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Inelastic Scattering of Dark Matter with Heavy Cosmic Rays

Research in astronomy and Astrophysics 2024年第6期24卷 68-80页

作者： Keyu Lu Yue-Lin Sming Tsai Qiang Yuan Le Zhang School of Physics and astronomy Sun Yat-sen UniversityZhuhai 519082China 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 CSST Science Center for the Guangdong-Hong Kong-Macao Greater Bay Area SYSUZhuhai 519082China Peng Cheng Laboratory Shenzhen 518000China

We investigate the impact of inelastic collisions between dark matter(DM)and heavy cosmic ray(CR)nuclei on CR *** approximate the fragmentation cross-sections for DM-CR collisions using collider-measured proton-nuclei scattering cross-sections,allowing us to assess how these collisions affect the spectra of CR boron and *** derive new CR spectra from DM-CR collisions by incorporating their cross-sections into the source terms and solving the diffusion equation for the complete network of reactions involved in generating secondary *** a specific example with a coupling strength of b_(χ)=0.1 and a DM mass of m_(χ)=0.1 GeV,considering a simplified scenario where DM interacts exclusively with oxygen,a notable modification in the boron-to-carbon spectrum due to the DM-CR interaction is ***,the peak within the spectrum,spanning from 0.1 to 10 GeV,experiences an enhancement of approximately 1.5 ***,in a more realistic scenario where DM particles interact with all CRs,this peak can be amplified to twice its original *** the latest data from AMS-02 and DAMPE on the boron-to-carbon ratio,we estimate a 95%upper limit for the effective inelastic cross-section of DM-proton as a function of DM *** findings reveal that at m_(χ)?2 MeV,the effective inelastic cross-section between DM and protons must be less than O(10^(-32))cm^(2).

关键词： elementary particles nuclear reactions nucleosynthesis abundances scattering astroparticle physics (cosmology:)dark matter

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Long-term Evolution of Solar Activity and Prediction of the Following Solar Cycles

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Research in astronomy and Astrophysics 2024年第3期24卷 194-204页

作者： Pei-Xin Luo Bao-Lin Tan National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China School of astronomy and space Science University of Chinese Academy of SciencesBeijing 100049China

Solar activities have a great impact on modern high-tech systems,such as human aerospace activities,satellite communication and navigation,deep space exploration,and related scientific ***,studying the long-term evolution trend of solar activity and accurately predicting the future solar cycles are highly *** on the wavelet transform and empirical function fitting of the longest recorded data of the annual average relative sunspot number(ASN)series of 323 yr to date,this work decisively verifies the existence of the solar century cycles and confirms that its length is about 104.0 yr,and the magnitude has a slightly increasing trend on the timescale of several hundred *** on this long-term evolutionary trend,we predict solar cycles 25 and26 by using phase similar prediction *** for solar cycle 25,its maximum ASN will be about146.7±33.40,obviously stronger than solar cycle *** peak year will occur approximately in 2024,and the period will be about 11±1 *** for solar cycle 26,it will start around 2030,and reach its maximum between2035 and 2036,with maximum ASN of about 133.0±3.200,and period of about 10 yr.

关键词： Sun activity-Sun evolution-(Sun) sunspots-methods data analysis

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First Digit Distributions of Gamma-Ray Bursts

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Research in astronomy and Astrophysics 2024年第5期24卷 70-75页

作者： Hou-Yu Lai Jun-Jie Wei Purple Mountain Observatory Chinese Academy of SciencesNanjing 210023China School of astronomy and space Sciences University of Science and Technology of ChinaHefei 230026China

The occurrence of the first significant digits from real world sources is usually not equally distributed,but is consistent with a logarithmic distribution instead,known as Benford’s *** this work,we perform a comprehensive investigation on the first digit distributions of the duration,fluence,and energy flux of gamma-ray bursts (GRBs) for the first *** a complete GRB sample detected by the Fermi satellite,we find that the first digits of the duration and fluence adhere to Benford’s ***,the energy flux shows a significant departure from this law,which may be due to the fact that a considerable part of the energy flux measurements is restricted by lack of spectral *** on the conventional duration classification scheme,we also check if the durations and fluences of long and short GRBs (with duration T_(90)>2 s and T_(90)≤2 s,respectively) obey Benford’s *** find that the fluences of both long and short GRBs still agree with the Benford distribution,but their durations do not follow Benford’s *** results hint that the long–short GRB classification scheme does not directly represent the intrinsic physical classification scheme.

