In this paper we consider a static spherically symmetric black hole(BH)embedded in a Dehnen-(1,4,0)-type dark matter(DM)halo in the presence of a cloud string.We examine and present data on how the core density of the...In this paper we consider a static spherically symmetric black hole(BH)embedded in a Dehnen-(1,4,0)-type dark matter(DM)halo in the presence of a cloud string.We examine and present data on how the core density of the DM halo parameter and the cloud string parameter affect BH attributes such as quasinormal modes(QNMs)and shadow cast.To do this,we first look into the effective potential of perturbation equations for three types of perturbation fields with different spins:massless scalar field,electromagnetic field and gravitational field.Then,using the sixth-order Wentzel-Kramers-Brillouin approximation,we examine QNMs of the BH disturbed by the three fields and derive quasinormal frequencies.The changes in QNM versus the core density parameter and the cloud string parameter for three disturbances are explored.We also investigate how the core density and the cloud string parameter affect the photon sphere and shadow radius.Interestingly,the study shows that the influence of Dehnen-type DM and cloud strings increases both the photon sphere and the shadow radius.Finally,we employ observational data from Sgr A^(*) and M87^(*) to set limitations on the BH parameters.展开更多
With the significant development of high-intensity hadron(proton and heavy ion)accelerator facilities,the space charge effect has become a major limiting factor for increasing beam intensity because it can drive parti...With the significant development of high-intensity hadron(proton and heavy ion)accelerator facilities,the space charge effect has become a major limiting factor for increasing beam intensity because it can drive particle resonance,forming beam halos and causing beam quality degradation or even beam loss.In studies on space charge,the particle-core model(PCM)has been widely adopted to describe halo particle formation.In this paper,we generalize the conventional PCM to include dispersion to investigate the physical mechanism of the beam halo in high-intensity synchrotrons.In particular,a“1:1 parametric resonance”driven by the combined effects of space charge and dispersion is identified.A large dispersion is proven to have a damping effect on the 2:1 parametric resonance.The analysis based on the generalized PCM agrees with particle-in-cell simulations.A beam halo with large mismatch oscillations is also discussed.展开更多
Using a semi-analytic approach,we estimate halo spins for a large sample of H I-rich galaxies from the Arecibo Legacy Fast ALFA Survey and examine the correlation between H I mass fractions and halo spins.Our analysis...Using a semi-analytic approach,we estimate halo spins for a large sample of H I-rich galaxies from the Arecibo Legacy Fast ALFA Survey and examine the correlation between H I mass fractions and halo spins.Our analysis reveals a strong correlation between halo spin and the H I-to-stellar mass ratio in both low-mass and massive galaxy samples.This finding suggests a universal formation scenario:higher halo spin reduces angular momentum loss and gas condensation,leading to lower star formation rates and weaker feedback,which in turn help retain gas within dark matter halos.展开更多
Leveraging the semi-analytic method,we compute halo spins for a substantial sample of H I-bearing galaxies observed in the Arecibo Legacy Fast ALFA Survey.Our statistical analysis reveals a correlation between halo sp...Leveraging the semi-analytic method,we compute halo spins for a substantial sample of H I-bearing galaxies observed in the Arecibo Legacy Fast ALFA Survey.Our statistical analysis reveals a correlation between halo spin and environment,although the trend is subtle.On average,galaxies exhibit a decreasing halo spin tendency in denser environments.This observation contrasts with previous results from N-body simulations in the Lambda Cold Dark Matter framework.The discrepancy may be attributed to environmental gas stripping,leading to an underestimation of halo spins in galaxies in denser environments,or to baryonic processes that significantly alter the original dark matter halo spins,deviating from previous N-body simulation findings.展开更多
