have only recently become available, in particular for the BSE. We have implemented this approach in the plane-wave pseudopotential GW/BSE code BerkeleyGW, which is highly parallelized and widely used in the electronic-structure community. We present reference results for quasiparticle bandstructures and optical absorption spectra of solids with different strengths of spin-orbit coupling, including Si, Ge, GaAs, GaSb, CdSe, Au, and Bi2Se3. The calculated quasiparticle band gaps of these systems are found to agree with experiment to within a few tens of meV. SOC splittings are found to be generally in better agreement with experiment, including quasiparticle corrections to band energies. The absorption spectrum of GaAs is not significantly impacted by the inclusion of spin-orbit coupling due to its relatively small value (0.2 eV) in the Λ direction, while the absorption spectrum of GaSb calculated with the fully-relativistic GW-BSE captures the large spin-orbit splitting of peaks in the spectrum. For the prototypical topological insulator Bi2Se3, we find a drastic change in the low-energy bandstructure compared to that of DFT, with the fully-relativistic treatment of the GW approximation correctly capturing the parabolic nature of the valence and conduction bands after including off-diagonal self-energy matrix elements. We present the detailed methodology, approach to spatial symmetries for spinors, comparison against other codes, a

关键词： Selenium compounds

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INTRODUCTION

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Bulletin of the American Meteorological Society 2024年第8期105卷 S1-S11页

作者： Boyer, T. Blunden, J. Dunn, R.J.H. NOAA/NESDIS National Centers for Environmental Information Silver Spring Maryland NOAA/NESDIS National Centers for Environmental Information Asheville North Carolina Met Office Hadley Centre Exeter United Kingdom European Centre for Medium-Range Weather Forecasts Reading United Kingdom University of Maryland College Park Maryland Scripps Institution of Oceanography University of California San Diego La Jolla California NOAA/NWS National Centers for Environmental Prediction Climate Prediction Center College Park Maryland Brandenburg University of Technology (BTU) Cottbus-Senftenberg Germany Servicio Meteorológico Nacional Buenos Aires Argentina NOAA/OAR Physical Sciences Laboratory Boulder Colorado European Centre for Medium-Range Weather Forecasts Bonn Germany Center for Geophysical Research and School of Physics University of Costa Rica San José Costa Rica Department of Meteorology and National Centre for Earth Observation University of Reading Reading United Kingdom Centro Nacional de Monitoramento e Alertas de Desastres Naturais CEMADEN São Paulo Brazil Université Grenoble Alpes Institut des Géosciences de l’Environnement IRD CNRS Grenoble INP Grenoble France Hampton University Hampton Virginia Seychelles Meteorological Authority Mahe Seychelles Section for Glaciers Ice and Snow Norwegian Water Resources and Energy Directorate Oslo Norway National Research Institute for Agriculture Food and Environment (INRAE) CARRTEL Université Savoie Mont Blanc Thonon les Bains France Graduate School of Agriculture Osaka Metropolitan University Sakai Japan Science Faculty Universidad Nacional de Colombia Bogotá Colombia University of Bremen Bremen Germany NOAA Global Monitoring Laboratory Boulder Colorado Servicio Nacional de Meteorología e Hidrología del Perú Lima Perú Centro de Investigaciones sobre Desertificación – Spanish National Research Council (CSIC-UV-GVA) Valencia Spain Hydro-Climate Extremes Lab (H-CEL) Ghent University Ghent Belgium Department o

In 2023, La Niña conditions that generally prevailed in the eastern Pacific Ocean from mid-2020 into early 2023 gave way to a strong El Niño by October. Atmospheric concentrations of Earth’s major greenhouse gases—carbon dioxide, methane, and nitrous oxide—all increased to record-high levels. The annual global average carbon dioxide concentration in the atmosphere rose to 419.3±0.1 ppm, which is 50% greater than the pre-industrial level. The growth from 2022 to 2023 was 2.8 ppm, the fourth highest in the record since the 1960s. The combined short-term effects of El Niño and the long-term effects of increasing levels of heat-trapping gases in the atmosphere contributed to new records for many essential climate variables reported here. The annual global temperature across land and oceans was the highest in records dating as far back as 1850, with the last seven months (June–December) having each been record warm. Over land, the globally averaged temperature was also record high. Dozens of countries reported record or near-record warmth for the year, including China and continental Europe as a whole (warmest on record), India and Russia (second warmest), and Canada (third warmest). Intense and widespread heatwaves were reported around the world. In Vietnam, an all-time national maximum temperature record of 44.2°C was observed at Tuong Duong on 7 May, surpassing the previous record of 43.4°C at Huong Khe on 20 April 2019. In Brazil, the air temperature reached 44.8°C in Araçuaí in Minas Gerais on 20 November, potentially a new national record and 12.8°C above normal. The effect of rising temperatures was apparent in the cryosphere, where snow cover extent by June 2023 was the smallest in the 56-year record for North America and seventh smallest for the Northern Hemisphere overall. Heatwaves contributed to the greatest average mass balance loss for Alpine glaciers around the world since the start of the record in 1970. Due to rapid volume loss beginning in 2021, St. A

