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Wave effect of gravitational waves intersected with a microlens field Ⅱ:An adaptive hierarchical tree algorithm and population study

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Science China(Physics,Mechanics & Astronomy) 2025年第1期Mechanics & Astronomy) .卷 241-254页

作者： Xikai Shan Guoliang Li Xuechun Chen Wen Zhao Bin Hu Shude Mao Department of Astronomy Tsinghua University purple Mountain observatory Chinese Academy of Sciences Institute for Frontier in Astronomy and Astrophysics Beijing Normal University School of Physics and Astronomy Beijing Normal University School of Astronomy and Space Science University of Science and Technology of China CAS Key Laboratory for Researches in Galaxies and Cosmology Department of Astronomy University of Science and Technology of ChinaChinese Academy of Sciences

The gravitational lensing wave effect generated by a microlensing field embedded in a lens galaxy is an inevitable phenomenon in strong lensed gravitational waves （SLGWs）.This effect presents both challenges and opportunities for the detection and application of ***,investigating this wave effect requires computing a complete diffraction integral over each microlens in the *** is extremely time-consuming due to the large number of microlenses （10～3-10～6）.Therefore,simply adding all the microlenses is ***,the complexity of the time delay surface makes the lens plane resolution a crucial factor in controlling numerical *** this paper,we propose a trapezoid approximation-based adaptive hierarchical tree algorithm to meet the challenges of calculation speed and *** find that this algorithm accelerates the calculation by four orders of magnitude compared to the simple adding method and is one order of magnitude faster than the fixed hierarchical tree algorithm proposed for electromagnetic *** importantly,our algorithm ensures controllable numerical errors,increasing confidence in the *** with our previous work （***.66,239511,2023）,this paper addresses all numerical issues,including integral convergence,precision,and computational time1).Finally,we conducted a population study on the microlensing wave effect of SLGWs using this algorithm and found that the microlensing wave effect cannot be ignored,especially for Type II SLGWs （from saddle position of the time delay surface） due to their intrinsic geometric structures and their typical intersection with a denser microlensing ***,more than 33%（11%） of SLGWs have a mismatch larger than 1%（3%） compared to the unlensed ***,we found that the mismatch between signal pairs in a doubly imaged GW is generally larger than 10-3,and 61%（25%） of signal pairs have a mismatch larger than 1%（3%）.Therefo

关键词： gravitational lensing diffractional integral algorithm gravitational wave

Two-post-Newtonian approximation of the scalar-tensor theory with an intermediate-range force for general matter

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Science China(Physics,Mechanics & Astronomy) 2015年第3期58卷 8-15页

作者： DENG XueMei purple Mountain observatory Chinese Academy of Sciences

Some future space missions measure distances of laser links and angles with unprecedented precision, allowing us to test theories of gravity up to the two-post-Newtonian （2PN） order. Besides, investigation of an intermediate-range force has been of considerable interests in gravitational experiments. Inspired by these ideas, within the framework of the scalar-tensor theory with an intermediate- range force, its 2PN approximation is obtained with Chandrasekhar＇s approach. It includes the 2PN metric and equations of motion for general matter without specific equation of state. The conserved quantities to the 2PN order are isolated with the aid of the energy-momentum complex. We also discuss the prospect of testing and distinguishing the intermediate-range force with the orbital motions of celestial bodies and spaeecrafts.

