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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 noise.Addressing 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

gravitational waves and primordial black hole productions from gluodynamics by holography

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Science China(Physics,Mechanics & Astronomy) 2024年第4期67卷 31-42页

作者： Song He Li Li Zhibin Li Shao-Jiang Wang Center for Theoretical Physics and College of Physics Jilin UniversityChangchun 130012China Max Planck Institute for gravitational Physics(Albert Einstein Institute) Golm 14476Germany CAS Key laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China School of Fundamental Physics and Mathematical Sciences Hangzhou Institute for Advanced StudyUniversity of Chinese Academy of SciencesHangzhou 310024China Peng Huanwu Collaborative Center for Research and Education Beihang UniversityBeijing 100191China School of Physics and Microelectronics Zhengzhou UniversityZhengzhou 450001China

Understanding the nature of quantum chromodynamics(QCD)matter is important but challenging due to the presence of nonperturbative dynamics under extreme conditions.We construct a holographic model describing the gluon sector of QCD at finite temperatures in the non-perturbative regime.The equation of state as a function of temperature is in good accordance with the lattice QCD data.Moreover,the Polyakov loop and the gluon condensation,which are proper order parameters to capture the deconfinement phase transition,also agree quantitatively well with the lattice QCD data.We obtain a strong first-order confinement/deconfinement phase transition at Tc=276.5 Me V that is consistent with the lattice QCD prediction.Based on our model for a pure gluon hidden sector,we compute the stochastic gravitational waves and primordial black hole(PBH)productions from this confinement/deconfinement phase transition in the early universe.The resulting stochastic gravitational-wave backgrounds are found to be within detectability in the International Pulsar Timing Array and Square Kilometre Array in the near future when the associated productions of PBHs saturate the current observational bounds on the PBH abundances from the LIGO-Virgo-Collaboration O3 data.

关键词： AdS/QCD confinement/deconfinement phase transition gravitational wave primordial black hole

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

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中国科学:物理学、力学、天文学英文版 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 terms.The low-energy constants in the effective field theory are determined using the Sakai-Sugimoto model and the flat-space five-dimensional Yang-Mills action.With only two inputs,m_(ρ) and f_(π),it is possible to determine all low-energy constants without ambiguity.The 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 action.We 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 masses.Therefore,these vector mesons are crucial in the Skyrme model approach to nuclei.We 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

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

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纳米技术与精密工程(英文) 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 plasma.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 backplate.This 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 ions.In 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 grid.The 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

Design and fabrication of a compact, high-performance interference-filter-based external-cavity diode laser for use in the China Space Station

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Chinese Optics Letters 2022年第2期20卷 100-105页

作者：孟令强赵芃杨孟范超陈龙谢永王义坤边伟贾建军刘涛张首刚王建宇 School of Physics and Photoelectric Engineering Taiji Laboratory for Gravitational Wave UniverseKey Laboratory of Gravitational Wave Precision Measurement of Zhejiang ProvinceHangzhou Institute for Advanced StudyUniversity of Chinese Academy of SciencesHangzhou 310024China Key laboratory of Space Active Opto-Electronics Technology Shanghai Institute of Technical PhysicsChinese Academy of SciencesShanghai 200083China Key laboratory of Time and Frequency Primary Standards National Time Service CenterChinese Academy of SciencesXi’an 710600China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China

A hertz-linewidth ultra-stable laser(USL), which will be used to detect the clock transition line, in a strontium optical clock will be launched into the China Space Station(CSS) in late 2022. As the core of the USL, an interference-filter-based externalcavity diode laser(IF-ECDL) was developed. The IF-ECDL has a compact, stable, and environmentally insensitive design.Performances of the IF-ECDL are presented. The developed IF-ECDL can pass the aerospace environmental tests, indicating that the IF-ECDL can be suitable for space missions in the CSS.

关键词： external-cavity diode laser interference filter space application

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 roadmap.taiji-1 was launched on 31 August 2019 and its designed mission was successfully completed.The in-orbit scientific achievements of taiji-1 satellite in the first stage have been published and now it has entered the extended task phase.taiji-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

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 spacetime.The 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 geometry.The 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 spacetime.New effects of gravidynamics as extension of general relativity are particularly analyzed.All 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

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

taiji-TianQin-LISA network:Precisely measuring the Hubble constant using both bright and dark sirens

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Science China(Physics,Mechanics & Astronomy) 2024年第2期67卷 59-77页

作者： Shang-Jie Jin Ye-Zhu Zhang Ji-Yu Song Jing-Fei Zhang Xin Zhang Key laboratory of Cosmology and Astrophysics(Liaoning)&College of Sciences Northeastern UniversityShenyang 110819China Key laboratory of Data Analytics and Optimization for Smart Industry(Ministry of Education) Northeastern UniversityShenyang 110819China National Frontiers Science Center for Industrial Intelligence and Systems Optimization Northeastern UniversityShenyang 110819China

In the coming decades,the space-based gravitational-wave(GW)detectors such as taiji,TianQin,and LISA are expected to form a network capable of detecting millihertz GWs emitted by the mergers of massive black hole binaries(MBHBs).In this work,we investigate the potential of GW standard sirens from the taiji-TianQin-LISA network in constraining cosmological parameters.For the optimistic scenario in which electromagnetic(EM)counterparts can be detected,we predict the number of detectable bright sirens based on three different MBHB population models,i.e.,popⅢ,Q3d,and Q3nod.Our results show that the taijiTianQin-LISA network alone could achieve a constraint precision of 0.9%for the Hubble constant,meeting the standard of precision cosmology.Moreover,the taiji-TianQin-LISA network could effectively break the cosmological parameter degeneracies generated by the CMB data,particularly in the dynamical dark energy models.When combined with the CMB data,the joint CMB+taiji-TianQin-LISA data offerσ(w)=0.036 in the wCDM model,which is close to the latest constraint result obtained from the CMB+SN data.We also consider a conservative scenario in which EM counterparts are not available.Due to the precise sky localizations of MBHBs by the taiji-TianQin-LISA network,the constraint precision of the Hubble constant is expected to reach 1.2%.In conclusion,the GW standard sirens from the taiji-TianQin-LISA network will play a critical role in helping solve the Hubble tension and shedding light on the nature of dark energy.

关键词： space-based gravitational wave detection standard sirens the taiji-TianQin-LISA network the Hubble constant dark energy