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Chinese Physics B 2024年第4期33卷 129-134页

作者：张雅芃姚嘉文刘正东马作霖仲佳勇 department of astronomy Beijing Normal UniversityBeijing 100875China institute for frontiers in astronomy and astrophysics Beijing Normal UniversityBeijing 102206China

Magnetic reconnection of the self-generated magnetic fields in laser-plasma interaction is an important laboratory method for modeling high-energy density astronomical and astrophysical phenomena.We use the Martin-Puplett interferometer(MPI)polarimeter to probe the peripheral magnetic fields generated in the common magnetic reconnection configuration,two separated coplanar plane targets,in laser-target interaction.We introduce a new method that can obtain polarization information from the interference pattern instead of the sinusoidal function fitting of the intensity.A bidirectional magnetic field is observed from the side view,which is consistent with the magneto-hydro-dynamical(MHD)simulation results of self-generated magnetic field reconnection.We find that the cancellation of reverse magnetic fields after averaging and integration along the observing direction could reduce the magnetic field strength by one to two orders of magnitude.It indicates that imaging resolution can significantly affect the accuracy of measured magnetic field strength.

关键词： laser-plasma experiment polarimeter self-generated magnetic field magnetic reconnection

An Asymmetric Galactic Stellar Disk Traced by OB-type Stars from LAMOST DR7

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Research in astronomy and astrophysics 2024年第6期24卷 40-53页

作者： Xiaopeng Liu Hao Tian Wenyuan Cui Linlin Li Jiaming Liu Zhenyan Huo Yawei Gao department of Physics Hebei Normal University Guo Shoujing institute for astronomy Hebei Normal University Key Laboratory of Space astronomy and Technology National Astronomical Observatories Chinese Academy of Sciences institute for frontiers in astronomy and astrophysics Beijing Normal University

Using 9943 OB-type stars from LAMOST DR7 in the solar neighborhood,we fit the vertical stellar density profile with the model including a single exponential distribution at different positions （R,Φ）.The distributions of the scale heights and scale length show that the young disk traced by the OB-type stars is not axisymmetric.The scale length decreases versus the azimuthal angle Φ,i.e.,from.■kpc withΦ=-3°to■kpc withΦ=9°.Meanwhile we find signal of non-symmetry in the distribution of the scale height of the north and south of the disk plane.The scale height in the north side shows signal of flaring of the disk,while that of the south disk stays almost constant around hs=130 pc.The distribution of the displaceeent of the disk plane Z0also shows variance versus the azimuthal angleΦ,which displays significant differences with the warp model constrained by the Cepheid stars.We also test different values for the position of the Sun,and the distance between the Sun and the Galactic center affects the scale heights and the displacement of the disk significantly,but that does not change our conclusion that the disk is not axisymmetric.

关键词： galaxies: spiral Galaxy: disk stars: early-type stars: massive

Accuracy of numerical relativity waveforms with respect to space-based gravitational wave detectors

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Communications in Theoretical Physics 2024年第1期76卷 82-95页

作者： Zun Wang Junjie Zhao Zhoujian Cao institute for frontiers in astronomy and astrophysics Beijing Normal UniversityBeijing 102206China department of astronomy Beijing Normal UniversityBeijing 100875China School of Fundamental Physics and Mathematical Sciences Hangzhou Institute for Advanced StudyUCASHangzhou 310024China

As with the laser interferometer gravitational-wave observatory(LIGO),the matched filtering technique will be critical to the data analysis of gravitational wave detection by space-based detectors,including LISA,Taiji and Tianqin.Waveform templates are the basis for such matched filtering techniques.To construct ready-to-use waveform templates,numerical relativity waveforms are a starting point.Therefore,the accuracy issue of numerical relativity waveforms is critically important.There are many investigations regarding this issue with respect to LIGO.But unfortunately there are few results on this issue with respect to space-based detectors.The current paper investigates this problem.Our results indicate that the existing numerical relativity waveforms are as accurate as 99%with respect to space-based detectors,including LISA,Taiji and Tianqin.Such an accuracy level is comparable to that with respect to LIGO.

