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Evolution of High-energy Electron Distribution in Pulsar Wind Nebulae

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research in Astronomy and Astrophysics 2024年第7期24卷 198-214页

作者： Yi-Ming Liu Hou-Dun Zeng Yu-Liang Xin Si-Ming Liu Yi Zhang 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 School of Physical Science and Technology Southwest Jiaotong UniversityChengdu 610031China

In this paper,we analyze the spectral energy distributions of 17 powerful(with a spin-down luminosity greater than10~(35)erg s~(-1))young(with an age less than 15,000 yr)pulsar wind nebulae(PWNe)using a simple timein-dependent one-zone emission *** aim is to investigate correlations between model parameters and the ages of the corresponding PWNe,thereby revealing the evolution of high-energy electron distributions within *** findings are as follows:(1)The electron distributions in PWNe can be characterized by a double power-law with a super-exponential cutoff.(2)As PWNe evolve,the high-energy end of the electron distribution spectrum becomes harder with the index decreasing from approximately 3.5 to 2.5,while the low-energy end spectrum index remains constant near 1.5.(3)There is no apparent correlation between the break energy or cutoff energy and the age of PWNe.(4)The average magnetic field within PWNe decreases with age,leading to a positive correlation between the energy loss timescale of electrons at the break energy or the high-energy cutoff and the age of the PWN.(5)The total electron energy within PWNe remains constant near 2×10~(48)erg,while the total magnetic energy decreases with age.

关键词： radiation mechanisms non-thermal-ISM general-ISM supernova remnants-gamma-rays general

The siphonic energy transfer between hot solar wind and cold martian ionosphere through open magnetic flux rope

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Fundamental research 2024年第4期4卷 882-889页

作者： Xiaojun Xu Lou-Chuang Lee Qi Xu Qing Chang Jing Wang Ming Wang Shaosui Xu Christian Mosti Charles J.Farrugia Xing Wang Yudong Ye Zilu Zhou Lei Luo Peishan He Shaoguan Cheng State Key laboratory of Lunar and Planetary Sciences Macao University of Science and TechnologyMacao 999078China CNSA Macao Center for space Exploration and Science Macao 999078China Institute of Earth Science Academia SinicaTaipei 115029China Institute of space Science and Applied Technology Harbin Institute of TechnologyShenzhen 518000China Planetary Environmental and Astrobiological research laboratory(PEARL) School of Atmospheric SciencesSun Yat-sen UniversityZhuhai 519000China Nanjing University of Information Science and Technology Nanjing 210000China space Sciencelaboratory Universityof CaliforniaBerkeleyCA94320USA space research Institute Austrian Academy of SciencesGraz 8010Austria University of New Hampshire NH 03824USA

A mechanism for energy transfer from the solar wind to the Martian ionosphere through open magnetic flux rope is proposed based on the observations by Mars Atmosphere and Volatile EvolutioN(MAVEN).The satellite was located in the dayside magnetosheath at an altitude of about 70o km above the northern *** between the hot solar wind protons and the cold heavy ions/neutrals in the subsolar region can cool the protons and heat the heavy *** a result,the magnetosheath protons are siphoned into the ionosphere due to the thermal pressure gradient of protons and the heated heavy ions escape along the open magnetic field *** direct collisions in the lower-altitude region were not detected,this physical process is demonstrated by MAVEN measurements of enhanced proton density,decreased proton temperature and oppositely directed motions of hot and cool protons within the flux rope,which are very different from the observational features of the flux transfer events near the Earth's *** mechanism could universally exist in many contexts where a collisionless plasma region is connected to a collisional plasma *** reconstructing the magnetic geometry and the cross-section of the flux rope using the Grad-Shafranov technique,the ion loss rates are quantitatively estimated to be on the order of 1023 s-l,which is much higher than previously estimated.