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First Pulsar Polarization Array Limits on Ultralight Axion-like Dark Matter

arXiv

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arXiv 2024年

作者： Xue, Xiao Dai, Shi Luu, Hoang Nhan Liu, Tao Ren, Jing Shu, Jing Zhao, Yue Zic, Andrew Bhat, N.D. Ramesh Chen, Zu-Cheng Feng, Yi Hobbs, George Kapur, Agastya Manchester, Richard N. Mandow, Rami Mishra, Saurav Reardon, Daniel J. Russell, Christopher J. Shannon, Ryan M. Wang, Shuangqiang Zhang, Lei Zhang, Songbo Zhu, Xingjiang The Barcelona Institute of Science and Technology Campus UAB Bellaterra Barcelona08193 Spain II. Institute of Theoretical Physics Universität Hamburg Hamburg22761 Germany Deutsches Elektronen-Synchrotron DESY Notkestr. 85 Hamburg22607 Germany Australia Telescope National Facility CSIRO Space and Astronomy PO Box 76 EppingNSW1710 Australia Donostia International Physics Center Basque Country UPV/EHU San SebastianE-48080 Spain Department of Physics Jockey Club Institute for Advanced Study The Hong Kong University of Science and Technology Hong Kong Institute of High Energy Physics Chinese Academy of Sciences Beijing100049 China Center for High Energy Physics Peking University Beijing100871 China School of Physics State Key Laboratory of Nuclear Physics and Technology Peking University Beijing100871 China Beijing Laser Acceleration Innovation Center Beijing Huairou101400 China Department of Physics and Astronomy University of Utah Salt Lake CityUT84112 United States International Centre for Radio Astronomy Research Curtin University BentleyWA6102 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 Zhejiang Hangzhou311121 China Department of Physics and Astronomy MQ Research Centre in Astronomy Astrophysics and Astrophotonics Macquarie University NSW2109 Australia Centre for Astrophysics and Supercomputing Swinburne University of Technology HawthornVIC3122 Australia ARC Centre of Excellence for Gravitational Wave Astronomy CSIRO Scientific Computing Australian Technology Park Locked Bag 9013 AlexandriaNSW1435 Australia Xinjiang Astronomical Observatory Chinese Academy of Sciences Xinjiang Urumqi830011 China National Astronomical Observatories Chinese Academy of Sciences A20 Dat

We conduct the first-ever Pulsar Polarization Array (PPA) analysis to detect the ultralight Axion-Like Dark Matter (ALDM) using the polarization data of 22 millisecond pulsars from the third data release of Parkes Pulsar Timing Array. As one of the major dark matter candidates, the ultralight ALDM exhibits a pronounced wave nature on astronomical scales and offers a promising solution to small-scale structure issues within local galaxies. While the linearly polarized pulsar light travels through the ALDM galactic halo, its position angle (PA) can be subject to an oscillation induced by the ALDM Chern-Simons coupling with electromagnetic field. The PPA is thus especially suited for detecting the ultralight ALDM by correlating polarization data across the arrayed pulsars. To accomplish this task, we develop an advanced Bayesian analysis framework that allows us to construct pulsar PA residual time series, model noise contributions properly and search for pulsar cross-correlations. We find that for an ALDM density of ρ0 = 0.4 GeV/cm3, the Parkes PPA offers the best global limits on the ALDM Chern-Simons coupling, namely 10−13.5 − 10−12.2 GeV−1, for the mass range of 10−22 − 10−21 eV. The crucial role of pulsar cross-correlation in recognizing the nature of the derived limits is also highlighted. Copyright © 2024, The Authors. All rights reserved.

