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National Science Review 2024年第2期11卷 65-80页

作者： Chaowei Hu Tiema Qian Ni Ni department of physics and astronomy and California Nano Systems institute University of California-Los Angeles

The search for magnetic topological materials has been at the forefront of condensed matter research for their potential to host exotic states such as axion insulators, magnetic Weyl semimetals, Chern insulators,etc. To date, the MnBi2nTe3n+1family is the only group of materials showcasing van der Waals-layered structures, intrinsic magnetism and non-trivial band topology without trivial bands at the Fermi level. The interplay between magnetism and band topology in this family has led to the proposal of various topological phenomena, including the quantum anomalous Hall effect, quantum spin Hall effect and quantum magnetoelectric effect. Among these, the quantum anomalous Hall effect has been experimentally observed at record-high temperatures, highlighting the unprecedented potential of this family of materials in fundamental science and technological innovation. In this paper, we provide a comprehensive review of the research progress in this intrinsic magnetic topological insulator family, with a focus on single-crystal growth, characterization of chemical disorder, manipulation of magnetism through chemical substitution and external pressure, and important questions that remain to be conclusively answered.

关键词： MnBi2Te4 magnetic topological insulator magnetism tuning antiferromagnetism ferromagnetism pressure chemical doping

Recent Developments on the H_(I)Gas of Low-Redshift Galaxies Seen by the 21 cm Emission Lines

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Chinese physics Letters 2024年第10期41卷 152-165页

作者： Jing Wang Xuchen Lin Kavli institute for astronomy and Astrophysics Peking UniversityBeijing 100871China department of astronomy School of PhysicsPeking UniversityBeijing 100871China

As a major interstellar medium,the atomic neutral hydrogen(H I)plays an important role in the galaxy *** provides the ingredient for star formation,and sensitively traces the internal processes and external perturbations influencing the *** the beginning of many new radio telescopes and surveys,H_(I)may make a more significant contribution to the understanding of galaxies in the near *** review discusses the major development of the 21 cm emission-line H_(I)observations and studies in the past few years,including its scaling relations with other galaxy properties,its kinematics and structures,its role in environmental studies,and its constraints on hydrodynamical *** local-Universe H_(I)scaling relations of stellar-massselected samples extend smoothly to 10_(9)M⊙stellar mass,with a tentative evolution to the redshift of∼*** development of measurement techniques enables better estimations of H_(I)non-circular motion,dispersion,and thickness,and new observations revealed extended or extra-planar H_(I)structures,both helpfully constraining the gas accretion,stellar feedback,and star formation processes of galaxy evolution models.H_(I)is very useful for tracing the satellite evolution in dense environments,the studies of which would benefit from ongoing blind H_(I)*** simulations still cannot fully reproduce H_(I)gas properties,they help to understand the role of possible factors in regulating H_(I)properties.

关键词： evolution. galaxy stellar

Scalar dark energy models and scalar–tensor gravity:theoretical explanations for the accelerated expansion of the present Universe

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Communications in Theoretical physics 2024年第10期76卷 160-189页

作者： Peixiang Ji Lijing Shao department of astronomy School of Physics Peking University Kavli institute for astronomy and Astrophysics Peking University National Astronomical Observatories Chinese Academy of Sciences

The reason for the present accelerated expansion of the Universe stands as one of the most profound questions in the realm of science, with deep connections to both cosmology and fundamental physics. From a cosmological point of view, physical models aimed at elucidating the observed expansion can be categorized into two major classes: dark energy and modified gravity. We review various major approaches that employ a single scalar field to account for the accelerating phase of our present Universe. Dynamic system analysis was employed in several important models to find cosmological solutions that exhibit an accelerating phase as an *** scalar field models of dark energy, we consistently focused on addressing challenges related to the fine-tuning and coincidence problems in cosmology, as well as exploring potential solutions to them. For scalar–tensor theories and their generalizations, we emphasize the importance of constraints on theoretical parameters to ensure overall consistency with experimental tests. Models or theories that could potentially explain the Hubble tension are also emphasized throughout this review.