关键词： numerical relativity gravitational wave binary black hole

Optical Extinctions of Inter-Arm Molecular Clouds in M31: A Pilot Study for the Upcoming CSST Observations

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Research in astronomy and astrophysics 2024年第6期24卷 325-335页

作者： Cailing Chen Zheng Zheng Chao-Wei Tsai Sihan Jiao Jing Tang Jingwen Wu Di Li Yun Zheng Linjing Feng Yujiao Yang Yuan Liang National Astronomical Observatories Chinese Academy of Sciences University of Chinese Academy of Sciences Key Laboratory of Radio astronomy and Technology Chinese Academy of Sciences institute for frontiers in astronomy and astrophysics Beijing Normal University Zhejiang Lab

Recent submillimeter dust thermal emission observations have unveiled a significant number of inter-arm massive molecular clouds in M31. However, the effectiveness of this technique is limited to its sensitivity, making it challenging to study more distant galaxies. This study introduces an alternative approach, utilizing optical extinctions derived from space-based telescopes, with a focus on the forthcoming China Space Station Telescope（CSST）. We first demonstrate the capability of this method by constructing dust extinction maps for 17 inter-arm massive molecular clouds in M31 using the Panchromatic Hubble Andromeda Treasury data. Our analysis reveals that inter-arm massive molecular clouds with an optical extinction（AV） greater than 1.6 mag exhibit a notable AVexcess, facilitating their identification. The majority of these inter-arm massive molecular clouds show an AVaround 1 mag, aligning with measurements from our JCMT data. Further validation using a mock CSST RGB star catalog confirms the method's effectiveness. We show that the derived AVvalues using CSST z and y photometries align more closely with the input values. Molecular clouds with AV> 1.6 mag can also be identified using the CSST mock data. We thus claim that future CSST observation clouds provide an effective way for the detection of inter-arm massive molecular clouds with significant optical extinction in nearby galaxies.

关键词： Galaxy: structure infrared: stars ISM: clouds

Quantitative Analysis of Seeing with Height and Time at Muztagh-Ata Site Based on ERA5 Database

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Research in astronomy and astrophysics 2024年第1期24卷 87-95页

作者： Xiao-Qi Wu Cun-Ying Xiao Ali Esamdin Jing Xu Ze-Wei Wang Luo Xiao institute for frontiers in astronomy and astrophysics Beijing Normal UniversityBeijing 102206China department of astronomy Beijing Normal UniversityBeijing 100875China Xinjiang Astronomical Observatory Chinese Academy of SciencesUrumqi 830011China University of Chinese Academy of Sciences Beijing 100049China

Seeing is an important index to evaluate the quality of an astronomical site.To estimate seeing at the Muztagh-Ata site with height and time quantitatively,the European Centre for Medium-Range Weather Forecasts reanalysis database(ERA5)is used.Seeing calculated from ERA5 is compared consistently with the Differential Image Motion Monitor seeing at the height of 12 m.Results show that seeing decays exponentially with height at the Muztagh-Ata site.Seeing decays the fastest in fall in 2021 and most slowly with height in summer.The seeing condition is better in fall than in summer.The median value of seeing at 12 m is 0.89 arcsec,the maximum value is1.21 arcsec in August and the minimum is 0.66 arcsec in October.The median value of seeing at 12 m is 0.72arcsec in the nighttime and 1.08 arcsec in the daytime.Seeing is a combination of annual and about biannual variations with the same phase as temperature and wind speed indicating that seeing variation with time is influenced by temperature and wind speed.The Richardson number Ri is used to analyze the atmospheric stability and the variations of seeing are consistent with Ri between layers.These quantitative results can provide an important reference for a telescopic observation strategy.

关键词： site testing atmospheric effects methods:data analysis telescopes Earth

Scintillation Arc from FRB 20220912A

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Science China(Physics,Mechanics & astronomy) 2024年第1期67卷 134-142页

作者： Zi-Wei Wu Robert AMain Wei-Wei Zhu Bing Zhang Peng Jiang Jia-Rui Niu Jin-Lin Han Di Li Ke-Jia Lee Dong-Zi Li Yuan-Pei Yang Fa-Yin Wang Rui Luo Pei Wang Chen-Hui Niu Heng Xu Bo-Jun Wang Wei-Yang Wang Yong-Kun Zhang Yi Feng De-Jiang Zhou Yong-Hua Xu Can-Min Deng Yu-Hao Zhu National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China Max-Planck-Institut für Radioastronomie Bonn 53121Germany institute for Frontier in astronomy and astrophysics Beijing Normal UniversityBeijing 102206China Nevada Center for astrophysics and department of Physics and astronomy University of NevadaLas VegasNV 89154USA CAS Key Laboratory of FAST National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China School of astronomy University of Chinese Academy of SciencesBeijing 100049China NAOC-UKZN Computational astrophysics Centre University of KwaZulu-NatalDurban 4000South Africa department of astronomy Peking UniversityBeijing 100871China Kavli institute for astronomy and astrophysics Peking UniversityBeijing 100871China Cahill Center for astronomy and astrophysics California Institute of TechnologyPasadena 91125USA South-Western institute For astronomy Research Yunnan UniversityKunming 650504China School of astronomy and Space Science Nanjing UniversityNanjing 210093China Key Laboratory of Modern astronomy and astrophysics(Nanjing University) Ministry of EducationNanjing 210023China CSIRO Space and astronomy Epping 1710Australia department of astronomy School of Physics and Materials ScienceGuangzhou UniversityGuangzhou 510006China Research Center for Intelligent Computing Platforms Zhejiang LaboratoryHangzhou 311100China Yunnan Observatories Chinese Academy of SciencesKunming 650011China Guangxi Key Laboratory for Relativistic astrophysics Department of PhysicsGuangxi UniversityNanning 530004China