关键词： Dark Matter

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Reexamining Circular Dichroism in Photoemission From a Topological Insulator

arXiv

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arXiv 2025年

作者： Sidilkover, Ittai Yen, Yun D’Souza, Sunil Wilfred Schusser, Jakub Pulkkinen, Aki Rotundu, Costel R. Hashimoto, Makoto Liu, Donghui Shen, Zhi-Xun Minár, Ján Schüler, Michael Soifer, Hadas Sobota, Jonathan A. School of Physics and Astronomy Faculty of Exact Sciences Tel Aviv University Tel-Aviv6997801 Israel Center for Light-Matter Interaction Tel Aviv University Tel-Aviv6997801 Israel PSI Center for Scientific Computing Theory and Data Villigen PSI5232 Switzerland Switzerland New Technologies Research Centre University of West Bohemia Univerzitní 8 PilsenCZ-306 14 Czech Republic Stanford Institute for Materials and Energy Sciences SLAC National Accelerator Laboratory 2575 Sand Hill Road Menlo ParkCA94025 United States Geballe Laboratory for Advanced Materials Stanford University StanfordCA94305 United States Stanford Synchrotron Radiation Lightsource SLAC National Accelerator Laboratory Menlo ParkCA94025 United States Department of Physics Stanford University StanfordCA94305 United States University of Fribourg Department of Physics University of Fribourg FribourgCH-1700 Switzerland

The orbital angular momentum (OAM) of electron states is an essential ingredient for topological and quantum geometric quantities in solids. For example, Dirac surface states with helical spin- and orbital-angular momenta are a hallmark of a 3D topological insulator. Angle-resolved photoemission spectroscopy (ARPES) with variable circular light polarization, known as circular dichroism (CD), has been assumed to be a direct probe of OAM and, by proxy, of the Berry curvature of electronic bands in energy- and momentum-space. Indeed, topological surface states have been shown to exhibit angle-dependent CD (CDAD), and more broadly, CD is often interpreted as evidence of spin-orbit coupling. Meanwhile, it is well-established that CD originates from the photoemission matrix elements, which can have extrinsic contributions related to the experimental geometry and the inherently broken inversion symmetry at the sample surface. Therefore, it is important to broadly examine CD-ARPES to determine the scenarios in which it provides a robust probe of intrinsic material physics. We performed CD-ARPES on the canonical topological insulator Bi2Se3 over a wide range of incident photon energies. Not only do we observe angle-dependent CD in the surface states, as expected, but we also find CD of a similar magnitude in virtually all bulk bands. Since OAM is forbidden by inversion symmetry in the bulk, we conclude this originates from symmetry-breaking in the photoemission process. Comparison with theoretical calculations supports this view and suggests that "hidden" OAM – localized to atomic sites within each unit cell – contributes significantly. Additional effects, including inter-atomic interference and final-state resonances, are responsible for the rapid variation of the CDAD signal with photon energy. © 2025, CC BY.

关键词： Dichroism

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Divergences in gravitational-wave emission and absorption from extreme mass ratio binaries

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Physical Review D 2021年第6期104卷 064031-064031页

作者： Enrico Barausse Emanuele Berti Vitor Cardoso Scott A. Hughes Gaurav Khanna SISSA Via Bonomea 265 34136 Trieste Italy and INFN Sezione di Trieste IFPU—Institute for Fundamental Physics of the Universe Via Beirut 2 34014 Trieste Italy Department of Physics and Astronomy Johns Hopkins University 3400 North Charles Street Baltimore Maryland 21218 USA CENTRA Departamento de Física Instituto Superior Técnico—IST Universidade de Lisboa—UL Avenida Rovisco Pais 1 1049 Lisboa Portugal 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 Center for Scientific Computing and Visualization Research and Physics Department University of Massachusetts Dartmouth Massachusetts 02747 USA

A powerful technique to calculate gravitational radiation from binary systems involves a perturbative expansion: if the masses of the two bodies are very different, the “small” body is treated as a point particle of mass mp moving in the gravitational field generated by the large mass M, and one keeps only linear terms in the small mass ratio mp/M. This technique usually yields finite answers, which are often in good agreement with fully nonlinear numerical relativity results, even when extrapolated to nearly comparable mass ratios. Here we study two situations in which the point-particle approximation yields a divergent result: the instantaneous flux emitted by a small body as it orbits the light ring of a black hole, and the total energy absorbed by the horizon when a small body plunges into a black hole. By integrating the Teukolsky (or Zerilli/Regge-Wheeler) equations in the frequency and time domains we show that both of these quantities diverge. We find that these divergences are an artifact of the point-particle idealization, and are able to interpret and regularize this behavior by introducing a finite size for the point particle. These divergences do not play a role in black-hole imaging, e.g., by the Event Horizon Telescope.

