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Beyond the lab:a nanoimprint metalens arraybased augmented reality

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Light(Science & Applications) 2024年第5期13卷 801-802页

作者： Chi Lio Haoran Ren school of Physics and astronomy Monash UniversityMelbourneVICAustralia

A see-through augmented reality prototype has been developed based on an ultrathin nanoimprint metalens array,opening up a full-colour,video-rate,and low-cost 3D near-eye display.

关键词： cost ens imprint

Phonon resonance modulation in weak van der Waals heterostructures:Controlling thermal transport in graphene-silicon nanoparticle systems

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Chinese Physics B 2024年第4期33卷 96-102页

作者：李毅刘一浓胡世谦 school of Physics and astronomy Yunnan UniversityKunming 650091China

The drive for efficient thermal management has intensified with the miniaturization of electronic devices.This study explores the modulation of phonon transport within graphene by introducing silicon nanoparticles influenced by van der Waals forces.Our approach involves the application of non-equilibrium molecular dynamics to assess thermal conductivity while varying the interaction strength,leading to a noteworthy reduction in thermal conductivity.Furthermore,we observe a distinct attenuation in length-dependent behavior within the graphene-nanoparticles system.Our exploration combines wave packet simulations with phonon transmission calculations,aligning with a comprehensive analysis of the phonon transport regime to unveil the underlying physical mechanisms at play.Lastly,we conduct transient molecular dynamics simulations to investigate interfacial thermal conductance between the nanoparticles and the graphene,revealing an enhanced thermal boundary conductance.This research not only contributes to our understanding of phonon transport but also opens a new degree of freedom for utilizing van der Waals nanoparticle-induced resonance,offering promising avenues for the modulation of thermal properties in advanced materials and enhancing their performance in various technological applications.

关键词： thermal conductivity molecular dynamics phonon resonance van der Waals interaction graphene-silicon nanoparticle heterostructure

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 detected.Considering 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)

Surface growth approach for bulk reconstruction in the AdS/BCFT correspondence

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Chinese Physics C 2024年第6期48卷 222-231页

作者：方西浩陈方中孙佳睿 school of Physics and astronomy Sun Yat-Sen UniversityGuangzhou 510275China

In this study,we extend the surface growth approach for bulk reconstruction into the Ad S spacetime with a boundary in the Ad S/BCFT correspondence.We show that the geometry in the entanglement wedge with a boundary can be constructed from the direct growth of bulk extremal surfaces layer by layer.Furthermore,we observe that the surface growth configuration in BCFT can be connected with the defect multi scale entanglement renormalization ansatz(MERA)tensor network.Additionally,we investigate the entanglement of purification within the surface growth process,which not only reveals more refined structure of entanglement entropy in the entanglement wedge but also suggests a selection rule for surface growth in the bulk reconstruction.

关键词： AdS/CFT correspondence gauge/gravity duality models of quantum gravity

Inelastic Scattering of Dark Matter with Heavy Cosmic Rays

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Research in astronomy and Astrophysics 2024年第6期24卷 70-82页

作者： Keyu Lu Yue-Lin Sming Tsai Qiang Yuan Le Zhang school of Physics and astronomy Sun Yat-sen University Key Laboratory of Dark Matter and Space astronomy Purple Mountain Observatory Chinese Academy of Sciences school of astronomy and Space Science University of Science and Technology of China CSST Science Center for the Guangdong-Hong Kong-Macau Greater Bay Area SYSU Peng Cheng Laboratory

We investigate the impact of inelastic collisions between dark matter （DM） and heavy cosmic ray （CR） nuclei on CR propagation.We 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 carbon.We 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 species.In a specific example with a coupling strength of bχ=0.1 and a DM mass of mχ=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 observed.Particularly,the peak within the spectrum,spanning from 0.1 to 10 GeV,experiences an enhancement of approximately 1.5 times.However,in a more realistic scenario where DM particles interact with all CRs,this peak can be amplified to twice its original value.Utilizing 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 mass.Our findings reveal that at mχ?2 MeV,the effective inelastic cross-section between DM and protons must be less than O(10-32) cm2.

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

On the Performances of Estimating Stellar Atmospheric Parameters from CSST Broad-band Photometry

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Research in astronomy and Astrophysics 2024年第4期24卷 161-173页

作者： Rui-Feng Shi Yang Huang Xin-Yi Li Hua-Wei Zhang school of astronomy and Space Science University of Chinese Academy of SciencesBeijing 100049China South-Western Institute for astronomy Research Yunnan UniversityKunming 650500China CAS Key Lab of Optical astronomy Key Laboratory of Space Astronomy and TechnologyNational Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China College of Physics and Electronic Engineering Qilu Normal UniversityJinan 250200China Department of astronomy School of PhysicsPeking UniversityBeijing 100871China Kavli Institute for astronomy and Astrophysics Peking UniversityBeijing 100871China

Deriving atmospheric parameters of a large sample of stars is of vital importance to understand the formation and evolution of the Milky Way.Photometric surveys,especially those with near-ultraviolet filters,can offer accurate measurements of stellar parameters,with the precision comparable to that from low/medium resolution spectroscopy.In this study,we explore the capability of measuring stellar atmospheric parameters from Chinese Space Station Telescope(CSST)broad-band photometry(particularly in the near-ultraviolet bands),based on synthetic colors derived from model spectra.We find that colors from the optical and near-ultraviolet filter systems adopted by CSST show significant sensitivities to the stellar atmospheric parameters,especially the metallicity.According to our mock data tests,the precision of the photometric metallicity is quite high,with typical values of0.17 and 0.20 dex for dwarf and giant stars,respectively.The precision of the effective temperature estimated from broad-band colors are within 50 K.

