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Characteristics of Double Gamma-Ray Bursts

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Chinese physics Letters 2014年第11期31卷 163-165页

作者：刘彤孙谋远侯书进李昂张富文顾为民卢炬甫 department of astronomy and institute of theoretical physics and Astrophysics Xiamen University Xiamen 361005 Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming 650011 State Key Laboratory of theoretical physics Institute of Theoretical Physics Chinese Academy of Sciences Beijing 100190 department of astronomy and Astrophysics and institute for Gravitation and the Cosmos Pennsylvania State University University Park PA 16802 USA College of physics and Electronic Engineering Nanyang Normal University Nanyang 473061 College of Science Guilin University of Technology Guilin 541004

Double gamma-ray bursts （DGRBs） have two well-separated sub-bursts in the main prompt emission and the typical time interval between them is in the hundreds of seconds. Among DGRBs, gamma-ray bursts （DGRBs） 110801A and 120716A are the ones with known redshifts. However, unlike GRB 110801A, we show that the two sub-bursts of GRB 120716A is severally similar to the short- and long-duration GRBs, thus it is difficult to explain the origin of GRB 120716A by the popular models on the central engine of GRBs. We suggest that some mechanisms of x-ray flares in GRBs, i.e., a post-merger millisecond pulsars or the jet precession in a black hole hyperaccretion system may produce the DGRB.

关键词： Gamma rays

Maximal possible accretion rates for slim disks

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Science China(physics,Mechanics & astronomy) 2009年第12期52卷 2054-2058页

作者： LIN YiQing1 & JIAO ChengLiang2 1 department of Mathematics and physics,Xiamen University of Technology,Xiamen 361024,China 2 department of physics and institute of theoretical physics and Astrophysics,Xiamen University,Xiamen 361005,China department of Mathematics and physics Xiamen University of Technology Xiamen China department of physics and institute of theoretical physics and Astrophysics Xiamen University Xiamen China

It was proved in the previous work that there must be a maximal possible accretion rate $ \dot M_{max} $ for a slim disk. Here we discuss how the value of $ \dot M_{max} $ depends on the two fundamental parameters of the disk, namely the mass of the central black hole M and the viscosity parameter α. It is shown that $ \dot M_{max} $ increases with decreasing α, but is almost independent of M if $ \dot M_{max} $ is measured by the Eddington accretion rate $ \dot M_{Edd} $ , which is in turn proportional to M.

关键词： accretion disks black hole physics hydrodynamics

Diquark mass differences from unquenched lattice QCD

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Chinese physics C 2016年第7期40卷 43-54页

作者：毕玉江蔡浩陈莹宫明刘朝峰乔豪学杨一玻 School of physics and Technology Wuhan Universitv Wuhan 430072 China institute of High Energy physics and theoretical physics Center for Science Facilities Chinese Academy of Sciences Beijing 100049 China department of physics and astronomy University of Kentucky Lexington KY 40506 USA

We calculate diquark correlation functions in the Landau gauge on the lattice using overlap valence quarks and 2＋1flavor domain wall fermion configurations. Quark masses are extracted from the scalar part of quark propagators in the Landau gauge. The scalar diquark quark mass difference and axial vector scalar diquark mass difference are obtained for diquarks composed of two light quarks and of a strange and a light quark. The light sea quark mass dependence of the results is examined. Two lattice spacings are used to check the discretization effects. The coarse and fine lattices are of sizes 24^3 ×64 and 32^3 ×64 with inverse spacings 1/a= 1.75（4） GeV and 2.33（5） GeV, respectively.

关键词： lattice QCD diquarks overlap fermions Landau gauge

Energy budget of cosmological first-order phase transition in FLRW background

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Science China(physics,Mechanics & astronomy) 2018年第8期61卷 33-53页

作者： Rong-Gen Cai Shao-Jiang Wang Key Laboratory of theoretical physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China department of physics Helsinki Institute of PhysicsUniversity of HelsinkiHelsinki F1-00014Finland School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China

We study the hydrodynamics of bubble expansion in cosmological first-order phase transition in the Fdedmann-LemMtre- Robertson-Walker （FLRW） background with probe limit. Different from previous studies for fast first-order phase transition in flat background, we find that, for slow first-order phase transition in FLRW background with a given peculiar velocity of the bubble wall, the efficiency factor of energy transfer into bulk motion of thermal fluid is significantly reduced, thus decreasing the previously-thought dominated contribution from sound wave to the stochastic gravitational-wave background.

关键词： cosmological first-order phase transition bubble expansion hydrodynamics

Relativistic theoretical Calculation of O III:Radiative Transition Rates and the Bowen Mechanism in Planetary Nebulae

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Chinese physics Letters 1994年第2期11卷 69-72页

作者： TONG Xiaomin ZOU Yu LI Jiaming LIU Xiaowei institute of physics Academia SinicaBeijing 100080 department of physics and astronomy University College LondonUK

A full relativistic configuration interaction(RCI)calculation of transition energies and radiative transition rates involved in O III Bowen fluorescence mechanism is *** calculated ratios of transition line intensities are in good agreement with the observed *** discrepancies between the RCI calculation and prediction based on LS coupling scheme show that a delicate balance between the electron correlations and the spin-orbital interactions should be important even for the low-Z O Ⅲ ion.