关键词： gravitation intermediate-range force post-Newtonian approximation

Dispersion Equation of Low-Frequency Waves Driven by Temperature Anisotropy

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Plasma Science and Technology 2012年第10期14卷 880-885页

作者：陈玲吴德金 purple Mountain observatory Chinese Academy of Sciences

The plasma temperature （or the kinetic pressure） anisotropy is an intrinsic characteristic of a collisionless magnetized plasma. In this paper, based on the two-fluid model, a dispersion equation of low-frequency （ω〈〈ωci, ωci the ion gyrofrequency） waves, including the plasma temperature anisotropy effect, is presented. We investigate the properties of low-frequency waves when the parallel temperature exceeds the perpendicular temperature, and especially their dependence on the propagation angle, pressure anisotropy, and energy closures. The results show that both the instable Alfven and slow modes are purely growing. The growth rate of the Alfven wave is not affected by the propagation angle or energy closures, while that of the slow wave depends sensitively on the propagation angle and energy closures as well as pressure anisotropy. The fast wave is always stable. We also show how to elaborate the symbolic calculation of the dispersion equation performed using Mathematica Notebook.

关键词： dispersion equation low-frequency waves temperature anisotropy

A method of autonomous orbit determination for satellite using star sensor

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Science China(Physics,Mechanics & Astronomy) 2005年第3期48卷 268-281页

作者： MA Jianbo XU Jin CAO Zhibin purple Mountain observatory Chinese Academy of Sciences Nanjing 210008 China Purple Mountain Observatory Chinese Academy of Sciences Nanjing 210008 China Purple Mountain Observatory Chinese Academy of Sciences Nanjing 210008 China

In this paper a method of autonomous orbit determination using star sensor is studied. By building relatively consummate dynamical models which simulate attitude motion of satellite and observation from satellite to background stars, the simulant computation of this method is executed, and it is shown that the method of autonomous orbit determination is feasible. Academic and calculation analyses have been done for the relation between the direction of star sensor with respect to satellite-body coordinate system and the accuracy of autonomous orbit determination.

关键词： autonomous orbit determination of satellite, star sensor, attitude of satellite.

The investigation of the Neupert effect in two solar flares

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Science China(Physics,Mechanics & Astronomy) 2009年第11期52卷 1686-1690页

作者： NING ZongJun purple Mountain observatory, Nanjing 210008, China purple Mountain observatory Nanjing China

The Neupert effect suggests a flare model in which the nonthermal emissions are produced by energetic electrons which heat lower corona and chromosphere to produce the thermal emissions. Based on this concept, we investigate the Neupert effect to test the correlation between the hard X-ray spectral index and the time rate of the UV flare area at 1600 or 171 . Using the T RACE and RHESSI observations, we explore these quantities for two solar flares, one on March 14, 2002 and the other on November 1, 2003. The negative dependence between the spectral index and the time rate of the UV flare area is found, especially during the hard X-ray sub-peaks. This finding indicates that the electron-beam-driven heating plays a prominent role in the UV emission of these two flares.

关键词： solar flares UV radiation X-rays

The structure of molecular cloud W51 and dense cores——CO(J=1-0)and HCO^+(J=1-0)spectral line mapping

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Science China(Physics,Mechanics & Astronomy) 2005年第2期48卷 168-177页

作者： MA Hongjun PEI Chunchuan ZENG Qin purple Mountain observatory Chinese Academy of Sciences Nanjing 210008 China Purple Mountain Observatory Chinese Academy of Sciences Nanjing 210008 China Purple Mountain Observatory Chinese Academy of Sciences Nanjing 210008 China

We present a large scale map of about 15′×15′of CO(J=1-0) toward W51 giant molecular cloud (GMC), which covers the most active star-forming region of W51 GMC, and an interferometry HCO+(J=1-0) map of a high spatial resolution (i.e. 8″.7× 6″.1) with a field of view (2′×2′) centered at W51IRS1. A structure model of W51GMC is obtained according to the results of the observations and analyses. The observations demonstrate that some small molecular cores generated by the collision between the W51GMC and the 60—73 km·s-1 foreground cloud are collapsing toward their own centers. In addition, 16 new molecular cores are discovered from the HCO+(J=1-0) map.

关键词： molecular core, continuum source, star formation.

