查看更多>>摘要：We investigate the observational appearance of static and spherically symmetric hairy black holes in the framework of gravitational decoupling with the weak energy condition(WEC).Two types of thin illumination conditions are studied:spherical accretion and disk accretion.As the hairy parameter increases,the size of the photon sphere and photon rings in both models decreases,and the overall luminosity attenuation becomes more pronounced.In spherical accretion,the luminosity of infalling accretion is significantly lower than that of stationary accretion.In disk accretion the luminosity of the black hole is contributed by direct emission,the lensing ring and the photon ring.Employing four types of astrophysical disk luminosity model,we investigate the appearance of halos and note that their luminosities do not superimpose when the source is on or beyond the innermost stable circular orbit.
查看更多>>摘要：We study the relic density of asymmetric dark matter with long-range interactions by considering the Sommerfeld effect.We find that the annihilation cross section of asymmetric dark matter is enhanced by the Sommerfeld effect and thus the relic density is decreased.Then we use the Planck data to constrain the asymmetry factor,coupling,and to derive the upper bounds on the dark matter mass in s-wave and p-wave annihilation cases.
查看更多>>摘要：Approximate all-terrain spacetimes for astrophysical applications are presented.The metrics possess five relativistic multipole moments,namely,mass,rotation,mass quadrupole,charge,and magnetic dipole moment.All these spacetimes approximately satisfy the Einstein-Maxwell field equations.The first metric is generated using the Hoenselaers-Peijés method from given relativistic multipoles.The second metric is a perturbation of the Kerr-Newman metric,which makes it a relevant approximation for astrophysical calculations.The last metric is an extension of the Hartle-Thorne metric that is important for obtaining internal models of compact objects perturbatively.The electromagnetic field is calculated using Cartan forms for locally non-rotating observers.These spacetimes are relevant for inferring properties of compact objects from astrophysical observations.Furthermore,the numerical implementations of these metrics are straightforward,making them versatile for simulating potential astrophysical applications.
查看更多>>摘要：The Weyl double copy builds the relation between gauge theory and gravity theory,in particular the correspondence between gauge solutions and gravity solutions.In this paper,we obtain the slowly rotating charge solutions from the Weyl double copy for the Kerr black hole with small Chern-Simons correction.Based on the Weyl double copy relation,for the Petrov type D solution in Chem-Simons modified gravity,we find the additional correction to the electromagnetic field strength tensor of the rotating charge.For the Petrov type Ⅰ solution,we find that the additional electromagnetic field strength tensors have external sources,while the total sources vanish at the leading order.
查看更多>>摘要：In the quantized field formalism,using Kramers-Henneberger unitary transformation as the semi-classical counterpart of Block-Nordsieck transformation,the dynamics of entanglement during the low energy scattering processes in bi-partite systems at the presence of a laser beam fields are studied.The stationary-state Schrodinger equation for the quantum scattering process is obtained for such systems.Then,using partial wave analysis,we introduce a new form of entanglement fidelity considering the effect of high-intensity laser beam fields.The effective potential of hot quantum plasma including plasmon and quantum screening effects is used to obtain the entanglement fidelity ratio as a function of the laser amplitude,and plasmon and Debye length parameters for the elastic electron-ion collisions.It is shown that the plasma free electrons oscillations under interaction with laser beam fields improve the correlations between charged particles and consequently lead to the increase in the system entanglement.
查看更多>>摘要：The emerging concept of multi-caloric effects,introduced in 2010,entails the application of multiple interplay fields to a thermodynamic system.While multi-caloric effects are the main focus of experimental endeavors,theoretical considerations fall short of providing a thorough understanding.This paper introduces a comprehensive presentation on multi-caloric effects,employing the method and theory of exterior derivative formations.It addresses every aspect of thermodynamic systems,showcasing its applicability to multi-caloric materials(both single-phase and multi-phase materials),and its adaptability to different scenarios(either in single or multiple force fields).The formulation of Maxwell relationships,characterized by their generality and universality,enables a clear prediction in entropy and temperature,facilitating a distinct identification between independent and interdependent contributions from multi-caloric effects.These insights hold significant importance in designing and developing specialized thermodynamic materials,optimizing functional performances and exploring innovative mechanisms.
查看更多>>摘要：A multi-relaxation-time discrete Boltzmann model(DBM)with split collision is proposed for both subsonic and supersonic compressible reacting flows,where chemical reactions take place among various components.The physical model is based on a unified set of discrete Boltzmann equations that describes the evolution of each chemical species with adjustable acceleration,specific heat ratio,and Prandtl number.On the right-hand side of discrete Boltzmann equations,the collision,force,and reaction terms denote the change rates of distribution functions due to self-and cross-collisions,external forces,and chemical reactions,respectively.The source terms can be calculated in three ways,among which the matrix inversion method possesses the highest physical accuracy and computational efficiency.Through Chapman-Enskog analysis,it is proved that the DBM is consistent with the reactive Navier-Stokes equations,Fick's law and the Stefan-Maxwell diffusion equation in the hydrodynamic limit.Compared with the one-step-relaxation model,the split collision model offers a detailed and precise description of hydrodynamic,thermodynamic,and chemical nonequilibrium effects.Finally,the model is validated by six benchmarks,including multicomponent diffusion,mixture in the force field,Kelvin-Helmholtz instability,flame at constant pressure,opposing chemical reaction,and steady detonation.
查看更多>>摘要：Nickel-based single-crystal superalloys are crucial materials for the preparation of aero-engine turbine blades.Many solute elements are added to superalloys for strengthening.However,the relationship between the clustering behavior of solute atoms and the properties of nickel-based single-crystal superalloys is still unclear.Herein,we conduct first-principles calculations onγ phases with Mo-Mo and Mo-Mo-Ru clusters to reveal the possibility and stabilizing mechanism of solute clusters.Introducing Mo lowers the total energy,binding energy,and formation energy of the γ phase due to the replacement of weak Ni-Ni interaction with strong Mo-Ni bonding.Note that the γ phase containing the Mo-Mo cluster is more stable than that containing a Mo single atom,possibly owing to a wide affecting range.The Ru atom added to the γ phase can further boost system stability,and it tends to form a Mo-Mo-Ru cluster.The stabilizing impact of the Mo-Mo-Ru cluster is demonstrated to be the replacement of weak Ni-Mo interaction by the strong Ru-Mo interaction,which may be derived from the enhanced d-orbital hybridization.
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