关键词： (stars:)gamma-ray burst general-methods statistical-astronomical databases miscellaneous

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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

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Kinetic scale magnetic holes in the terrestrial magnetosheath:A review

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Science China Earth Sciences 2024年第9期67卷 2739-2771页

作者： Quanqi SHI Shutao YAO Maria HAMRIN Ji LIU Shandong Provincial Key Laboratory of Optical astronomy and Solar-Terrestrial Environment Institute of Space SciencesShandong UniversityWeihai 264209China department of Physics UmeåUniversityUmeå90746Sweden department of Physics University of AlbertaEdmonton T6K 2P6Canada

Magnetic holes at the ion-to-electron kinetic scale(KSMHs)are one of the extremely small intermittent structures generated in turbulent magnetized *** recent years,the explorations of KSMHs have made substantial strides,driven by the ultra-high-precision observational data gathered from the Magnetospheric Multiscale(MMS)*** review paper summarizes the up-to-date characteristics of the KSMHs observed in Earth’s turbulent magnetosheath,as well as their potential impacts on space *** review starts by introducing the fundamental properties of the KSMHs,including observational features,particle behaviors,scales,geometries,and distributions in terrestrial *** have discovered that KSMHs display a quasi-circular electron vortex-like structure attributed to electron diamagnetic *** electrons exhibit noticeable non-gyrotropy and undergo *** occurrence rate of KSMH in the Earth’s magnetosheath is significantly greater than in the solar wind and magnetotail,suggesting the turbulent magnetosheath is a primary source ***,KSMHs have also been generated in turbulence simulations and successfully reproduced by the kinetic equilibrium ***,KSMHs have demonstrated their ability to accelerate electrons by a novel non-adiabatic electron acceleration mechanism,serve as an additional avenue for energy dissipation during magnetic reconnection,and generate diverse wave phenomena,including whistler waves,electrostatic solitary waves,and electron cyclotron waves in space *** results highlight the magnetic hole’s impact such as wave-particle interaction,energy cascade/dissipation,and particle acceleration/heating in space *** end this paper by summarizing these discoveries,discussing the generation mechanism,similar structures,and observations in the Earth’s magnetotail and solar wind,and presenting a future extension perspective in this active field.

关键词： Magnetic hole Magnetic dip/cavity Electron vortex Magnetosheath Turbulence Coherent structure Mirror mode Kinetic scale Electron acceleration Whistler

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Few-shot incremental radar target recognition framework based on scattering-topology properties

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Chinese Journal of Aeronautics 2024年第8期37卷 246-260页

作者： Chenxuan LI Weigang ZHU Bakun ZHU Yonggang LI Graduate School Space Engineering UniversityBeijing 101400China department of Electronic and Optical Engineering Space Engineering UniversityBeijing 101400China

The continuous emergence of new targets in open scenarios leads to a substantial decrease in the performance of Inverse Synthetic Aperture Radar(ISAR)recognition ***,data scarcity further exacerbates the challenge of identifying new classes of ISAR *** this paper,a few-shot incremental target recognition framework based on Scattering-Topology Properties(STPIL)is ***,STPIL extracts scattering-topology properties of ISAR targets as recognition ***,the pseudo-incremental training strategy effectively alleviates the algorithm’s forgetting of old knowledge,and improves compatibility with new ***,a feature embedding network,with few parameters,is designed based on the graph neural *** embedding network is highly adaptable to changes in data ***,STPIL fully considers the joint distribution and marginal distribution in scattering features,and uses the Brownian distance metric module to make the scattering-topology features more *** results on both the simulation dataset and the public measured data indicate that STPIL can effectively balance new classes with old classes,and has superior performance to other advanced methods in the incremental recognition of targets.