Near-Infrared observations of the Massive Star Forming Region IRAS 23151+5912

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Chinese Journal of Astronomy and Astrophysics 2004年第3期4卷 284-298页

作者： Xue-Peng Chen Yong-Qiang Yao purple Mountain observatory Chinese Academy of Sciences, Nanjing 210008 purple Mountain observatory Chinese Academy of Sciences Nanjing 210008

Near-infrared images and K-band spectroscopy of the massive star-formingregion IRAS 23151+5912 are presented. The JHK′ images reveal an embedded infrared clusterassociated with infrared nebula, and the H_2 (2.12 μm) narrowband image provides for the first timeevidence of outflow activity associated with the cluster. That the cluster is young can be shown bythe high percentage of infrared excess sources and the outflow activity. We suggest an age of thecluster of ～ 10~6 yr. Eight young stars are found in the bright nebular core around IRAS23151+5912. By the color-magnitude diagrams of the cluster, we found five high-mass YSOs and fourintermediate-mass YSOs in the cluster. Eight H_2 emission features are discovered in the region witha scattered and non-axisymmetric distribution, indicating the existence of multiple outflows drivenby the cluster. Diffuse H_2 emission detected to the north and to the west of the cluster mayresult from UV leakage of the cluster. Brγ, H_2, and CIV emission lines are found in the K-bandspectrum of the brightest source, NIRS 19, indicating the presence of envelope, stellar wind, andshock in the circumstellar environment. We have estimated an O7-O9 spectral type for the centralmassive YSO (20 ～ 30 solar mass), with an age of less than 1 x 10~6 yr.

关键词： infrared radiation stars: formation ISM: individual: IRAS 23151 + 5912 ISM: jets and outflows

The total column densities and fractional abundances of CH_3CN,CH_3OH,HCOOCH_3 and^(13)CS in W51 cores

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Science China(Physics,Mechanics & Astronomy) 2005年第2期48卷 158-167页

作者： PEI Chunchuan MA Hongjun ZENG Qin LI Bo purple Mountain observatory Chinese Academy of Sciences Nanjing 210008 China Purple Mountain Observatory Chinese Academy of Sciences Nanjing 210008 China Purple Mountain Observatory Chinese Academy of Sciences Nanjing 210008 China Purple Mountain Observatory Chinese Academy of Sciences Nanjing 210008 China

We present interferometric observations of the W51 region at 2.7 mm and 3.3 mm with the Berkeley-Illinois-Maryland Association Array. The lines of CH3CN (J = 6 – 5, K = 0,1,2,3,4), CH3OH (15-2 ?151 E), HCOOCH3-A (71,6 – 61,5), HCOOCH3 -E (71,6 – 61,5) and 13CS (2-1) as well as the 2.7 mm continuum toward W51 have been observed. The derived total beam-averaged column densities NT and fractional abundances of CH3CN, CH3OH, HCOOCH3 and 13CS in W51 cores have been obtained.

关键词： massive star formation, interstellar molecular lines, column density, fractional abundance.

How to co-add images? I. A new iterative method for image reconstruction of dithered observations

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Research in Astronomy and Astrophysics 2017年第10期17卷 1-14页

作者： Lei Wang Guo-Liang Li purple Mountain observatory Chinese Academy of Sciences

By employing the previous Voronoi approach and replacing its nearest neighbor approx- imation with Drizzle in iterative signal extraction, we develop a fast iterative Drizzle algorithm, namedfiDrizzle, to reconstruct the underlying band-limited image from undersampled dithered frames. Compared with the existing iDrizzle, the new algorithm improves rate of convergence and accelerates the computational speed. Moreover, under the same conditions （e.g. the same number of dithers and iterations）, fiDrizzle can make a better quality reconstruction than iDrizzle, due to the newly discov- ered High Sampling caused Decelerating Convergence （HSDC） effect in the iterative signal extraction *** demonstrates its powerful ability to perform image deconvolution from undersampled dithers.

关键词： techniques: image processing -- methods: observational -- stars: imaging -- planets andsatellites: detection -- gravitational lensing