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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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Possibility of measuring spin precession of the nearest supermassive black hole by using S stars

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Research in Astronomy and Astrophysics 2014年第11期14卷 1415-1422页

作者： wen-biao han Shanghai Astronomical Observatory

The supermassive black hole （SMBH） with a mass of 4 million M⊙ inside the radio source Sgr A＊ in our Galactic center is the nearest SMBH. Once S stars with a shorter period are observed, relativistic precessions especially the Lense-Thirring effect can be measured by astronomical observations at the 10 ~tas level in the future. An interesting but so far unaddressed problem is that the SMBH not only has spin but also spin precession like similar objects. We study the effect of such spin precession on the orbital precessions of orbiting stars. Our results show that the spin precession can produce a periodic oscillation in the precession of the star＇s orbital plane, but has no obvious effect on the periapse shift. For stars with an orbital period of O（0.1） yr or less, such visible oscillations occur when the SMBH＇s spin-precession period ranges from about a few tens of years to hundreds of years. The period of oscillation is the same as the one of the spin precession. In principle, the precession of this oscillating orbital plane can be observed and then the spin and spin precession of the nearest SMBH can be determined.

关键词： black hole physics -- Galaxy center -- relativity

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General formalism for dirty extreme-mass-ratio inspirals

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Science China(Physics,Mechanics & Astronomy) 2024年第7期67卷 22-29页

作者： Ye Jiang wen-biao han Shanghai Astronomical Observatory Chinese Academy of SciencesShanghai 200030China School of Astronomy and Space Science University of Chinese Academy of SciencesBeijing 100049China School of Fundamental Physics and Mathematical Sciences Hangzhou Institute for Advanced StudyUniversity of Chinese Academy of SciencesHangzhou 310024China Shanghai Frontiers Science Center for Gravitational Wave Detection Shanghai 200240China

Detecting the environment around the supermassive black holes and tests of general relativity are important applications of extreme-mass-ratio inspirals(EMRIs).There is still a challenge to efficiently describe various“dirty”impacts on the inspirals,such as dark matter,gas,dipole radiation,and electromagnetic *** this study,we find the inherent linearity of the asymptotic solution of the inhomogeneous Teukolsky *** the basis of this property,we completely decouple the factors of the perturber and the background spacetime in the energy fluxes and *** the new decoupling form,the waveforms of EMRIs with non-geodesic motion in Kerr spacetime can be conveniently *** will help to resolve the environment(including gas,field,dark matter,electromagnetic interaction)around supermassive black holes and test general relativity.

关键词： gravitational wave Teukolsky equation extreme-mass-ratio inspirals

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Exploring the nature of black hole and gravity with an imminent merging binary of supermassive black holes

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Science China(Physics,Mechanics & Astronomy) 2023年第3期66卷 76-87页

作者： Xingyu Zhong wen-biao han Ziren Luo Yueliang Wu Shanghai Astronomical Observatory Chinese Academy of SciencesShanghai 200030China Taiji Laboratory for Gravitational Wave Universe(Beijing/hangzhou) University of Chinese Academy of SciencesBeijing 100049China hangzhou Institute for Advanced Study University of Chinese Academy of SciencesHangzhou 310124China School of Astronomy and Space Science University of Chinese Academy of SciencesBeijing 100049China Institute of Mechanics Chinese Academy of SciencesBeijing 100190China Shanghai Frontiers Science Center for Gravitational Wave Detection Shanghai 200240China Institute of Theoretical Physics Chinese Academy of SciencesBeijing 100190China International Centre for Theoretical Physics Asia-Paciﬁc University of Chinese Academy of SciencesBeijing 100190China Key Laboratory of Gravitational Wave Precision Measurement of Zhejiang Province Hangzhou 310124China

A supermassive binary black-hole candidate SDSS J1430+2303 reported recently motivates us to investigate an imminent binary of supermassive black holes as potential gravitational wave source, and the radiated gravitational waves at the end of the merger are shown to be in the band of space-borne detectors. We provide a general analysis on the required detecting sensitivity needed for probing such type gravitational wave sources and make a full discussion by considering two typically designed configurations of space-borne antennas. If a source is so close, it is possible to be detected with Taiji pathfinder-plus which is proposed to be an extension for the planned Taiji pathfinder by just adding an additional satellite to the initial two satellites. The gravitational wave detection on such kind of source enables us to explore the properties of supermassive black holes and the nature of gravity.