We present the interstellar scintillation analysis of fast radio burst(FRB)20220912A during its extremely active episode in 2022using data from the Five-hundred-meter Aperture Spherical Radio Telescope(FAST).We detect a scintillation arc in the FRB’s secondary spectrum,which describes the power in terms of the scattered FRB signals’time delay and Doppler shift.The arc indicates that the scintillation is caused by a highly localized region.Our analysis favors a Milky Way origin of the ionized interstellar medium(IISM)for the localized scattering medium but cannot rule out a host galaxy origin.We present our method for detecting the scintillation arc,which can be applied generally to sources with irregularly spaced bursts or pulses.These methods could help shed light on the complex interstellar environment surrounding the FRBs and in our Galaxy.

关键词： fast radio burst scintillation FRB 20220912A

Microlensing bias on the detection of strong lensing gravitational wave

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Science China(Physics,Mechanics & astronomy) 2024年第6期67卷 156-165页

作者： Xikai Shan Xuechun Chen Bin Hu Guoliang Li institute for Frontier in astronomy and astrophysics Beijing Normal UniversityBeijing 102206China department of astronomy Beijing Normal UniversityBeijing 100875China Purple Mountain Observatory Chinese Academy of SciencesNanjing 210023China

Identifying strong lensing gravitational wave(SLGW)events is of utmost importance in astrophysics as we approach the historic first detection of SLGW amidst the growing number of gravitational wave(GW)events.Currently,one crucial method for identifying SLGW signals involves assessing the overlap of parameters between two GWs.However,the distribution of discrete matter,such as stars and sub-halos,within the strong lensing galaxy can imprint a wave optical(WO)effect on the SLGW waveform.These frequency dependent imprints introduce biases in parameter estimation and impact SLGW identification.In this study,we assess the influence of the stellar microlensing field embedded in a strong lensing galaxy.Our findings demonstrate that the WO effect reduces the detection efficiency of SLGW by 5%-50%for various false alarm probabilities per pair(FAPper pair).Specifically,at an FAPper pairof 10^(-5),the detection efficiency decreases from~10%to~5%.Consequently,the presence of the microlensing field can result in missing half of the strong lensing candidates.Additionally,the microlensing WO effect introduces a noticeable bias in intrinsic parameters,particularly for chirp mass and mass ratio.However,it has tiny influence on extrinsic parameters.Considering all parameters,~30%of events exhibit a 1σparameter bias,~12%exhibit a 2σparameter bias,and~5%exhibit a 3σparameter bias.

关键词： gravitational wave gravitational strong lensing gravitational micro lensing wave optical effect

Capture Efficiency Analysis in the Circular Restricted Three-body Problem

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Research in astronomy and astrophysics 2024年第5期24卷 198-210页

作者： Yu-Xuan Miao Xi-Yun Hou department of astronomy and Space Science Nanjing UniversityNanjing 210023China institute of Space Environment and Astrodynamics Nanjing UniversityNanjing 210023China Key Laboratory of Modern astronomy and astrophysics Ministry of EducationNanjing 210023China

Temporary capture efficiency is studied in the framework of the circular restricted three-body problem in two steps.First, a non-uniform distribution of test particles around the secondary's orbit is obtained by fully accounting the secondary's gravitational influence. Second, the capture efficiency is computed based on the non-uniform distribution. Several factors influencing the result are discussed. By studying the capture efficiency in the circular restricted three-body problem of different mass ratios, a power-law relation between the capture efficiency(p) and the mass ratio(μ) is established, which is given by p ≈ 0.27 × μ^(0.53), within the range of 3.0035 ×10^(-6)≤ μ ≤ 3.0034 × 10^(-5). Taking the Sun–Earth system as an example, the influence from the orbit eccentricity of the secondary on the non-uniform distribution and the capture efficiency is studied. Our studies find that the secondary's orbit eccentricity has a negative influence on the capture efficiency.