关键词： Mars Flux rope Solarwind Ionosphere Ion loss

Super-resolution Imaging of Telescopic Systems based on Optical-neural Network Joint Optimization

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research in Astronomy and Astrophysics 2024年第9期24卷 167-177页

作者： You-Hong Sun Tao Zhang Hao-Dong Shi Qiang Fu Jia-Nan Liu Kai-Kai Wang Chao Wang research Institute of Chongqing Changchun University of Science and TechnologyChangchun 130022China National and Local Joint Engineering research Center for space Photoelectric Technology Changchun University of Science and TechnologyChangchun 130022China The Institute of Remote Sensing Satellites China Academy of Space Technology(CAST)Beijing 100094China

Optical telescopes are an important tool for acquiring optical information about distant objects,and resolution is an important indicator that measures the ability to observe object ***,due to the effects of system aberration,atmospheric seeing,and other factors,the observed image of ground-based telescopes is often degraded,resulting in reduced *** paper proposes an optical-neural network joint optimization method to improve the resolution of the observed image by co-optimizing the point-spread function(PSF)of the telescopic system and the image super-resolution(SR)*** improve the speed of image reconstruction,we designed a generative adversarial net(LCR-GAN)with light parameters,which is much faster than the latest unsupervised *** reconstruct the PSF trained by the network in the optical path,a phase mask is *** improves the image reconstruction effect of LCR-GAN by reconstructing the PSF that best matches the *** results of simulation and verification experiments show that compared with the pure deep learning method,the SR image reconstructed by this method is rich in detail and it is easier to distinguish stars or stripes.

关键词： Techniques:image processing Telescopes Stars:imaging

Study on the Performance of the GRANDProto300 Particle Detector Array by Simulation

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research in Astronomy and Astrophysics 2024年第1期24卷 173-177页

作者： Fu-Lin Dai Quan-Bu Gou Xiaoyuan Huang Yi-Qing Guo 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 Key laboratory of Particle Astrophysics Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China University of Chinese Academy of Sciences Beijing 100049China

The Giant Radio Array for Neutrino Detection(GRAND)is a proposed large-scale observatory designed to detect cosmic rays,gamma-rays,and neutrinos with energies exceeding 100 Pe *** GRANDProto300 experiment is proposed as the early stage of the GRAND project,consisting of a hybrid array of radio antennas and scintillator *** latter,as a mature and traditional detector,is used to cross-check the nature of the candidate events selected from radio *** this study,we developed a simulation software called G4GRANDProto300,based on the Geant4 software package,to optimize the spacing of the scintillator detector array and to investigate its effective *** analysis was conducted at various zenith angles under different detector spacings,including 300,500,600,700,and 900 *** results indicate that,for large zenith angles used to search for cosmic-ray in the GRAND project,the optimized effective area is with a detector spacing of 500 *** G4GRANDProto300 software that we developed could be used to further optimize the layout of the particle detector array in future work.

关键词： astroparticle physics instrumentation:detectors (ISM:)cosmic rays

Investigations of nuclear chirality at iThemba LABS

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Frontiers of physics 2024年第2期19卷 7-38页

作者： R.A.Bark E.A.Lawrie C.Liu S.Y.Wang iThemba laboratory for Accelerator Based Sciences National Research FoundationP.O.Box 722Somerset-West 7129South Africa Department of Physics University of the Western CapePrivate Bag X177535BellvilleSouth Africa Shandong Provincial Key laboratory of Optical Astronomy and Solar-Terrestrial Environment Institute of Space SciencesShandong UniversityWeihai 264209China

Progress in the studies of chirality in atomic nuclei at iThemba LABS is *** regions of chirality,around mass 80 and 190 have been discovered using the AFRODITE array,specifically in the nuclei^(74)As,^(78,80,82)Br,^(81)Kr,and^(193,194,198)*** phenomena have been observed,including multiple chiral bands in the same nucleus,the coexistence of octupole correlations and nuclear chirality,and the coexistence of pseudo spin and nuclear *** best example of chiral degeneracy to date was found in ^(194)*** level scheme of ^(106)Ag has been revisited and interpreted in terms of two-and four-quasiparticle *** using the particle-rotor model have shown that the fingerprints of chirality in the two-quasiparticle system only can occur in an idealised model *** systems with a higher number of quasiparticles,the calculations showed that nuclear chirality can persist.