关键词： cosmology dark energy dynamic system modified gravity quintessence

(DarkAI)Mapping the large-scale density field of dark matter using artificial intelligence

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Science China(physics,Mechanics & astronomy) 2024年第1期67卷 143-159页

作者： Zitong Wang Feng Shi Xiaohu Yang Qingyang Li Yanming Liu Xiaoping Li School of Aerospace Science and Technology Xidian UniversityXi’an 710126China department of astronomy School of Physics and Astronomyand Shanghai Key Laboratory for Particle Physics and CosmologyShanghai Jiao Tong UniversityShanghai 200240China Tsung-Dao Lee institute and Key Laboratory for Particle physics Astrophysics and CosmologyMinistry of EducationShanghai Jiao Tong UniversityShanghai 200240China institute for astronomy University of EdinburghRoyal ObservatoryEdinburgh EH93HJUnited Kingdom

Herein,we present a deep-learning technique for reconstructing the dark-matter density field from the redshift-space distribution of dark-matter *** built a UNet-architecture neural network and trained it using the COmoving Lagrangian Acceleration fast simulation,which is an approximation of the N-body simulation with 5123 particles in a box size of 500 h^(-1)***,we tested the resulting UNet model not only with training-like test samples but also with standard N-body simulations,such as the Jiutian simulation with 61443particles in a box size of 1000 h^(-1)Mpc and the ELUCID simulation,which has a different *** real-space dark-matter density fields in the three simulations can be reconstructed reliably with only a small reduction of the cross-correlation power spectrum at 1%and 10%levels at k=0.1 and 0.3 h Mpc-1,*** reconstruction clearly helps to correct for redshift-space distortions and is unaffected by the different cosmologies between the training(Planck2018)and test samples(WMAP5).Furthermore,we tested the application of the UNet-reconstructed density field to obtain the velocity&tidal field and found that this approach provides better results compared with the traditional approach based on the linear bias model,showing a 12.2%improvement in the correlation slope and a 21.1%reduction in the scatter between the predicted and true ***,our method is highly efficient and has excellent extrapolation reliability beyond the training *** provides an ideal solution for determining the three-dimensional underlying density field from the plentiful galaxy survey data.

关键词： dark matter large-scale structure cosmology

Design and fabrication of Nd-Fe-B magnet with excellent thermal stability

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Journal of Rare Earths 2024年第5期42卷 980-986,I0006页

作者： Rui Han Shengzhi Dong Dong Li Dongmin Zhang Hongsheng Chen Jiyuan Xu George CHadjipanayis Zhuolin Li Ying Zhang Wei Li Division of Functional Materials Research Central Iron and Steel Research InstituteBeijing100081China department of physics and astronomy Sharp Lab University of DelawareNewarkDE19716USA Beijing National Laboratory for Condensed Matter physics Institute of PhysicsChinese Academy of SciencesBeijing100190China

A novel Nd-Fe-B type permanent magnet with excellent thermal stability was designed by Co replacing Fe in the main phase and the grain boundary *** remanence and coercivity temperature coefficient reach 0.058%/℃and 0.465%/℃in the te mperature range from 25 to 100℃,which are much lower than those of commercial Nd-Fe-B *** enhanced Curie temperature is obtained for the novel magnet due to the Co substitution,which significantly improves the operating *** microstructure result reveals that an amorphous phase exists in the intergranular grains which is probably responsible for the deterioration of intrinsic *** work can provide a reference for the design and optimization of components of sintered Nd-Fe-B magnets with excellent thermal stability.

关键词： Thermal stability Remanence temperature coefficient Operating temperature Atomic substitution Rare earths

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 *** templates are the basis for such matched filtering *** construct ready-to-use waveform templates,numerical relativity waveforms are a starting ***,the accuracy issue of numerical relativity waveforms is critically *** are many investigations regarding this issue with respect to *** unfortunately there are few results on this issue with respect to space-based *** current paper investigates this *** results indicate that the existing numerical relativity waveforms are as accurate as 99%with respect to space-based detectors,including LISA,Taiji and *** an accuracy level is comparable to that with respect to LIGO.

关键词： numerical relativity gravitational wave binary black hole

Weak Merging Scenario of CLASH Cluster A209

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Research in astronomy and Astrophysics 2024年第4期24卷 174-182页

作者： Wen-Cheng Feng Heng Yu Hai-Hui Zhao Xiao-Lan Hou Shu-Mei Jia Cheng-Kui Li Yu-Lin Cheng Paolo Tozzi Ming Sun Yong Chen department of physics and institute of Theoretical physics Nanjing Normal UniversityNanjing 210023China Key Laboratory of Particle Astrophysics Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China department of astronomy Beijing Normal UniversityBeijing 100875China department of astronomy Yunnan UniversityKunming 650091China INAF—Osservatorio Astrofisico di Arcetri Largo E.Fermi50122 FirenzeItaly department of astronomy University of VirginiaP.O.Box 400325CharlottesvilleVA 22904-4325USA

We study the structural and dynamical properties of A209 based on Chandra and XMM-Newton *** obtain detailed temperature,pressure,and entropy maps with the contour binning method,and find a hot region in the NW *** X-ray brightness residual map and corresponding temperature profiles reveal a possible shock front in the NW direction and a cold front feature in the SE *** with the galaxy luminosity density map we propose a weak merger scenario.A young sub-cluster passing from the SE to NW direction could explain the optical subpeak,the intracluster medium temperature map,the X-ray surface brightness excess,and the X-ray peak offset together.

