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A Possible γ-Ray Pulsation from PSR J1740-5340B in the Globular Cluster NGC 6397

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Research in astronomy and Astrophysics 2024年第1期24卷 285-291页

作者： Jiao Zheng Pengfei Zhang Li Zhang department of astronomy School of Physics and AstronomyKey Laboratory of Astroparticle Physics of Yunnan ProvinceYunnan UniversityKunming 650091China

Recently, a new radio millisecond pulsar(MSP) J1740-5340B, hosted in the globular cluster(GC) NGC 6397,was reported with a 5.78 ms spin period in an eclipsing binary system with a 1.97 days orbital period. Based on a modified radio ephemeris updated by tool tempo2, we analyze the ~15 yr γ-ray data obtained from the Large Area Telescope on board the Fermi Gamma-ray Space Telescope and detect PSR J1740-5340B's γ-ray pulsation at a confidence level of ~4σ with a weighted H-test value of ~26. By performing a phase-resolved analysis, the γ-ray luminosity in on-pulse interval of PSR J1740-5340B is L_(γ)~ 3.8 × 10^(33) erg s^(-1) using NGC 6397's distance of 2.48 kpc. And γ-rays from the on-pulse part of PSR J1740-5340B contribute ~90% of the total observed γ-ray emissions from NGC 6397. No significant γ-ray pulsation of another MSP J1740-5340A in the GC is *** that the previous four cases of MSPs in GCs, more data in γ-ray, X-ray, and radio are encouraged to finally confirm the γ-ray emissions from MSP J1740-5340B, especially starving for a precise ephemeris.

关键词： gamma-rays:galaxies (stars:)pulsars:individual(PSR J1740-5340B) (Galaxy:)globular clusters:individual(NGC 6397)

Tuning structural,electrical,dielectric and magnetic properties of Mg-Cu-Co ferrites via dysprosium(Dy^(3+))doping

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Journal of Rare Earths 2024年第1期42卷 137-146,I0005页

作者： Maria Akhtar M.S.Hasan Nasir Amin N.A.Morley Muhammad Imran Arshad department of physics Government College UniversityFaisalabad38000Pakistan department of physics The University of Lahore53700Pakistan department of Materials Science and engineering The University of SheffieldS13JDUK department of physics&astronomy University College LondonUK

In current research work,Dy3+substituted Mg0.5Cu0.25Co0.25Fe2-xDyxO4(0.0≤x≤0.04 with the step interval of 0.01)soft ferrites were synthesized by the sol-gel auto combustion *** prepared samples were characterized by the techniques using X-ray diffraction(XRD),scanning electron microscopy(SEM),energy dispersive X-ray spectroscopy(EDS),Fourier transform infrared(FTIR)spectroscopy,curre nt-voltage(Ⅰ-Ⅴ)measurement,LCR meter,vibrating sample magnetometer(VSM)and *** data reveal that the average crystallite size is 49.71 nm and the lattice constant is 0.83703 nm for sample x=*** non-uniform grain growth was demonstrated by micrographs and impurity-free elemental composition was observed from EDX *** DC resistivity has an increasing and decreasing trend in ferromagnetic and paramagnetic regions with an increase in ***,the high resistivity is observed with the order of 1010Ω·cm,and the activation energy is 0.944 eV for samples x=*** dielectric parameters including dielectric constant,dielectric losses,and impedance gradually decrease with the increase in frequency from 8 Hz to 8 *** minimum dielectric loss at high frequency is found for sample x=*** coercivity(Hc)and saturation magnetization(Ms)are found in the ranges of 520.82-544.02 Oe and 20.5841-21.1473 emu/g,*** observations confirm that dysprosium(x=0.03)doped MCC-soft ferrites may be applicable in transformer cores,microwave absorbance,and telecommunication devices.