关键词： Brownian distance metric Graph neural networks Incremental learning Inverse Synthetic Aperture Radar(ISAR) Scattering

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Recent advances in the magnetic reconnection, dipolarization, and auroral processes at giant planets from the perspective of comparative planetology

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Earth and Planetary Physics 2024年第5期8卷 659-672页

作者： ZhongHua Yao RuiLong Guo Yong Wei Bertrand Bonfond Denis Grodent BinZheng Zhang William R.Dunn ZuYin Pu Key Laboratory of Earth and Planetary Physics Institute of Geology and GeophysicsChinese Academy of Sciences College of Earth and Planetary Sciences University of Chinese Academy of Sciences Laboratoire de Physique Atmosphérique et Planétaire STAR InstituteUniversitéde Liège Shandong Provincial Key Laboratory of Optical astronomy and Solar-Terrestrial Environment Institute of Space SciencesShandong University department of Earth Sciences the University of Hong Kong department of Physics and astronomy University College London School of Earth and space Sciences Peking University

Magnetic reconnection and dipolarization are crucial processes driving magnetospheric dynamics, including particle energization, mass circulation, and auroral processes, among others. Recent studies have revealed that these processes at Saturn and Jupiter are fundamentally different from the ones at Earth. The reconnection and dipolarization processes are far more important than previously expected in the dayside magnetodisc of Saturn and potentially Jupiter. Dayside magnetodisc reconnection was directly identified by using Cassini measurements(Guo RL et al., 2018b) and was found to be drizzle-like and rotating in the magnetosphere of Saturn(Delamere et al., 2015b; Yao ZH et al., 2017a; Guo RL et al., 2019). Moreover, magnetic dipolarization could also exist at Saturn's dayside(Yao ZH et al., 2018), which is fundamentally different from the terrestrial situation. These new results significantly improve our understanding of giant planetary magnetospheric dynamics and provide key insights revealing the physics of planetary aurorae. Here, we briefly review these recent advances and their potential implications for future investigations.

关键词： magnetosphere magnetic reconnection magnetic depolarization

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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

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Probing turbulence in galaxies with fast radio burst scintillation

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Science China(Physics,Mechanics & astronomy) 2024年第1期67卷 177-178页

作者： James M.Cordes department of astronomy the Cornell Center for Astrophysics and Planetary ScienceCornell UniversityIthaca NY 14853USA

Interstellar scintillation(ISS)is a well-known phenomenon observed from pulsars in the Milky *** comprises intensity variations *** and frequency caused by constructive and destructive interference from multipath propagation,which is due to diffraction from fluctuations in electron density in the interstellar medium(ISM)on scales as small as~100 *** density fluctuations appear to be part of a turbulence process combined with discrete structures in electron density from other astrophysical processes;together these fluctuations extend to scales of pc or larger.

关键词： scales galaxies turbulence

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On the apparent line-of-sight alignment of the peak X-ray intensity of the magnetosheath and the tangent to the magnetopause,as viewed by SMILE-SXI

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Earth and Planetary Physics 2024年第1期8卷 155-172页

作者： Andrew Read department of Physics&astronomy University of LeicesterLeicesterLE17RHUK

The Soft X-ray Imager(SXI)on board the Solar wind Magnetosphere Ionosphere Link Explorer(SMILE)spacecraft will be able to view the Earth’s magnetosheath in soft *** images of the X-ray emission visible from the position of SMILE are created for a range of solar wind densities by using 3 years of the SMILE mission orbit,together with models of the expected X-ray emissivity from the Earth’s *** from global magnetohydrodynamic simulations and a simple model for exospheric neutral densities are used to compare the locations of the lines of sight along which integrated soft X-ray intensities peak with the lines of sight lying tangent to surfaces(defined here to be the magnetopause)along which local soft X-ray intensities peak or exhibit their strongest gradients,or both,for strongly southward interplanetary magnetic field conditions when no depletion or low-latitude boundary layers are ***,in the parameter space of the various times and seasons,orbital phases,solar wind conditions,and magnetopause models,the alignment of the X-ray emission peak with the magnetopause tangent is good,or is not,is *** main results are as *** spacecraft needs to be positioned well outside the magnetopause;low-altitude times near perigee are not *** addition,there are seasonal aspects:dayside-apogee orbits are generally very good because the spacecraft travels out sunward at high altitude,but nightside-apogee orbits,behind the Earth,are bad because the spacecraft only rarely leaves the ***-apogee and dawnapogee orbits are ***-apogee orbits worsen slightly over the first three mission years,whereas nightside-apogee orbits improve ***,many more times of good agreement with the peak-to-tangent hypothesis occur when the solar wind is in a high-density state,as opposed to a low-density *** a high-density state,the magnetopause is compressed,and the spacecraft is more often a good d

关键词： X-rays magnetosphere magnetosheath magnetopause Solar wind Magnetosphere Ionosphere Link Explorer(SMILE) Earth solar wind charge exchange

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