关键词： chirality high-spin states particle-rotor model

Thiamine-modified metabolic reprogramming of human pluripotent stem cell-derived cardiomyocyte under space microgravity

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Signal Transduction and Targeted Therapy 2024年第5期9卷 2132-2142页

作者： Xinglong Han Lina Qu Miao Yu Lingqun Ye Liujia Shi Guangfu Ye Jingsi Yang Yaning Wang Hao Fan Yong Wang Yingjun Tan Chunyan Wang Qi Li Wei Lei Jianghai Chen Zhaoxia Liu Zhenya Shen Yinghui Li Shijun Hu Department of Cardiovascular Surgery of the First Affiliated Hospital&Institute for Cardiovascular Science State Key Laboratory of Radiation Medicine and ProtectionSuzhou Medical CollegeSoochow UniversitySuzhouChina State Key laboratory of space Medicine China Astronaut Research and Training CenterBeijingChina Department of Hand Surgery Union HospitalTongji Medical CollegeHuazhong University of Science and TechnologyWuhanChina

During spaceflight,the cardiovascular system undergoes remarkable adaptation to microgravity and faces the risk of cardiac ***,the effects and mechanisms of microgravity on cardiac morphology,physiology,metabolism,and cellular biology need to be further *** China started constructing the China space Station(CSS)in 2021,we have taken advantage of the Shenzhou-13 capsule to send human pluripotent stem cell-derived cardiomyocytes(hPSC-CMs)to the Tianhe core module of the *** this study,hPSC-CMs subjected to space microgravity showed decreased beating rate and abnormal intracellular calcium *** and transcriptomic analyses revealed a battery of metabolic remodeling of hPSC-CMs in spaceflight,especially thiamine *** microgravity condition blocked the thiamine intake in *** decline of thiamine utilization under microgravity or by its antagonistic analog amprolium affected the process of the tricarboxylic acid *** decreased ATP production,which led to cytoskeletal remodeling and calcium homeostasis imbalance in *** importantly,in vitro and in vivo studies suggest that thiamine supplementation could reverse the adaptive changes induced by simulated *** study represents the first astrobiological study on the China space Station and lays a solid foundation for further aerospace biomedical *** data indicate that intervention of thiamine-modified metabolic reprogramming in human cardiomyocytes during spaceflight might be a feasible countermeasure against microgravity.

关键词： programming battery modified

A real-time performance improvement method for composite time scale

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Chinese Physics B 2024年第9期33卷 350-357页

作者： Fangmin Wang Wenlin Li Hongfei Dai Chunyi Li Jianhua Zhou Shenhui Xue Bo Wang State Key laboratory of Precision space–time Information Sensing Technology Department of Precision InstrumentTsinghua UniversityBeijing 100084China Key laboratory of Photonic Control Technology(Tsinghua University) Ministry of EducationBeijing 100084China Beijing Satellite Navigation Center Beijing 100094China

The composite time scale(CTS)provides a stable,accurate,and reliable time scale for modern *** improvement of CTS’s real-time performance will improve its stability,which strengths related applications’*** at this goal,a method achieved by determining the optimal calculation interval and accelerating adjustment stage is proposed in this *** determinants of the CTS’s calculation interval(characteristics of the clock ensemble,the measurement noise,the time and frequency synchronization system’s noise and the auxiliary output generator noise floor)are studied and the optimal calculation interval is *** also investigate the effect of ensemble algorithm’s initial parameters on the CTS’s adjustment stage.A strategy to get the reasonable initial parameters of ensemble algorithm is *** results show that the adjustment stage can be finished rapidly or even can be shorten to zero with reasonable initial *** this basis,we experimentally generate a distributed CTS with a calculation interval of 500 s and its stability outperforms those of the member clocks when the averaging time is longer than1700 *** experimental result proves that the CTS’s real-time performance is significantly improved.