关键词： Soft ferrites DC resistivity Dielectric loss Impedance Coercivity Rare earths

First evidence for chiral wobbling of triaxial nuclei

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Nuclear Science and Techniques 2024年第7期35卷 4-7页

作者： S.Frauendorf department of physics and astronomy University of Notre DameNotre DameIN 46556USA

Chirality(Greek“handiness”)is a property of many com-plex *** molecules exist in two forms,one being the mirror image of the *** for our hands,it is impossible to make the images identical by a suitable *** two forms are called left-handed and *** have the same binding energy,because the electro-magnetic interaction,which holds the molecule together,does not change under a *** properties that are insensitive to the geometry are also the *** different geometry is the reason why the left-handed form turns the polarization plane of transmitted light in one direction by some angle while the right-handed form turns it in the oppo-site direction by the same ***,the geometrical differences between the two species may have other *** two species of the carvon molecule shown in Fig.1 taste quite differently.

关键词： turns Chiral mirror

Recent progress in MnBi2nTe3n+1 intrinsic magnetic topological insulators: crystal growth, magnetism and chemical disorder

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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

Pulsar Glitch Activities:The Spin Parameters Approach

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Research in astronomy and Astrophysics 2024年第6期24卷 334-357页

作者： Innocent Okwudili Eya Evaristus Uzochukwu Iyida physics/Electronics Technique—department of Science Laboratory Technology University of NigeriaNsukkaNigeria department of physics and astronomy University of NigeriaNsukkaNigeria astronomy and Astrophysics Research Lab University of NigeriaNsukkaNigeria

Glitch activity refers to the mean increase in pulsar spin frequency per year due to rotational *** is an important tool for studying super-nuclear matter using neutron star interiors as *** events are typically observed in the spin frequency(ν) and frequency derivative( ν) of *** rate of glitch recurrence decreases as the pulsar ages,and the activity parameter is usually measured by linear regression of cumulative glitches over a given *** method is effective for pulsars with multiple regular glitch ***,due to the scarcity of glitch events and the difficulty of monitoring all known pulsars,only a few have multiple records of glitch *** limits the use of the activity parameter in studying neutron star interiors with multiple *** this study,we examined the relationship between the activity parameters and pulsar spin parameters(spin frequency,frequency derivative,and pulsar characteristic age).We found that a quadratic function provides a better fit for the relationship between activity parameters and spin parameters than the commonly used linear *** this information,we were able to estimate the activity parameters of other pulsars that do not have records of *** analysis shows that the relationship between the estimated activity parameters and pulsar spin parameters is consistent with that of the observed activity parameters in the ensemble of pulsars.

关键词： stars:neutron (stars:)pulsars:general methods:statistical

New γ-Ray Sources Identified in All-sky Surveys Based on Fermipy's Advanced Algorithm

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Research in astronomy and Astrophysics 2024年第10期24卷 81-91页

作者： Yunchuan Xiang Peng Feng Xiaofei Lan School of physics and astronomy China West Normal UniversityNanchong 637009China department of astronomy Yunnan Universityand Key Laboratory of Astroparticle Physics of Yunnan ProvinceKunming 650091China

We employ an efficient method for identifying γ-ray sources across the entire sky,leveraging advanced algorithms from Fermipy,and cleverly utilizing the Galactic diffuse background emission model to partition the entire sky into72 regions,thereby greatly enhancing the efficiency of discovering new sources throughout the sky through multithreaded parallel *** confirming the reliability of the new method,we applied it for the first time to analyze data from the Fermi Large Area Telescope(Fermi-LAT)encompassing approximately 15.41 yr of all-sky *** this analysis,we successfully identified 1379 new sources with significance levels exceeding 4σ,of which 497 sources exhibited higher significance levels exceeding 5σ.Subsequently,we performed a systematic analysis of the spatial extension,spectra,and light variation characteristics of these newly identified *** identified 21 extended sources and 23 sources exhibiting spectral curvature above 10 ***,we identified 44 variable sources above 1 GeV.

关键词： gamma-rays:diffuse background methods:data analysis catalogs gamma-rays:general

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

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

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