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Rapidly growing primordial black holes as seeds of the massive high-redshift JWST Galaxies

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Science China(Physics,Mechanics & Astronomy) 2024年

作者： Guan-Wen Yuan Lei Lei Yuan-Zhu Wang Bo Wang yi-ying Wang Chao Chen Zhao-Qiang Shen yi-Fu Cai yi-zhong fan Key Laboratory of Dark Matter and Space Astronomy Purple Mountain ObservatoryChinese Academy of Sciences School of Astronomy and Space Science University of Science and Technology of China Institute of High Energy Physics Chinese Academy of Sciences Deep Space Exploration Laboratory/Department of Astronomy School of Physical SciencesUniversity of Science and Technology of China Jockey Club Institute for Advanced Study The Hong Kong University of Science and Technology

A group of massive galaxies at redshifts of z 7 have been recently detected by the James Webb Space Telescope (JWST),which were unexpected to form at such an early time within the standard Big Bang *** this work,we propose that this puzzle can be explained by the presence of some primordial black holes (PBHs) with a mass of～1000M⊙.These PBHs act as seeds for early galaxy formation with masses of～108-1010M⊙at high redshift,hence accounting for the JWST *** use a hierarchical Bayesian inference framework to constrain the PBH mass distribution models,and find that the Lognormal model with the Mc～750M⊙is preferred over other *** rapidly growing BHs are expected to have strong radiation and may appear as high-redshift compact objects,similar to those recently discovered by *** we focused on PBHs in this work,the bound on the initial mass of the seed black holes remains robust even if they were formed through astrophysical channels.

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镜像量子色动力学相变解释纳赫兹随机引力波背景

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Science Bulletin 2024年第6期69卷 741-746页

作者：祖磊张弛李垚钰顾玉超蔡岳霖范一中 Key Laboratory of Dark Matter and Space Astronomy Purple Mountain ObservatoryChinese Academy of SciencesNanjing 210023China School of Astronomy and Space Science University of Science and Technology of ChinaHefei 230026China

Several Pulsar Timing Array(PTA)Collaborations have recently provided strong evidence for a n Hz Stochastic Gravitational-Wave Background(SGWB).Here we investigate the implications of a firstorder phase transition occurring within the early Universe's dark quantum chromodynamics epoch,specifically within the framework of the mirror twin Higgs dark sector *** analysis indicates a distinguishable SGWB signal originating from this phase transition,which can explain the measurements obtained by ***,a significant portion of the parameter space for the SGWB signal also effectively resolves the existing tensions in both the H_(0) and S_(8) measurements in *** intriguing correlation suggests a possible common origin of these three phenomena for 0.2<ΔN_(eff)<0.5,where the mirror dark matter component constitutes less than 30% of the total dark matter *** CMB experiments such as CMB-S4 can test this parameter region.

关键词： Mirror twin Higgs Dark matter Phase transition Gravitational wave Pulsar timing array

Is the W-boson mass enhanced by the axion-like particle,dark photon,or chameleon dark energy?

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Science China(Physics,Mechanics & Astronomy) 2022年第12期65卷 145-152页

作者： Guan-Wen Yuan Lei Zu Lei Feng yi-Fu Cai yi-zhong fan Key Laboratory of Dark Matter and Space Astronomy Purple Mountain ObservatoryChinese Academy of SciencesNanjing210023China School of Astronomy and Space Science University of Science and Technology of ChinaHefei230026China Department of Astronomy School of Physical SciencesUniversity of Science and Technology of ChinaHefei230026China CAS Key Laboratory for Researches in Galaxies and Cosmology University of Science and Technology of ChinaHefei230026China

The W-boson mass(m W=(80.4335±0.0094)Ge V)measured by the Collider Detector at Fermilab Collaboration is greater than the standard model(SM)prediction at a confidence level of 7σ,strongly suggesting the presence of new particles or *** the literature,various new particles and/or fields have been introduced to explain the astrophysical and experimental data,and their presence,in principle,may also enhance the W-boson *** this study,we investigate axion-like particle(ALP),dark photon(DP),and chameleon dark energy(DE)models for a solution to the W-boson mass *** find that the ALP and DP interpretations have been significantly narrowed down by global electroweak *** possibility of attributing the W-boson mass anomaly to the chameleon DE is ruled out by other experiments.

