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The detection, extraction and parameter estimation of extreme-mass-ratio inspirals with deep learning

Science China(Physics,Mechanics & Astronomy) 2025年第1期Mechanics & Astronomy) .卷 86-96页

作者： Qianyun Yun Wen-Biao Han Yi-Yang Guo He Wang Minghui Du Hangzhou Institute for Advanced Study University of Chinese Academy of Sciences Shanghai Astronomical Observatory Chinese Academy of Sciences School of Physics and Astronomy Shanghai Jiao Tong University School of Astronomy and Space Science University of Chinese Academy of Sciences taiji laboratory for gravitational Wave universe (Beijing/Hangzhou) University of Chinese Academy of Sciences Lanzhou Center for Theoretical Physics Key Laboratory of Theoretical Physics of Gansu Province Key Laboratory of Quantum Theory and Applications of MoE Lanzhou University Institute of Theoretical Physics & Research Center of Gravitation Lanzhou University International Centre for Theoretical Physics Asia-Pacific (ICTP-AP) University of Chinese Academy of Sciences (UCAS) Center for gravitational Wave Experiment National Microgravity Laboratory Institute of Mechanics Chinese Academy of Sciences

One of the primary goals of space-borne gravitational wave detectors is to detect and analyze extreme-mass-ratio inspirals(EMRIs). This task is particularly challenging because EMRI signals are complex, lengthy, and faint. In this work, we introduce a2-layer convolutional neural network(CNN) approach to detect EMRI signals for space-borne detectors, achieving a true positive rate(TPR) of 96.9% at a 1% false positive rate(FPR) for signal-to-noise ratio(SNR) from 50 to 100. Especially, the key intrinsic parameters of EMRIs such as the mass, spin of the supermassive black hole(SMBH) and the initial eccentricity of the orbit can also be inferred directly by employing a neural network. The mass and spin of the SMBH can be determined at 99% and 92% respectively. This will greatly reduce the parameter spaces and computing cost for the following Bayesian parameter *** model also has a low dependency on the accuracy of the waveform model. This study underscores the potential of deep learning methods in EMRI data analysis, enabling the rapid detection of EMRI signals and efficient parameter estimation.

关键词： gravitational wave EMRIs deep-learing

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A study of the influence of different grid structures on plasma characteristics in the discharge chamber of an ion thruster

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Plasma Science and Technology 2023年第1期25卷 147-156页

作者：孙明明龙建飞郭伟龙刘超赵勇 Science and Technology on Vacuum Technology and Physics laboratory Lanzhou Institute of PhysicsLanzhou 730000People's Republic of China gravitational Wave universe taiji laboratory Hangzhou Institute for Advanced StudyUCASHangzhou 310024People's Republic of China Key laboratory of gravitational Wave Precision Measurement of Zhejiang Province UCASHangzhou 310024People's Republic of China

The grid structure has significant effects on the discharge characteristics of an ion *** discharge performances of a 30 cm diameter ion thruster with flat,convex and concave grids are *** analysis results show that the discharge chamber with a convex grid has a larger’magnetic-field free area’than the others,and the parallelism of the magnetic-field isopotential lines and anode is generally the same in the three *** densities of the three structures at the grid outlet are in the range of 3.1×1016-6.9×*** the thruster axis direction,the electron temperature in the chamber with the convex and concave grids is in the range of 3.3-3.5 eV,while that with a flat grid is lower,in the range of 3.1-3.5 *** addition,the convex and the concave grids have better uniform distribution of electron ***,the collision frequency ratios show that the axial degree of ionization of the three models is the highest,and the flat grid has the highest discharge efficiency,followed by the convex grid and the concave grid is the least *** test and simulation results of the 30 cm diameter ion thruster with the convex grid show that the measurement and calculation results are 3.67 A and 3.44 A,respectively,and the error above mainly comes from the ignorance of the doubly charged ions and parameter settings in the *** comparison error between the simulation and measurement of beam current density is mainly caused by the actual thermal deformation of the grids during the discharge process,which leads to the change in electric potential distribution and variation of the focusing characteristics of the *** consideration of discharge performance and the thermal grid gap variation,it can be concluded that the flat and concave grids are more suitable for small-diameter ion thrusters,while the convex grid is a more reasonable choice for the higher-power and larger-diameter thrusters.