关键词： Transition transition orbital

Propulsive matrix of a helical flagellum

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Chinese physics B 2014年第11期23卷 51-56页

作者：张何朋刘斌 Bruce Rodenborn Harry L.Swinney department of physics and astronomy and institute of Natural Sciences School of Natural Sciences University of California department of physics and Center for Nonlinear Dynamics University of Texas at Austin

We study the propulsion matrix of bacterial flagella numerically using slender body theory and the regularized Stokeslet method in a biologically relevant parameter regime. All three independent elements of the matrix are measured by computing propulsive force and torque generated by a rotating flagellum, and the drag force on a translating flagellum. Nu- merical results are compared with the predictions of resistive force theory, which is often used to interpret micro-organism propulsion. Neglecting hydrodynamic interactions between different parts of a flagellum in resistive force theory leads to both qualitative and quantitative discrepancies between the theoretical prediction of resistive force theory and the numerical results. We improve the original theory by empirically incorporating the effects of hydrodynamic interactions and propose new expressions for propulsive matrix elements that are accurate over the parameter regime explored.

关键词： low-Reynolds-number flows micro-organism dynamics bacterial swimming

Measurements of the equivalent thicknesses of three-dimensional spiral galactic disks

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Research in astronomy and Astrophysics 2009年第8期9卷 883-887页

作者： Gang Li Zhi-Quan Luo Qiu-He Peng institute of theoretical physics China West Normal University Nanchong 637002 China department of astronomy Nanjing University Nanjing 210093 China

Spiral arms are fitted after the data from the latest spiral galactic images released by the Sloan Digital Sky Survey are processed. Equivalent thicknesses of 42 spiral galactic disks are derived, which increase the f... 详细信息

关键词： galaxies spiral -- Galaxy disk

Collapse Velocity and Prompt Explosion for the Presupernova Model Ws15M_⊙

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Chinese Journal of astronomy and Astrophysics 2006年第4期6卷 455-460页

作者： Zhi-Quan Luo Men-Quan Liu Qiu-He Peng Zuo-Heng Xie institute of theoretical physics China West Normal University Nanchong 637002 department of physics Sichuan University Chengdu 610065 department of astronomy Nanjing University Nanjing 210093 institute of Applied Mathematics Chinese Academy of Sciences Beijing 100080

For the presupernova modelWs15M⊙, we re-calculate the electron capture （EC） timescale and hydrodynamical （HD） timescale. We found that the EC timescale can be smaller than the HD timescale in the inner region of the collapse iron core at the moment immediately before the shock wave bounce. The change in these two timescales at the late stage of core collapse is expected to affect the collapse velocity. If the late-time collapse velocity is artificially increased by a small quantity, then prompt explosion of the supernova may happen. Further calculations are still needed to check the plausibility of the acceleration mechanism caused by the faster EC process.

关键词： star: supernova-- nuclear reaction -- nucleosynthesis

Comparison of dark energy models:A perspective from the latest observational data

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Science China(physics,Mechanics & astronomy) 2010年第9期53卷 1631-1645页

作者： LI Miao1,2,LI XiaoDong2,3 & ZHANG Xin1,4 1Kavli institute for theoretical physics China,Chinese Academy of Sciences,Beijing 100190,China 2Key Laboratory of Frontiers in theoretical physics,institute of theoretical physics,Chinese Academy of Sciences,Beijing 100190,China 3Interdisciplinary Center for theoretical Study,University of Science and Technology of China,Hefei 230026,China 4department of physics,College of Sciences,Northeastern University,Shenyang 110004,China Kavli institute for theoretical physics China Chinese Academy of Sciences Beijing China Key Laboratory of Frontiers in theoretical physics Institute of Theoretical Physics Chinese Academy of Sciences Beijing China Interdisciplinary Center for theoretical Study University of Science and Technology of China Hefei China department of physics College of Sciences Northeastern University Shenyang China

We compare some popular dark energy models under the assumption of a flat universe by using the latest observational data including the type Ia supernovae Constitution compilation,the baryon acoustic oscillation measurement from the Sloan Digital Sky Survey,the cosmic microwave background measurement given by the seven-year Wilkinson Microwave Anisotropy Probe observations and the determination of H0 from the Hubble Space *** comparison statistics such as the Bayesian and Akaike information criteria are applied to assess the worth of the *** statistics favor models that give a good fit with fewer *** on this analysis,we find that the simplest cosmological constant model that has only one free parameter is still preferred by the current *** other dynamical dark energy models,we find that some of them,such as the αdark energy,constant w,generalized Chaplygin gas,Chevalliear-Polarski-Linder parametrization,and holographic dark energy models,can provide good fits to the current data,and three of them,namely,the Ricci dark energy,agegraphic dark energy,and Dvali-Gabadadze-Porrati models,are clearly disfavored by the data.

关键词： dark energy models observational constraints model comparison information criteria