This study examines the properties of standard cold dark matter(CDM),fuzzy dark matter(FDM),and selfinteracting dark matter(SIDM)haloes by analyzing the rotation curves of selected dwarf galaxies from SPARC and LITTLE...This study examines the properties of standard cold dark matter(CDM),fuzzy dark matter(FDM),and selfinteracting dark matter(SIDM)haloes by analyzing the rotation curves of selected dwarf galaxies from SPARC and LITTLE THINGS in 3D catalogs.Utilizing the Markov Chain Monte Carlo(MCMC)method for model fitting and Bayesian Information Criterion for model comparison,we find that compared to CDM,both FDM and SIDM haloes generally provide better fits to the observed rotation curves.Our findings reveal that the concentration–mass relation derived from the dark matter-only simulations is not followed by concentrations or masses obtained from the rotation curve data.Our analysis highlights a positive correlation between the core sizes of FDM and SIDM haloes and the effective radius of the galaxy,attributable to gravitational couplings between baryonic and dark matter components.Moreover,our exploration of dark matter fractions at characteristic radii indicates considerable diversity in dark matter distributions across dwarf galaxies.Notably,FDM and SIDM exhibit greater diversity than CDM in this respect.展开更多
In this paper,we study the rotation curves of the Milky Way galaxy and Andromeda galaxy(M31)by considering their bulge,disk,and halo components.We model the bulge region by the widely accepted de Vaucouleur’s law and...In this paper,we study the rotation curves of the Milky Way galaxy and Andromeda galaxy(M31)by considering their bulge,disk,and halo components.We model the bulge region by the widely accepted de Vaucouleur’s law and the disk region by the well established exponential profile.In order to understand the distribution of dark matter in the halo region,we consider three different dark matter profiles in the framework of the standardΛCDM model namely,Navarro-Frenk-White(NFW),Hernquist and Einasto profiles.We use recent data sets of rotation curves of the Milky Way and Andromeda galaxy.The data consist of rotation velocities of the stars and gas in the galaxy as a function of the radial distance from the center.Using Bayesian statistics,we perform an overall fit including all the components,i.e.,bulge,disk and halo with the data.Our results indicate that the NFW and Hernquist profiles are in concordance with the observational data points.However,the Einasto profile poorly explains the behavior of dark matter in both the galaxies.展开更多
基金supported by the National Natural Science Foundation of China under Grant No.11675143the National Key Research and Development Program of China under Grant No.2020YFC2201503。
文摘In this paper we consider a static spherically symmetric black hole(BH)embedded in a Dehnen-(1,4,0)-type dark matter(DM)halo in the presence of a cloud string.We examine and present data on how the core density of the DM halo parameter and the cloud string parameter affect BH attributes such as quasinormal modes(QNMs)and shadow cast.To do this,we first look into the effective potential of perturbation equations for three types of perturbation fields with different spins:massless scalar field,electromagnetic field and gravitational field.Then,using the sixth-order Wentzel-Kramers-Brillouin approximation,we examine QNMs of the BH disturbed by the three fields and derive quasinormal frequencies.The changes in QNM versus the core density parameter and the cloud string parameter for three disturbances are explored.We also investigate how the core density and the cloud string parameter affect the photon sphere and shadow radius.Interestingly,the study shows that the influence of Dehnen-type DM and cloud strings increases both the photon sphere and the shadow radius.Finally,we employ observational data from Sgr A^(*) and M87^(*) to set limitations on the BH parameters.
基金supported by the National Natural Science Foundation of China(No.12475155)the GuangDong Basic and Applied Basic Research Foundation(No.2024A1515012658)the International Partnership Program of Chinese Academy of Sciences(No.013GJHZ2023026FN)。
文摘With the significant development of high-intensity hadron(proton and heavy ion)accelerator facilities,the space charge effect has become a major limiting factor for increasing beam intensity because it can drive particle resonance,forming beam halos and causing beam quality degradation or even beam loss.In studies on space charge,the particle-core model(PCM)has been widely adopted to describe halo particle formation.In this paper,we generalize the conventional PCM to include dispersion to investigate the physical mechanism of the beam halo in high-intensity synchrotrons.In particular,a“1:1 parametric resonance”driven by the combined effects of space charge and dispersion is identified.A large dispersion is proven to have a damping effect on the 2:1 parametric resonance.The analysis based on the generalized PCM agrees with particle-in-cell simulations.A beam halo with large mismatch oscillations is also discussed.