关键词： W-boson mass axion-like particle dark photon chameleon dark energy

The nanohertz stochastic gravitational wave background from cosmic string loops and the abundant high redshift massive galaxies

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Science China(Physics,Mechanics & Astronomy) 2023年第12期66卷 11-19页

作者： Ziwei Wang Lei Lei Hao Jiao Lei Feng yi-zhong fan Key Laboratory of Dark Matter and Space Astronomy Purple Mountain ObservatoryChinese Academy of SciencesNanjing 210023China School of Astronomy and Space Science University of Science and Technology of ChinaHefei 230026China Department of Physics McGill UniversityMontreal H3A 2T8Canada

Recently,pulsar timing array(PTA)experiments have provided compelling evidence for the existence of the nanohertz stochastic gravitational wave background(SGWB).In this work,we demonstrated that cosmic string loops generated from cosmic global strings offer a viable explanation for the observed nanohertz SGWB data,requiring a cosmic string tension parameter of log(Gμ)~-12 and a loop number density of log N~***,we revisited the impact of cosmic string loops on the abundance of massive galaxies at high ***,our analysis revealed challenges in identifying a consistent parameter space that can concurrently explain both the SGWB data and observations from the James Webb Space *** indicates the necessity for either extending the existing model employed in this research or acknowledging distinct physical origins for these two phenomena.

关键词： nanohertz stochastic gravitational-wave background cosmic string loop JamesWebb Space Telescope galaxy formation

The Synchrotron-self-Compton Radiation Accompanying Shallow Decaying X-Ray Afterglow:the Case of GRB 940217

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Chinese Journal of Astronomy and Astrophysics 2007年第4期7卷 509-515页

作者： Da-Ming Wei yi-zhong fan Purple Mountain Observatory Chinese Academy of Sciences Nanjing 210008 National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 Joint Center for Particle Nuclear Physics and Cosmology of Purple Mountain Observatory - Nanjing University Nanjing 210008 The Racah Inst. of Physics Hebrew University Jerusalem 91904 Israel Golda Meir Fellow

High energy emission （〉 tens MeV） of Gamma-Ray Bursts （GRBs） provides an important clue on the physical processes occurring in GRBs that may be correlated with the GRB early afterglow. A shallow decline phase has been well identified in about half of Swift Gamma-ray Burst x-ray afterglows. The widely considered interpretation *** a significant energy injection and possibly time-evolving shock parameter（s）. We calculate the synchrotron-self-Compton （SSC） radiation of such an external forward shock and show that it could explain the well-known long term high energy （i.e., tens MeV to GeV） afterglow of GRB 940217. We propose that cooperation of Swift and GLAST will help to reveal the nature of GRBs.

关键词： gamma-rays: bursts - ISM: jets and outflows - radiation mechanisms: non-thermal

Gyroscope Dynamic Balance Counterweight Prediction Based on Multi-Head ResGAT Networks

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Computer Modeling in Engineering & Sciences 2024年第6期139卷 2525-2555页

作者： Wuyang fan Shisheng zhong School of Mechanical Engineering Harbin Institute of TechnologyHarbin150000China

The dynamic balance assessment during the assembly of the coordinator gyroscope significantly impacts the guidance accuracy of precision-guided *** dynamic balance debugging,reliance on rudimentary counterweight empirical formulas persists,resulting in suboptimal debugging accuracy and an increased repetition *** mitigate this challenge,we present a multi-head residual graph attention network(ResGAT)model,designed to predict dynamic balance counterweights with high *** this research,we employ graph neural networks for interaction feature extraction from assembly graph *** SDAE-GPC model is designed for the assembly condition classification to derive graph data inputs for the ResGAT regression model,which is capable of predicting gyroscope counterweights under small-sample *** results of our experiments demonstrate the effectiveness of the proposed approach in predicting dynamic gyroscope counterweight in its assembly *** approach surpasses current methods in mitigating repetition rates and enhancing the assembly efficiency of gyroscopes.