关键词： ion thruster the grids discharge characteristics

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Vector meson effects on multi-Skyrmion states from the rational map ansatz

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Science China(Physics,Mechanics & Astronomy) 2023年第11期66卷 126-135页

作者： Jun-Shuai Wang Yong-Liang Ma College of Physics Jilin UniversityChangchun130012China School of Fundamental Physics and Mathematical Sciences Hangzhou Institute for Advanced StudyUniversity of Chinese Academy of Sciences(UCAS)Hangzhou310024China taiji laboratory for gravitational Wave universe(Beijing/Hangzhou) UCASBeijing100049China

The roles of the lightest vector mesons ρ and ω in the multi-Skyrmion states are studied using the hidden local symmetry approach up to the next-to-leading order,including the homogeneous Wess-Zumino *** low-energy constants in the effective field theory are determined using the Sakai-Sugimoto model and the flat-space five-dimensional Yang-Mills *** only two inputs,m_(ρ) and f_(π),it is possible to determine all low-energy constants without *** vector meson effects can be investigated by sequentially integrating vector mesons,and their geometry can be elucidated by comparing the results using the low-energy constants estimated from the Sakai-Sugimoto model and the flat-space five-dimensional Yang-Mills *** found that theρmeson reduces the masses of the multi-Skyrmion states and increases the overlaps of their constituents,whereas theωmeson repulses the constituents of the multi-Skyrmion states and increases their ***,these vector mesons are crucial in the Skyrme model approach to *** also found that the warping factor,an essential element in the holographic model of QCD,affects the properties of the multi-Skyrmion states and cannot be ignored.

关键词： vector meson multi-Skyrmion state rational map hidden local symmetry

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Constraints on holographic QCD phase transitions from PTA observations

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Science China(Physics,Mechanics & Astronomy) 2025年第1期Mechanics & Astronomy) .卷 71-78页

作者： Song He Li Li Sai Wang Shao-Jiang Wang Center for Theoretical Physics and College of Physics Jilin University School of Physical Science and Technology Ningbo University Max Planck Institute for gravitational Physics (Albert Einstein Institute) CAS Key laboratory of Theoretical Physics Institute of Theoretical Physics Chinese Academy of Sciences School of Fundamental Physics and Mathematical Sciences Hangzhou Institute for Advanced StudyUniversity of Chinese Academy of Sciences (UCAS) School of Physical Sciences University of Chinese Academy of Sciences (UCAS) Theoretical Physics Division Institute of High Energy Physics Chinese Academy of Sciences

The underlying physics of QCD phase transition in the early universe remains largely unknown due to its strong-coupling nature during the quark-gluon plasma/hadron gas transition, yet a holographic model has been proposed to quantitatively fit the lattice QCD data while with its duration of the first-order phase transition(FoPT) left undetermined. At specific baryon chemical potential, the first-order QCD phase transition agrees with the observational constraint of baryon asymmetry. It, therefore, provides a scenario for phase transition gravitational waves(GWs) within the standard model of particle physics. If these background GWs could contribute dominantly to the recently claimed common-spectrum red noise from pulsar timing array(PTA) observations, the duration of this FoPT can be well constrained, and the associated primordial black holes are still allowed by current observations.

关键词： pulsar timing array QCD phase transition gravitational waves primordial black holes

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taiji-1 Satellite Mission

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空间科学学报 2020年第5期40卷 691-692页

作者： LUO Ziren ZHANG Min WU Yueliang taiji laboratory for gravitational universe University of Chinese Academy of ScienceBeijing 100049 Institute of Mechanics Chinese Academy of ScienceBeijing 100190 International Centre for Theoretical Physics Asia-Pacific University of Chinese Academy of ScienceBeijing 100190

China’s first satellite to conduct experiments on key technologies related to space-based gravitational wave detection,taiji-1,has successfully completed its in-orbit tests,making a breakthrough in the country’s gravitational wave *** the success of taiji-1’s in-orbit tests,the first goal of Chinese Academy of Science’s three-step strategy to implement the taiji program has been successfully achieved.