基金support from the National Natural Science Foundation of China(NSFC)grant 12273037the CAS Pioneer Hundred Talents Program(Category B)+1 种基金the USTC Research Funds of the Double First-Class Initiativesupported by the China Manned Space Program with grant No.CMS-CSST-2025-A06 and CMS-CSST-2025-A08.
文摘Using a semi-analytic approach,we estimate halo spins for a large sample of H I-rich galaxies from the Arecibo Legacy Fast ALFA Survey and examine the correlation between H I mass fractions and halo spins.Our analysis reveals a strong correlation between halo spin and the H I-to-stellar mass ratio in both low-mass and massive galaxy samples.This finding suggests a universal formation scenario:higher halo spin reduces angular momentum loss and gas condensation,leading to lower star formation rates and weaker feedback,which in turn help retain gas within dark matter halos.
基金supports from the CAS Pioneer Hundred Talents Program(Category B)the National Natural Science Foundation of China(NSFC,grant No.12273037)the USTC Research Funds of the Double First-Class Initiative。
文摘Leveraging the semi-analytic method,we compute halo spins for a substantial sample of H I-bearing galaxies observed in the Arecibo Legacy Fast ALFA Survey.Our statistical analysis reveals a correlation between halo spin and environment,although the trend is subtle.On average,galaxies exhibit a decreasing halo spin tendency in denser environments.This observation contrasts with previous results from N-body simulations in the Lambda Cold Dark Matter framework.The discrepancy may be attributed to environmental gas stripping,leading to an underestimation of halo spins in galaxies in denser environments,or to baryonic processes that significantly alter the original dark matter halo spins,deviating from previous N-body simulation findings.
基金financially supporting this research through PPMI KK 2024 Program,contract number 616BO/IT1.C02/KU/2024。
文摘This study examines the properties of standard cold dark matter(CDM),fuzzy dark matter(FDM),and selfinteracting dark matter(SIDM)haloes by analyzing the rotation curves of selected dwarf galaxies from SPARC and LITTLE THINGS in 3D catalogs.Utilizing the Markov Chain Monte Carlo(MCMC)method for model fitting and Bayesian Information Criterion for model comparison,we find that compared to CDM,both FDM and SIDM haloes generally provide better fits to the observed rotation curves.Our findings reveal that the concentration–mass relation derived from the dark matter-only simulations is not followed by concentrations or masses obtained from the rotation curve data.Our analysis highlights a positive correlation between the core sizes of FDM and SIDM haloes and the effective radius of the galaxy,attributable to gravitational couplings between baryonic and dark matter components.Moreover,our exploration of dark matter fractions at characteristic radii indicates considerable diversity in dark matter distributions across dwarf galaxies.Notably,FDM and SIDM exhibit greater diversity than CDM in this respect.
基金supported by the Startup Research Fund of the Henan Academy of Sciences under grant No.241841219。
文摘In this paper,we study the rotation curves of the Milky Way galaxy and Andromeda galaxy(M31)by considering their bulge,disk,and halo components.We model the bulge region by the widely accepted de Vaucouleur’s law and the disk region by the well established exponential profile.In order to understand the distribution of dark matter in the halo region,we consider three different dark matter profiles in the framework of the standardΛCDM model namely,Navarro-Frenk-White(NFW),Hernquist and Einasto profiles.We use recent data sets of rotation curves of the Milky Way and Andromeda galaxy.The data consist of rotation velocities of the stars and gas in the galaxy as a function of the radial distance from the center.Using Bayesian statistics,we perform an overall fit including all the components,i.e.,bulge,disk and halo with the data.Our results indicate that the NFW and Hernquist profiles are in concordance with the observational data points.However,the Einasto profile poorly explains the behavior of dark matter in both the galaxies.