关键词： Gyroscope counterweight assembly small-sample ResGAT repetition rate

Short-living Supermassive Magnetar Model for the Early X-ray Flares Following Short GRBs

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Chinese Journal of Astronomy and Astrophysics 2006年第5期6卷 513-516页

作者： Wei-Hong Gao yi-zhong fan Department of Physics and Institute of Theoretical Physics Nanjing Normal University Nanjing 210008 The Racah Inst. of Physics Hebrew University Jerusalem 91904Israel Purple Mountain Observatory Chinese Academy of Sciences Nanjing210008 Lady Davis Fellow

We suggest a short-lived supermassive magnetar model to account for the X-ray flares following short γ-ray bursts. In this model the central engine of the short γ-ray bursts is a supermassive millisecond magnetar, formed in coalescence of double neutron stars. The X-ray flares are powered by the dipole radiation of the magnetar. When the magnetar has lost a significant part of its angular momentum, it collapses to a black hole and the X-ray flares cease abruptly.

关键词： Gamma-rays bursts -- radiation mechanisms nonthermal -- magnetic fields -- stars neutron- stars rotation

Localization of q-form fields on a de Sitter brane in chameleon gravity

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Frontiers of physics 2024年第3期19卷 11-18页

作者： yi zhong Tao-Tao Sui School of Physics and Electronics Science Hunan UniversityChangsha 410082China Lanzhou Center for Theoretical Physics Key Laboratory of Theoretical Physics of Gansu Provinceand Key Laboratory of Quantum Theory and Applications of MoELanzhou UniversityLanzhou 730000China College of Physics Nanjing University of Aeronautics and AstronauticsNanjing 211106China

Recently,it was found that the vector field can be naturally localized on the thick brane in chameleon *** this work,we extend this study to encompass de Sitter brane *** focus on the localization of q-form *** scalar and vector fields can be localized on the de Sitter brane,while the KR field cannot be *** condition for localization of the scalar and vector fields is ***,we investigate the localization characteristics in two examples with given conformal factor b(ϕ).In the first case,the effective potentials and KK modes of the matter fields are obtained asymmetric even though the de Sitter brane has Z2 *** the second case,volcano-like effective potentials are generated in the de Sitter brane model.

关键词： brane q-form field chameleon gravity

Very Early Optical Afterglows for Geometric Models of X-ray Flashes and X-ray Rich GRBs

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Chinese Journal of Astronomy and Astrophysics 2007年第6期7卷 777-788页

作者： Ting Yan Da-Ming Wei yi-zhong fan Purple Mountain Observatory Chinese Academy of Sciences Nanjing 210008 National Astronomical Observatories Chinese Academy of SciencesBeijing 100012 Department of Astrophysical and Planetary Sciences University of Colorado Boulder CO 80309 USA Joint Center for Particle Nuclear Physics and Cosmology of Purple Mountain Observatory - Nanjing University Nanjing 210008 The Racah Institute of Physics Hebrew University Jerusalem 91904 Israel

If X-ray flashes （XRFs） and X-ray rich Gamma-ray Bursts （XRRGs） have the same origin as the Gamma-ray bursts （GRBs） but are viewed off-center from structured jets, their early afterglows may differ from those of GRBs, and when the ultra-relativistic outflow inter- acts with the surrounding medium, there are two shocks formed, a forward shock （FS）, and a reverse shock （RS）. We calculate numerically the early afterglow powered by uniform jets, Gaussian jets and power-law jets in the forward-reverse shock scenario. A set of differential equations govern the dynamical evolution. The synchrotron self-Compton effect has been taken into account in the calculation. In the uniform jets, the very early afterglows of XRRGs and XRFs are significantly lower than the GRBs and the observed peak times of RS emission are later in the interstellar medium environment. The RS components in XRRGs and XRFs are difficult to detect, but in the stellar wind environment, the reduction of the very early flux and the delay of the RS peak time are not so remarkable. In nonuniform jets （Gaussian and power-law jets）, where there are emission materials on the line of sight, the very early light curve resembles equivalent isotropic ejecta in general although the RS flux decay index shows notable deviations if the RS is relativistic （in stellar wind）.

关键词： X-rays general -- Gamma rays bursts -- radiation mechanisms non-thermal