查看更多>>摘要：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 perturbation.Additionally,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.
查看更多>>摘要：This study focuses on the effects of a polytropic fluid on a charged gravitational source within f(T)gravity,where T is the torsion scalar.We investigate how the electromagnetic field affects the flow of energy in spherically symmetric and static celestial objects that contain relativistic fluids.By using the gravitational decoupling technique,we analyze the effects of polytropic fluid on the dynamics of the gravitational source,accompanied by the matching of the interior geometry with an exterior at the hypersurface Σ.Finally,with the help of the Tolman Ⅳsolution,we observe the conduct of energy conditions with the existence of charge using f(T)field equations and got the intended outcomes.
查看更多>>摘要：We explore the variable generalized Chaplygin gas(VGCG)model in the theory of matter creation cosmology within the framework of a spatially homogeneous and isotropic flat Friedmann—Lemaitre—Robertson—Walker space-time.Matter creation cosmology is based on reinterpretation of the energy-momentum tensor in Einstein's field equations.This creation corresponds to an irreversible energy flow from the gravitational field to the created matter constituents.The variable Chaplygin gas(VCG)is also studied as a particular solution.We use the Markov chain Monte Carlo method to constrain the free parameters of three models,namely,Lambda-Cold-Dark matter(ΛCDM),VGCG and VCG models with and without matter creation from the latest observational data from baryon acoustic oscillations,cosmic chronometer,type Ⅰa supernovae(Pantheon)including gamma-ray bursts,quasars and the local measurement of H0 from R21 data.Two different combinations of dataset provide a fairly tight constraint on the parameters of the ΛCDM,VGCG and VCG models.The present values of various cosmological parameters are obtained,which are very close to the ΛCDM model.Furthermore,we perform stability analysis,Bayesian evidence analysis and information criteria analysis for these models through studying the sound speed,Bayes factor,and Akaike information criteria(AIC)and Bayesian information criteria(BIC)selection criteria.The values of sound speed for VGCG and VCG models shows that both the models are stable.According to AIC,it is observed that VGCG and VCG models with matter creation are supported considerably less by current observations,while BIC shows that these models are not favoured by observational data.
查看更多>>摘要：The quantum hydrodynamic model for electrons and ions and the generalized hydrodynamic model for the strongly coupled dust particles are proposed in the strongly coupled quantum dusty plasma,where the combined quantum effects of quantum diffraction,quantum statistic pressure,as well as electron exchange and correlation effects are all considered in the quantum hydrodynamic model.The shear and bulk viscosity effects are included in the viscoelastic relaxation,which leads to the decay of the dust-ion-acoustic waves.The approximate time-dependent solitary solution is obtained by the momentum conservation law in the presence of viscosity.
查看更多>>摘要：For the dynamics of three-dimensional electron-positron-ion plasmas,a fluid quantum hydrodynamic model is proposed by considering Landau quantization effects in dense plasma.Ion-neutral collisions in the presence of the Coriolis force are also considered.The application of the reductive perturbation technique produces a wave evolution equation represented by a damped Korteweg-de Vries equation.This equation,however,is insufficient for describing waves in our system at very low dispersion coefficients.As a result,we considered the highest-order perturbation,which resulted in the damped Kawahara equation.The effects of the magnetic field,Landau quantization,the ratio of positron density to electron density,the ratio of positron density to ion density,and the direction cosine on linear dispersion laws as well as soliton and conoidal solutions of the damped Kawahara equation are explored.The understanding from this research can contribute to the broader field of astrophysics and aid in the interpretation of observational data from white dwarfs.
Carlos Magno O PereiraFrankbelson dos S AzevedoLuís Fernando C PereiraEdilberto O Silva...
151-157页
查看更多>>摘要：In this article,we investigate the nonrelativistic quantum motion of a charged particle within a rotating frame,taking into account the Aharonov-Bohm(AB)effect and a uniform magnetic field.Our analysis entails the derivation of the equation of motion and the corresponding radial equation to describe the system.Solving the resulting radial equation enables us to determine the eigenvalues and eigenfunctions,providing a clear expression for the energy levels.Furthermore,our numerical analysis highlights the substantial influence of rotation on both energy levels and optical properties.Specifically,we evaluate the photoionization cross-section with and without the effects of rotation.To elucidate the impact of rotation on the photoionization process of the system,we present graphics that offer an appealing visualization of the intrinsic nature of the physics involved.
查看更多>>摘要：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 attractor.For 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.
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