关键词： gravitational wave taiji program Drag-free control system

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Characteristics of the pressure profile in the accelerator on the RF negative ion source at ASIPP

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Nanotechnology and Precision Engineering 2023年第3期6卷 48-54页

作者： Mingshan Wu Luxiang Xu Yanbo Zhou Lizhen Liang Yelong Zheng School of Fundamental Physics and Mathematical Sciences Key Laboratory of Gravitational Wave Precision Measurement of Zhejiang ProvinceTaiji Laboratory for Gravitational Wave UniverseHangzhou Institute for Advanced StudyUniversity of Chinese Academy of SciencesHangzhou 310024China University of Chinese Academy of Sciences Beijing 100049China Institute of Plasma Physics Chinese Academy of SciencesHefei 230031China State Key laboratory of Precision Measuring Technology and Instruments Tianjin UniversityTianjin 300072China

Neutral beam injection(NBI)systems based on negative hydrogen ion sources-rather than the positive ion sources that have typically been used to date-will be used in the future magnetically confined nuclear fusion experiments to heat the *** collisions between the fast negative ions and neutral background gas result in a significant number of high-energy positive ions being produced in the acceleration area,and for the high-power long-pulse operation of NBI systems,this acceleration of positive ions back to the ion source creates heat load and material sputtering on the source *** difficulty cannot be ignored,with the neutral gas density in the acceleration region having a significant impact on the flux density of the backstreaming positive *** the work reported here,the pressure gradient in the acceleration region was estimated using an ionization gauge and a straightforward 1D computation,and it was found that once gas traveled through the acceleration region,the pressure dropped by nearly one order of magnitude,with the largest pressure drop occurring at the plasma *** computation also revealed that the pressure drop in the grid gaps was substantially smaller than that in the grid apertures.

关键词： Pressure gradient Negative ion source Aperture conductance Neutral beam injection

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Recent Status of taiji Program in China

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空间科学学报 2022年第4期42卷 536-538页

作者： LUO Ziren ZHANG Min WU Yueliang taiji laboratory for gravitational universe University of Chinese Academy of SciencesBeijing 100049 Hangzhou Institute for Advanced Study University of Chinese Academy of SciencesHangzhou 310024 Institute of Mechanics Chinese Academy of SciencesBeijing 100190 International Center for Theoretical Physics Asia-Pacific UCASBeijing100190

The taiji-1 satellite is a pilot satellite mission of taiji program,which is used to verify taiji’s key technology and also to testify the feasibility of taiji ***-1 was launched on 31 August 2019 and its designed mission was successfully *** in-orbit scientific achievements of taiji-1 satellite in the first stage have been published and now it has entered the extended task ***-2 will prepare all the technology needed by taiji-3,and remove all the technical obstacles faced by taiji-3.

关键词： gravitational wave taiji program Global gravity field model

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A study of pulsed high voltage driven hollow-cathode electron beam sources through synchronous optical trigger

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Plasma Science and Technology 2024年第5期26卷 82-90页

作者：霍卫杰贺伟国韩罗峰朱康武王锋 Shanghai Aerospace Electronic Technology Institute Shanghai 201109People’s Republic of China School of Mechatronic Engineering and Automation Shanghai UniversityShanghai 200444People’s Republic of China School of Fundamental Physics and Mathematical Sciences Hangzhou Institute for Advanced StudyUniversity of Chinese Academy of SciencesHangzhou 310024People’s Republic of China Key laboratory of gravitational Wave Precision Measurement of Zhejiang Province Taiji Laboratory for Gravitational Wave UniverseHangzhou 310024People’s Republic of China Shanghai Aerospace Control Technology Institute Shanghai 201109People’s Republic of China

In this study,a pulsed,high voltage driven hollow-cathode electron beam sources through an optical trigger is designed with characteristics of simple structure,low cost,and easy *** validate the new design,the characteristics of hollow-cathode discharge and electron beam characterization under pulsed high voltage drive are studied experimentally and discussed by discharge characteristics and analyses of waveform details,*** validation experiments indicate that the pulsed high voltage supply significantly improves the frequency and stability of the discharge,which provides a new solution for the realization of a high-frequency,high-energy electron beam *** peak current amplitude in the high-energy electron beam increases from 6.2 A to 79.6 A,which indicates the pulsed power mode significantly improves the electron beam ***,increasing the capacitance significantly affects the highcurrent,lower-energy electron beam more than the high-energy electron beam.