关键词： gravitation wave SMBHBs Taiji pathfinder

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Analytical effective one-body formalism for extreme-mass-ratio inspirals with eccentric orbits

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Communications in Theoretical Physics 2021年第8期73卷 96-113页

作者： Chen Zhang wen-biao han Shu-Cheng Yang Shanghai Astronomical Observatory Chinese Academy of SciencesShanghai200030China School of Astronomy and Space Science University of Chinese Academy of Sciences Beijing100049China

Extreme-mass-ratio inspirals(EMRIs)are among the most important sources for future spaceborne gravitational wave *** this kind of system,compact objects usually orbit around central supermassive black holes on complicated ***,these trajectories are approximated as the geodesics of Kerr space-times,and orbital evolution is simulated with the help of the adiabatic ***,this approach omits the influence of the compact object on its *** this paper,using the effective one-body formalism,we analytically calculate the trajectory of a nonspinning compact object around a massive Kerr black hole in an equatorial eccentric orbit(omitting the orbital inclination)and express the fundamental orbital frequencies in explicit *** formalism includes the first-order corrections for the mass ratio in the conservative orbital ***,we insert the mass-ratio-related terms into the first post-Newtonian energy *** calculating the gravitational waves using the Teukolsky equations,we quantitatively reveal the influence of the mass of the compact object on the data *** find that the shrinking of geodesic motion by taking small objects as test particles may not be appropriate for the detection of EMRIs.

关键词： gravitational wave extreme-mass-ratio inspiral effective one-body

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Numerical simulation of the Moon's rotation in a rigorous relativistic framework

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Research in Astronomy and Astrophysics 2016年第6期16卷 59-68页

作者： Zai Wang wen-biao han Kai Tang Jin-He Tao Department of Physics Shanghai University Shanghai Astronomical Observatory Chinese Academy of Sciences

This paper describes a numerical simulation of the rigid rotation of the Moon in a relativis- tic framework. Following a resolution passed by the International Astronomical Union （IAU） in 2000, we construct a kinematieally non-rotating reference system named the Selenocentric Celestial Reference System （SCRS） and give the time transformation between the Selenocentric Coordinate Time （TCS） and Barycentric Coordinate Time （TCB）. The post-Newtonian equations of the Moon＇s rotation are written in the SCRS, and they are integrated numerically. We calculate the correction to the rotation of the Moon due to total relativistic torque which includes post-Newtonian and gravitomagnetic torques as well as geodetic precession. We find two dominant periods associated with this correction： 18.6 yr and 80.1 yr. In addition, the precession of the rotating axes caused by fourth-degree and fifth-degree harmonics of the Moon is also analyzed, and we have found that the main periods of this precession are 27.3 d, 2.9 yr, 18.6 yr and 80.1 yr.

关键词： lunar libration -- Selenocentric Celestial Reference System -- geodetic precession -- general relativity

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Estimating up-limits of eccentricities for the binary black holes in the LIGO-Virgo catalog GWTC-1

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Research in Astronomy and Astrophysics 2020年第11期20卷 283-292页

作者： Qian-Yun Yun wen-biao han Gang Wang Shu-Cheng Yang Shanghai Astronomical Observatory Chinese Academy of SciencesShanghai 200030China School of Physical Science and Technology ShanghaiTech UniversityShanghai 201210China School of Astronomy and Space Science University of Chinese Academy of SciencesBeijing 100049China

In the first Gravitational-Wave Transient Catalogue of LIGO and Virgo,all events are announced having zero *** the present paper,we investigate the performance of SEOBNRE,which is a spin-aligned eccentric waveform model in *** comparing with all the eccentric waveforms in SXS library,we find that the SEOBNRE coincides perfectly with numerical relativity *** the SEOBNRE,we re-estimate the eccentricities of all black hole merger *** find that most of these events allow a possibility for existence of initial eccentricities at 10 Hz band,but are totally circularized at the observed frequency(≥20 Hz).The upcoming update of LIGO and the next generation detector like Einstein Telescope will observe the gravitational waves starting at 10 Hz or even *** the eccentricity exists at the lower frequency,then it may significantly support the dynamical formation mechanism taking place in globular clusters.

关键词： gravitational waves stars black holes binaries general

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A long time span relativistic precession model of the Earth

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Research in Astronomy and Astrophysics 2015年第4期15卷 583-596页

作者： Kai Tang Michael H.Soffel Jin-He Tao wen-biao han Zheng-Hong Tang Shanghai Astronomical Observatory Chinese Academy of Sciences University of Chinese Academy of Sciences Lohrmann Observatory Dresden Technical University

A numerical solution to the Earth＇s precession in a relativistic framework for a long time span is presented here. We obtain the motion of the solar system in the Barycentric Celestial Reference System by numerical integration with a symplectic in- tegrator. Special Newtonian corrections accounting for tidal dissipation are included in the force model. The part representing Earth＇s rotation is calculated in the Geocentric Celestial Reference System by integrating the post-Newtonian equations of motion published by Klioner et al. All the main relativistic effects are included following Klioner et al. In particular, we consider several relativistic reference systems with cor- responding time scales, scaled constants and parameters. Approximate expressions for Earth＇s precession in the interval ~1 Myr around J2000.0 are provided. In the interval 4-2000 years around J2000.0, the difference compared to the P03 precession theory is only several arcseconds and the results are consistent with other long-term precession theories.