关键词： composite time scale real-time performance calculation interval adjustment stage

The anisotropy of suprathermal electrons in the Martian ionosphere

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Earth and Planetary Physics 2024年第3期8卷 459-471页

作者： YuTian Cao Jun Cui XiaoShu Wu WenJun Liang RuiQi Fu HaoYu Lu Planetary Environmental and Astrobiological research laboratory(PEARL) School of Atmospheric SciencesSun Yat-sen UniversityZhuhai 519082China Key laboratory of Geospace Environment University of Science&Technology of ChinaChinese Academy of SciencesHefei 230026China Center for Excellence in Comparative Planetology Chinese Academy of SciencesHefei 230026China School of space and Environment Beihang UniversityBeijing 102206China

Suprathermal electrons are an important population of the Martian ionosphere, either produced by photoionization of atmospheric neutrals or supplied from the Solar Wind (SW). This study is dedicated to an in-depth investigation of the pitch angle distribution of suprathermal electrons at two representative energies, 19−55 eV and 124−356 eV, using the extensive measurements made by the Solar Wind Electron Analyzer on board the Mars Atmosphere and Volatile Evolution. Throughout the study, we focus on the overall degree of anisotropy, defined as the standard deviation of suprathermal electron intensity among different directions which is normalized by the mean omni-directional intensity. The available data reveal the following characteristics: (1) In general, low energy electrons are more isotropic than high energy electrons, and dayside electrons are more isotropic than nightside electrons;(2) On the dayside, the anisotropy increases with increasing altitude at low energies but remains roughly constant at high energies, whereas on the nightside, the anisotropy decreases with increasing altitude at all energies;(3) Electrons tend to be more isotropic in strongly magnetized regions than in weakly magnetized regions, especially on the nightside. These observations indicate that the anisotropy is a useful diagnostic of suprathermal electron transport, for which the conversion between the parallel and perpendicular momenta as required by the conservation of the first adiabatic invariant, along with the atmospheric absorption at low altitudes, are two crucial factors modulating the observed variation of the anisotropy. Our analysis also highlights the different roles on the observed anisotropy exerted by suprathermal electrons of different origins.

关键词： Mars ionosphere suprathermal electron pitch angle distribution

Optical system for extremely large spectroscopic survey telescope

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Science China(Physics,Mechanics & Astronomy) 2024年第7期67卷 158-174页

作者： Ding-qiang Su Hua Bai Xiangyan Yuan Xiangqun Cui Key laboratory of the Ministry of Education School of Astronomy and Space ScienceNanjing UniversityNanjing 210023China Nanjing Institute of Astronomical Optics and Technology(NIAOT) Chinese Academy of SciencesNanjing 210042China University of Chinese Academy of Sciences Nanjing 211135China School of Astronomy and space Science University of Chinese Academy of SciencesBeijing 101408China

This article presents research work on a spectroscopic survey *** idea is as follows:for such a telescope,a pure reflecting optical system is designed,which should have an aperture and a field of view(FOV)both as large as possible and excellent image quality,and then a strip lensm(lens-prism)atmospheric dispersion corrector(S-ADC)is added,only for correcting the atmospheric *** the fund limitation and the simplicity of scaling up,some 12-m telescopes are designed as ***,Korsch,and Meinel put forward the four-mirror Nasmyth systems I and II,which are used in this *** of 1.5°,2°,and 2.5°are *** all systems,the image qualities are *** the S-ADC relaxes the optical glass size restriction,this 12-m telescope with a FOV of 2.5°can be magnified in proportion to a 16-m *** etendue(from Frenchétendue)and focal surface will now be the largest in the *** such a telescope,a pure reflecting optical system can also be obtained.A subsequent coudésystem is designed with excellent image quality.

关键词： telescopes spectroscopic survey