关键词： hollow-cathode nanosecond pulsed electron beam sources optical trigger pulsed high voltage supply beam current distribution

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Gravidynamics,spinodynamics and electrodynamics within the framework of gravitational quantum field theory

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Science China(Physics,Mechanics & Astronomy) 2023年第6期66卷 148-190页

作者： Yue-Liang Wu International Centre for Theoretical Physics Asia-Pacific University of Chinese Academy of SciencesBeijing 100190China Institute of Theoretical Physics Chinese Academy of SciencesBeijing 100190China taiji laboratory for gravitational Wave universe(Beijing/Hangzhou) University of Chinese Academy of SciencesBejing 100049China School of Fundamental Physics and Mathematical Sciences Hangzhou Institute for Advanced StudyUniversity of Chinese Academy of SciencesHangzhou310024China

By noticing the fact that the charged leptons and quarks in the standard model are chirality-based Dirac spinors since their weak interaction violates maximally parity symmetry though they behave as Dirac fermions in electromagnetic interaction,we show that such a chirality-based Dirac spinor possesses not only electric charge gauge symmetry U(1)but also inhomogeneous spin gauge symmetry WS(1,3)=SP(1,3)?W1,3,which reveals the nature of gravity and *** gravitational force and spin gauge force are governed by the gauge symmetries W1,3and SP(1,3),respectively,and a biframe spacetime with globally fiat Minkowski spacetime as base spacetime and locally fiat gravigauge spacetime as a fiber is described by the gravigauge field through emergent non-commutative *** gauge-geometry duality and renormalizability in gravitational quantum field theory(GQFT)are carefully discussed.A detailed analysis and systematic investigation on gravidynamics and spinodynamics as well as electrodynamics are carried out within the framework of GQFT.A full discussion on the generalized Dirac equation and Maxwell equation as well as Einstein equation and spin gauge equation is made in biframe *** effects of gravidynamics as extension of general relativity are particularly *** dynamic equations of basic fields are demonstrated to preserve the spin gauge covariance and general coordinate covariance due to the spin gauge symmetry and emergent general linear group symmetry GL(1,3,R),so they hold naturally in any spinning reference frame and motional reference frame.

关键词： inhomogeneous spin gauge symmetry locally flat gravigauge spacetime gravitational relativistic quantum mechanics with generalized Dirac equation gravidynamics with generalized Einstein equation generalized Maxwell equation in any motional and spinning reference frame

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Advancing space-based gravitational wave astronomy: Rapid parameter estimation via normalizing flows

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Science China(Physics,Mechanics & Astronomy) 2024年第3期67卷 20-33页

作者： Minghui Du Bo Liang He Wang Peng Xu Ziren Luo Yueliang Wu Center for gravitational Wave Experiment National Microgravity LaboratoryInstitute of MechanicsChinese Academy of SciencesBeijing 100190China Key laboratory of gravitational Wave Precision Measurement of Zhejiang Province Hangzhou Institute for Advanced StudyUniversity of Chinese Academy of SciencesHangzhou 310024China Shanghai Institute of Optics and Fine Mechanics Chinese Academy of SciencesShanghai 201800China International Centre for Theoretical Physics Asia-Pacific University of Chinese Academy of SciencesBeijing 100049China taiji laboratory for gravitational Wave universe(Beijing/Hangzhou) University of Chinese Academy of SciencesBeijing 100049China Lanzhou Center of Theoretical Physics Lanzhou UniversityLanzhou 730000China Hangzhou Institute for Advanced Study University of Chinese Academy of SciencesHangzhou 310024China Institute of Theoretical Physics Chinese Academy of SciencesBeijing 100190China

gravitational wave(GW) astronomy is witnessing a transformative shift from terrestrial to space-based detection, with missions like taiji at the forefront. While the transition brings unprecedented opportunities for exploring massive black hole binaries(MBHBs), it also imposes complex challenges in data analysis, particularly in parameter estimation amidst confusion *** this gap, we utilize scalable normalizing flow models to achieve rapid and accurate inference within the taiji environment. Innovatively, our approach simplifies the data's complexity, employs a transformation mapping to overcome the year-period time-dependent response function, and unveils additional multimodality in the arrival time parameter. Our method estimates MBHBs several orders of magnitude faster than conventional techniques, maintaining high accuracy even in complex backgrounds. These findings significantly enhance the efficiency of GW data analysis, paving the way for rapid detection and alerting systems and enriching our ability to explore the universe through space-based GW observation.

关键词： taiji program gravitational wave detection parameter estimation machine learning

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