关键词： Classical black holes Gravitational wave sources

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Analysis of GWTC-3 with fully precessing numerical relativity surrogate models

arXiv

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arXiv 2023年

作者： Islam, Tousif Vajpeyi, Avi Shaik, Feroz H. Haster, Carl-Johan Varma, Vijay Field, Scott E. Lange, Jacob O’Shaughnessy, Richard Smith, Rory Department of Mathematics University of Massachusetts DartmouthMA02747 United States Center for Scientific Computing and Data Science Research University of Massachusetts DartmouthMA02747 United States Department of Statistics The University of Auckland New Zealand School of Physics and Astronomy Monash University VIC3800 Australia OzGrav The ARC Centre of Excellence for Gravitational Wave Discovery ClaytonVIC3800 Australia Department of Physics and Astronomy University of Nevada Las Vegas 4505 South Maryland Parkway Las VegasNV89154 United States Nevada Center for Astrophysics University of Nevada Las VegasNV89154 United States LIGO Laboratory Massachusetts Institute of Technology CambridgeMA02139 United States Department of Physics Kavli Institute for Astrophysics and Space Research Massachusetts Institute of Technology 77 Massachusetts Ave CambridgeMA02139 United States Max Planck Institute for Gravitational Physics Albert Einstein Institute PotsdamD-14476 Germany Center for Computational Relativity and Gravitation Rochester Institute of Technology RochesterNY14623 United States University of Texas AustinTX78712 United States

The third Gravitational-Wave Transient Catalog (GWTC-3) contains 90 binary coalescence candidates detected by the LIGO-Virgo-KAGRA Collaboration (LVK). We provide a re-analysis of binary black hole (BBH) events using a recently developed numerical relativity (NR) waveform surrogate model, NRSur7dq4, that includes all ≤ 4 spin-weighted spherical harmonic modes as well as the complete physical effects of precession. Properties of the remnant black holes’ (BH’s) mass, spin vector, and kick vector are found using an associated remnant surrogate model NRSur7dq4Remnant. Both NRSur7dq4 and NRSur7dq4Remnant models have errors comparable to numerical relativity simulations and allow for high-accuracy parameter estimates. We restrict our analysis to 47 BBH events that fall within the regime of validity of NRSur7dq4 (mass ratios greater than 1/6 and total masses greater than 60M☉). While for most of these events our results match the LVK analyses that were obtained using the semi-analytical models such as IMRPhenomXPHM and SEOBNRv4PHM, we find that for more than 20% of events the NRSur7dq4 model recovers noticeably different measurements of black hole properties like the masses and spins, as well as extrinsic properties like the binary inclination and distance. For instance, GW150914_095045 exhibits noticeable differences in spin precession and spin magnitude measurements. Other notable findings include one event (GW191109_010717) that constrains the effective spin χeff to be negative at a 99.3% credible level and two events (GW191109_010717 and GW200129_065458) with well-constrained kick velocities. Furthermore, compared to the models used in the LVK analyses, NRSur7dq4 recovers a larger signal-to-noise ratio and/or Bayes factors for several events. While these findings have important astrophysical implications, some of the more interesting events are affected by transient detector noise, which can be challenging to remove from short-duration signals. Copyright © 2023, The Au

关键词： Black holes

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Saliency-Enhanced Content-Based Image Retrieval for Diagnosis Support in Dermatology Consultation: Reader Study

JMIR Dermatology

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JMIR Dermatology 2023年第1期6卷 e42129页