关键词： X rays:galaxies:clusters galaxies:clusters:intracluster medium galaxies:clusters:Abell 209

Observation of Complex Organic Molecules Containing Peptide-like Bonds Toward Hot Core G358.93-0.03 MM1

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Research in astronomy and Astrophysics 2024年第7期24卷 181-189页

作者： Arijit Manna Sabyasachi Pal department of physics and astronomy Midnapore City CollegePaschim MedinipurWest Bengal721129India

In star formation regions,the complex organic molecules(COMs)that contain peptide bonds(-NH-C(=O)-)play a major role in the metabolic process because-NH-C(=O)-is connected to amino acids(R-CHNH_2-COOH).Over the past few decades,many COMs containing peptide-like bonds have been detected in hot molecular cores(HMCs),hot corinos,and cold molecular clouds,however,their prebiotic chemistry is poorly *** present the first detection of the rotational emission lines of formamide(NH_2CHO)and isocyanic acid(HNCO),which contain peptide-like bonds toward the chemically rich HMC G358.93-0.03 MM1,using high-resolution and high-sensitivity Atacama Large Millimeter/submillimeter Array bands 6 and *** estimate that the column densities of NH_2CHO and HNCO toward G358.93-0.03 MM1 are(2.80±0.29)×10~(15)cm~(-2)and(1.80±0.42)×10~(16)cm~(-2)with excitation temperatures of 165±21 K and 170±32 K,*** fractional abundances of NH_2CHO and HNCO toward G358.93-0.03 MM1 are(9.03±1.44)×10~(-10)and(5.80±2.09)×10^(-9).We compare the estimated abundances of NH_2CHO and HNCO with the existing threephase warm-up chemical model abundance values and notice that the observed and modeled abundances are very *** conclude that NH_2CHO is produced by the reaction of NH_2and H_2CO in the gas phase toward G358.93-0.03 ***,HNCO is produced on the surface of grains by the reaction of NH and CO toward G358.93-0.03 *** also find that NH_2CHO and HNCO are chemically linked toward G358.93-0.03 MM1.

关键词： ISM individual objects(G358.93-0.03)-ISM abundances-ISM kinematics and dynamics-stars formation-astrochemistry

Quasinormal modes and ringdown waveforms of a Frolov black hole

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Communications in Theoretical physics 2024年第10期76卷 101-107页

作者： Zhijun Song Huajie Gong Hai-Li Li Guoyang Fu Li-Gang Zhu Jian-Pin Wu Center for Gravitation and Cosmology College of Physical Science and Technology Yangzhou University Basic Teaching department Shenyang Institute of Engineering department of physics and astronomy Shanghai Jiao Tong University

In this paper we investigate scalar perturbation over a Frolov black hole（BH）, which is a regular BH induced by the quantum gravity effect. The quasinormal frequencies of a scalar field always consistently reside in the lower half-plane, and the time-domain evolution of the field demonstrates a decaying behavior, with the late-time tail exhibiting a power-law pattern. These observations collectively suggest the stability of a Frolov BH against scalar ***, our study reveals that the quantum gravity effect leads to slower decay modes. For the case of the angular quantum number l = 0, the oscillation exhibits non-monotonic behavior with the quantum gravity parameter α0. However, once l ≥ 1, the angular quantum number surpasses the influence of the quantum gravity effect.

关键词： black hole Frolov black hole quantum gravity effects quasinormal modes

Revealing high-dimensional dynamical symmetry in alignment magnetic resonance

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Science China(physics,Mechanics & astronomy) 2024年第10期67卷 162-163页

作者： M.Suhail Zubairy institute for Quantum Science and Engineering(IQSE)and department of physics and astronomy Texas A&M UniversityCollege StationTexas 77843-4242USA

Symmetry permeates throughout science,underlying people's understanding on intriguing physical *** include conserved quantities,critical phenomena and selection *** symmetry,the counterpart of geometrical symmetry or static symmetry referring to the geometrical shape or structure of a physical system,is present in the motion behavior.

关键词： properties symmetry alignment