关键词： methods:data analysis stars:abundances surveys

Low Surface Brightness Galaxies Selected by Different Model Fitting

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Research in astronomy and Astrophysics 2024年第1期24卷 223-236页

作者： Bing-Qing Zhang Hong Wu Wei Du Pin-Song Zhao Min He Feng-Jie Lei Key Laboratory of Optical astronomy National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China school of astronomy and Space Science University of Chinese Academy of SciencesBeijing 100049China

We present a study of low surface brightness galaxies(LSBGs) selected by fitting the images for all the galaxies inα.40 SDSS DR7 sample with two kinds of single-component models and two kinds of two-component models(disk+bulge):single exponential,single sersic,exponential+deVaucular(exp+deV),and exponential+sérsic(exp+ser).Under the criteria of the B band disk central surface brightness μ_(0,disk)(B)≥22.5 mag arcsec^(-2) and the axis ratio b/a> 0.3,we selected four none-edge-on LSBG samples from each of the models which contain 1105,1038,207,and 75 galaxies,respectively.There are 756 galaxies in common between LSBGs selected by exponential and sersic models,corresponding to 68.42% of LSBGs selected by the exponential model and 72.83% of LSBGs selected by the sersic model,the rest of the discrepancy is due to the difference in obtaining μ_(0) between the exponential and sersic models.Based on the fitting,in the range of 0.5≤n≤1.5,the relation of μ_(0) from two models can be written as μ_(0,sérsic)-μ_(0,exp)=-1.34(n-1).The LSBGs selected by disk+bulge models(LSBG_(2)comps) are more massive than LSBGs selected by single-component models(LSBG_1comp),and also show a larger disk component.Though the bulges in the majority of our LSBG_(2)comps are not prominent,more than 60% of our LSBG_(2)comps will not be selected if we adopt a single-component model only.We also identified 31 giant low surface brightness galaxies(gLSBGs) from LSBG_(2)comps.They are located at the same region in the color-magnitude diagram as other gLSBGs.After we compared different criteria of gLSBGs selection,we find that for gas-rich LSBGs,M_(*)> 10^(10)M_⊙ is the best to distinguish between gLSBGs and normal LSBGs with bulge.

关键词： catalogs galaxies:spiral galaxies:bulges methods:data analysis methods:statistical

Black holes as the source of dark energy:A stringent test with high-redshift JWST AGNs

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Science China(Physics,Mechanics & astronomy) 2024年第2期67卷 181-188页

作者： Lei Lei Lei Zu Guan-Wen Yuan Zhao-Qiang Shen Yi-Ying Wang Yuan-Zhu Wang Zhen-Bo Su Wen-Ke Ren Shao-Peng Tang Hao Zhou Chi Zhang Zhi-Ping Jin Lei Feng Yi-Zhong Fan Da-Ming Wei 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 CAS Key Laboratory for Research in Galaxies and Cosmology Department of AstronomyUniversity of Science and Technology of ChinaHefei 230026China

Studies have proposed that there is evidence for cosmological coupling of black holes(BHs)with an index of k≈3;hence,BHs serve as the astrophysical source of dark energy.However,the data sample is limited for the redshifts of≤2.5.In recent years,the James Webb Space Telescope(JWST)has detected many high-redshift active galactic nuclei(AGNs)and quasars.Among the JWST NIRSpec-/NIRCam-resolved AGNs,three are determined to be in early-type host galaxies with a redshift of z~4.5-7.However,their M_(*)and MBH are in tension with the predicted cosmological coupling of black holes with k=3 at a confidence level of~2σ,which challenges the hypothesis that BHs serve as the origin of dark energy.Future work on high-redshift AGNs using the JWST will further assess such a hypothesis by identifying more early-type host galaxies in the higher mass range.

关键词： dark energy supermassive black hole active galactic nuclei James Webb Space Telescope

The Multi-parameter Test of Gravitational Wave Dispersion with Principal Component Analysis

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Research in astronomy and Astrophysics 2024年第5期24卷 140-150页

作者： Zhi-Chu Ma Rui Niu Wen Zhao CAS Key Laboratory for Research in Galaxies and Cosmology Department of AstronomyUniversity of Science and Technology of ChinaHefei 230026China school of astronomy and Space Sciences University of Science and Technology of ChinaHefei 230026China

In this work, we consider a conventional test of gravitational wave(GW) propagation which is based on the phenomenological parameterized dispersion relation to describe potential departures from General Relativity(GR)along the propagation of GWs. But different from tests conventionally performed previously, we vary multiple deformation coefficients simultaneously and employ the principal component analysis(PCA) method to remedy the strong degeneracy among deformation coefficients and obtain informative posteriors. The dominant PCA components can be better measured and constrained, and thus are expected to be more sensitive to potential departures from the waveform model. Using this method we analyze ten selected events and get the result that the combined posteriors of the dominant PCA parameters are consistent with GR within 99.7% credible intervals. The standard deviation of the first dominant PCA parameter is three times smaller than that of the original dispersion parameter of the leading order. However, the multi-parameter test with PCA is more sensitive to not only potential deviations from GR but also systematic errors of waveform models. The difference in results obtained by using different waveform templates hints that the demands of waveform accuracy are higher to perform the multiparameter test with PCA. Whereas, it cannot be strictly proven that the deviation is indeed and only induced by systematic errors. It requires more thorough research in the future to exclude other possible reasons in parameter estimation and data processing.

关键词： gravitational waves-gravitation-black hole physics