作者： Gassner, Mathias Garcia, Javier Barranco Tanadini-Lang, Stephanie Bertoldo, Fabio Fröhlich, Fabienne Guckenberger, Matthias Haueis, Silvia Pelzer, Christin Reyes, Mauricio Schmithausen, Patrick Simic, Dario Staeger, Ramon Verardi, Fabio Andratschke, Nicolaus Adelmann, Andreas Braun, Ralph P. Department of Radio Oncology University Hospital Zurich Zurich Switzerland Physics Department Swiss Federal Institute of Technology Zurich Zurich Switzerland Department of Radio Oncology University Hospital Zurich University of Zurich Zurich Switzerland Department of Dermatology University Hospital Zurich Zurich Switzerland ARTORG Center for Biomedical Engineering Research University of Bern Bern Switzerland Department of Radiation Oncology Inselspital Bern University Hospital Bern Switzerland Laboratory for Scientific Computing and Modelling Paul Scherrer Institut Villigen Switzerland Department of Dermatology University Hospital Zurich University of Zurich Zurich Switzerland

Background: Previous research studies have demonstrated that medical content image retrieval can play an important role by assisting dermatologists in skin lesion diagnosis. However, current state-of-the-art approaches have not been adopted in routine consultation, partly due to the lack of interpretability limiting trust by clinical users. Objective: This study developed a new image retrieval architecture for polarized or dermoscopic imaging guided by interpretable saliency maps. This approach provides better feature extraction, leading to better quantitative retrieval performance as well as providing interpretability for an eventual real-world implementation. Methods: Content-based image retrieval (CBIR) algorithms rely on the comparison of image features embedded by convolutional neural network (CNN) against a labeled data set. Saliency maps are computer vision–interpretable methods that highlight the most relevant regions for the prediction made by a neural network. By introducing a fine-tuning stage that includes saliency maps to guide feature extraction, the accuracy of image retrieval is optimized. We refer to this approach as saliency-enhanced CBIR (SE-CBIR). A reader study was designed at the University Hospital Zurich Dermatology Clinic to evaluate SE-CBIR’s retrieval accuracy as well as the impact of the participant’s confidence on the diagnosis. Results: SE-CBIR improved the retrieval accuracy by 7% (77% vs 84%) when doing single-lesion retrieval against traditional CBIR. The reader study showed an overall increase in classification accuracy of 22% (62% vs 84%) when the participant is provided with SE-CBIR retrieved images. In addition, the overall confidence in the lesion’s diagnosis increased by 24%. Finally, the use of SE-CBIR as a support tool helped the participants reduce the number of nonmelanoma lesions previously diagnosed as melanoma (overdiagnosis) by 53%. Conclusions: SE-CBIR presents better retrieval accuracy compared to traditional CBIR CNN

关键词： algorithms convolutional neural network deep learning dermatology dermoscopic images dermoscopy diagnosis image retrieval melanoma saliency maps skin cancer

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Extending black-hole remnant surrogate models to extreme mass ratios

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Physical Review D 2023年第8期108卷 084015-084015页

作者： Matteo Boschini Davide Gerosa Vijay Varma Cristóbal Armaza Michael Boyle Marceline S. Bonilla Andrea Ceja Yitian Chen Nils Deppe Matthew Giesler Lawrence E. Kidder Prayush Kumar Guillermo Lara Oliver Long Sizheng Ma Keefe Mitman Peter James Nee Harald P. Pfeiffer Antoni Ramos-Buades Mark A. Scheel Nils L. Vu Jooheon Yoo Dipartimento di Fisica “G. Occhialini ” Universitá degli Studi di Milano-Bicocca Piazza della Scienza 3 20126 Milano Italy Max Planck Institute for Gravitational Physics (Albert Einstein Institute) Am Mühlenberg 1 Potsdam 14476 Germany INFN Sezione di Milano-Bicocca Piazza della Scienza 3 20126 Milano Italy School of Physics and Astronomy & Institute for Gravitational Wave Astronomy University of Birmingham Birmingham B15 2TT United Kingdom Department of Mathematics Center for Scientific Computing and Data Science Research University of Massachusetts Dartmouth Massachusetts 02747 USA Cornell Center for Astrophysics and Planetary Science Cornell University Ithaca New York 14853 USA Nicholas and Lee Begovich Center for Gravitational-Wave Physics and Astronomy California State University Fullerton Fullerton California 92831 USA TAPIR 350-17 California Institute of Technology 1200 E California Boulevard Pasadena California 91125 USA Department of Physics Cornell University Ithaca New York 14853 USA International Centre for Theoretical Sciences Tata Institute of Fundamental Research Bangalore 560089 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 postmerger 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.

关键词： Classical black holes Gravitational wave sources Gravitational waves Astronomical black holes Numerical relativity

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