关键词： astrometry -- ephemeris -- post-Newtonian

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Taiji data challenge for exploring gravitational wave universe

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Frontiers of physics 2023年第6期18卷 93-106页

作者： Zhixiang Ren Tianyu Zhao Zhoujian Cao Zong-Kuan Guo wen-biao han Hong-Bo Jin Yue-Liang Wu Taiji Laboratory for Gravitational Wave Universe University of Chinese Academy of Sciences(UCAS)Beijing 100049China Peng Cheng Laboratory Shenzhen 518055China Department of Astronomy Beijing Normal UniversityBeijing 100875China School of Fundamental Physics and Mathematical Sciences Hangzhou Institute for Advanced StudyUCASHangzhou 310024China CAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Sciences UCASBeijing 100049China Shanghai Astronomical Observatory Chinese Academy of SciencesShanghai 200030China School of Astronomy and Space Science UCASBeijing 100049China International Centre for Theoretical Physics Asia-Pacific(ICTP-AP UNESCO)UCASBeijing 100190China Shanghai Frontiers Science Center for Gravitational Wave Detection Shanghai 200240China Key Laboratory of Computational Astrophysics National Astronomical ObservatoriesBeijing 100101China

The direct observation of gravitational waves(GWs)opens a new window for exploring new physics from quanta to cosmos and provides a new tool for probing the evolution of *** detection in space covers a broad spectrum ranging over more than four orders of magnitude and enables us to study rich physical and astronomical *** is a proposed space-based gravitational wave(GW)detection mission that will be launched in the *** will be exposed to numerous overlapping and persistent GW signals buried in the foreground and background,posing various data analysis *** order to empower potential scientific discoveries,the Mock Laser Interferometer Space Antenna(LISA)data challenge and the LISA data challenge(LDC)were *** LDC provides a baseline framework,the first LDC needs to be updated with more realistic simulations and adjusted detector responses for Taiji’s *** this paper,we review the scientific objectives and the roadmap for Taiji,as well as the technical difficulties in data analysis and the data generation strategy,and present the associated data *** contrast to LDC,we utilize second-order Keplerian orbit and second-generation time delay interferometry ***,we employ a new model for the extreme-mass-ratio inspiral waveform and stochastic GW background spectrum,which enables us to test general relativity and measure the non-Gaussianity of curvature ***,we present a comprehensive showcase of parameter estimation using a toy *** showcase not only demonstrates the scientific potential of the Taiji data challenge(TDC)but also serves to validate the effectiveness of the *** the first data challenge for Taiji,we aim to build an open ground for data analysis related to Taiji sources and *** details can be found on the official website(***).

关键词： gravitational wave universe evolution Taiji data challenge

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Multi boron-doping effects in hard carbon toward enhanced sodium ion storage

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Journal of Energy Chemistry 2025年第1期100卷 730-738页

作者： Peng Zheng Wang Zhou Ying Mo biao Zheng Miaomiao han Qin Zhong wenwen Yang Peng Gao Lezhi Yang Jilei Liu College of Materials Science and Engineering Hunan Joint International Laboratory of Advanced Materials and Technology for Clean Energy Hunan Province Key Laboratory for Advanced Carbon Materials and Applied Technology Hunan University Greater Bay Area Institute for Innovation Hunan University Changsha Research Institute of Mining & Metallurgy Co. LTD.

Hard carbon （HC） has been considered as promising anode material for sodium-ion batteries （SIBs）.The optimization of hard carbon’s microstructure and solid electrolyte interface （SEI） property are demonstrated effective in enhancing the Na+storage capability,however,a one-step regulation strategy to achieve simultaneous multi-scale structures optimization is highly ***,we have systematically investigated the effects of boron doping on hard carbon’s microstructure and interface chemistry.A variety of structure characterizations show that appropriate amount of boron doping can increase the size of closed pores via rearrangement of carbon layers with improved graphitization degree,which provides more Na+storage ***-situ Fourier transform infrared spectroscopy/electrochemical impedance spectroscopy （FTIR/EIS） and X-ray photoelectron spectroscopy （XPS） analysis demonstrate the presence of more BC3and less B–C–O structures that result in enhanced ion diffusion kinetics and the formation of inorganic rich and robust SEI,which leads to facilitated charge transfer and excellent rate *** a result,the hard carbon anode with optimized boron doping content exhibits enhanced rate and cycling *** general,this work unravels the critical role of boron doping in optimizing the pore structure,interface chemistry and diffusion kinetics of hard carbon,which enables rational design of sodium-ion battery anode with enhanced Na+storage performance.

关键词： X ray photoelectron spectroscopy

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