关键词： methods numerical-celestial mechanics-planets and satellites dynamical evolution and stability

HiFAST:An HIdata calibration and imaging pipeline for FAST

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Science China(Physics,Mechanics & astronomy) 2024年第5期67卷 182-199页

作者： Yingjie Jing Jie Wang Chen Xu Ziming Liu Qingze Chen Tiantian Liang Jinlong Xu Yixian Cao Jing Wang Huijie Hu Chuan-Peng Zhang Qi Guo Liang Gao Mei Ai Hengqian Gan Xuyang Gao Jinlin Han Ligang Hou Zhipeng Hou Peng Jiang Xu Kong Fujia Li Zerui Liu Li Shao Hengxing Pan Jun Pan Lei Qian Jinghai Sun Ningyu Tang Qingliang Yang Bo Zhang Zhiyu Zhang Ming Zhu National Astronomical Observatories Chinese Academy of SciencesBeijing 100012China institute for frontiers in astronomy and astrophysics Beijing Normal UniversityBeijing 02206China School of astronomy and Space Science University of Chinese Academy of SciencesBeijing 100049China Guizhou Radio Astronomical Observatory Guizhou UniversityGuiyang 55000China Max Planck institute for Extraterrestrial Physics Garching 85748Germany Kavli institute for astronomy and astrophysics Peking UniversityBeijing 100871China institute of Computational Cosmology Department of PhysicsUniversity of DurhamDurham DHI 3LEUK CAS Key Laboratory of FAST National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China Deep Space Exploration Laboratory/department of astronomy University of Science and Technology of ChinaHefei 230026China School of astronomy and Space Science University of Science and Technology of ChinaHefei 230026China astrophysics Department of PhysicsUniversity of OxfordOxford OX/3RHUK College of Earth Sciences Guilin University of TechnologyGuilin 541004China department of Physics Anhui Normal UniversityWuhu 241002China School of astronomy and Space Science Nanjing UniversityNanjing 210023China Key Laboratory of Modern astronomy and astrophysics Nanjing UniversityNanjing 20023China

The Five-hundred-meter Aperture Spherical radio Telescope(FAST)has the largest aperture and a 19-beam L-band receiver,making it powerful for investigating the neutral hydrogen atomic gas(HI)in the universe.We present HiFAST(https://hifast.***.io),a dedicated,modular,and self-contained calibration and imaging pipeline for processing the H?data of FAST.The pipeline consists of frequency-dependent noise diode calibration,baseline fitting,standing wave removal using an FFT-based method,flux density calibration,stray radiation correction,and gridding to produce data cubes.These modules can be combined as needed to process the data from most FAST observation modes:tracking,drift scanning,On-The-Fly mapping,and most of their variants.With HiFAST,the root-mean-square(RMS)noises of the calibrated spectra from all 19 beams were only slightly(~5%)higher than the theoretical expectation.The results for the extended source M33 and the point sources are consistent with the results from Arecibo.The moment maps(0,1 and 2)of M33 agree well with the results from the Arecibo Galaxy Environment Survey(AGES)with a fractional difference of less than 10%.For a common sample of 221 sources with signal-to-noise ratio S/N>10 from the Arecibo Legacy Fast ALFA(ALFALFA)survey,the mean value of fractional difference in the integrated flux density,Sint,between the two datasets is approximately 0.005%,with a dispersion of 15.4%.Further checks on the integrated flux density of 23 sources with seven observations indicate that the variance in the flux density of the source with luminous objects(Sint>2.5 Jy km s-1)is less than 5%.Our tests suggest that the FAST telescope,with the efficient,precise,and user-friendly pipeline HiFAST,will yield numerous significant scientific findings in the investigation of the H?in the universe.

关键词： fractional luminous correction

Dynamical Dark Energy in Light of Cosmic Distance Measurements. Ⅱ. A Study Using Current Observations

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Research in astronomy and astrophysics 2024年第6期 17-22页

作者： Xiaoma Wang Gan Gu Xiaoyong Mu Shuo Yuan Gong-Bo Zhao National Astronomical Observatories Chinese Academy of Sciences University of Chinese Academy of Sciences institute for frontiers in astronomy and astrophysics Beijing Normal University

We extract key information on dark energy from current observations of BAO, OHD and H0, and find hints of dynamical behavior of dark energy. In particular, a dynamical dark energy model whose equation of state crosses-1 is favored by observations. We also find that the Universe has started accelerating at a lower redshift than expected.

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