Probing the Bardeen-Kiselev black hole with the cosmological constant caused by Einstein equations coupled with nonlinear electrodynamics using quasinormal modes and greybody bounds

In this work,we investigate a static and spherically symmetric Bardeen-Kiselev black hole(BH)with the cosmological constant,which is a solution of the Einstein-non-linear Maxwell field equations.We compute the quasinormal frequencies for the Bardeen-Kiselev BH with the cosmological constant due to electromagnetic and gravitational perturbations.By varying the BH parameters,we discuss the behavior of both real and imaginary parts of the BH quasinormal frequencies and compare these frequencies with the Reissner-Nordström-de Sitter BH surrounded by quintessence(RN-dSQ).Interestingly,it is shown that the responses of the Bardeen-Kiselev BH with the cosmological constant and the RN-dSQ under electromagnetic perturbations are different when the charge parameter q,the state parameter w and the normalization factor c are varied;however,for the gravitational perturbations,the responses of the Bardeen-Kiselev BH with the cosmological constant and the RN-dSQ are different only when the charge parameter q is varied.Therefore,compared with the gravitational perturbations,the electromagnetic perturbations can be used to understand nonlinear and linear electromagnetic fields in curved spacetime separately.Another interesting observation is that,due to the presence of Kiselev quintessence,the electromagnetic perturbations around the Bardeen-Kiselev BH with the cosmological constant damps faster and oscillates slowly;for the gravitational perturbations,the quasinormal mode decays slowly and oscillates slowly.We also study the reflection and transmission coefficients along with the absorption cross section in the Bardeen-Kiselev BH with the cosmological constant;it is shown that the transmission coefficients will increase due to the presence of Kiselev quintessence.

Slowly rotating Einstein-bumblebee black hole solution and its greybody factor in a Lorentz violation model

We obtain an exact slowly rotating Einstein-bumblebee black hole solution by solving the corresponding rr and tθ components of the gravitational field equations for both cases:A)b u=(0,b(r),0,0) and B) bu=(0,b(r),b(θ),0) .Then,we check the other gravitational field equations and the bumblebee field motion equations using this solution.We find that for case A,there indeed exists a slowly rotating black hole solution for an arbitrary LV(Lorentz violation)coupling constant l;however,for case B,this slowly rotating solution exists if and only if coupling constant l is as small as or smaller than angular momentum a.Thus far,no full rotating black hole solution has been published;hence,the Newman-Janis algorithm cannot be used to generate a rotating solution in the Einstein-bumblebee theory.This is similar to the Einstein-aether theory,wherein only some slowly rotating black hole solutions exist.To study the effects of this broken Lorentz symmetry,we consider the black hole greybody factor and find that,for angular index l=0 ,LV constant l decreases the effective potential and enhances the absorption probability,which is similar to the results for the non-minimal derivative coupling theory.

Quasi-normal modes,emission rate,and shadow of charged AdS black holes with perfect fluid dark matter

In this study,we comprehensively investigated charged AdS black holes surrounded by a distinct form of dark matter.In particular,we focused on key elements including the Hawking temperature,quasi-normal modes(QNMs),emission rate,and shadow.We first calculated the Hawking temperature,thereby identifying critical values such as the critical radius and maximum temperature of the black hole,essential for determining its phase transition.Further analysis focused on the QNMs of charged AdS black holes immersed in perfect fluid dark matter(PFDM)within the massless scalar field paradigm.Employing the Wentzel-Kramers-Brillouin(WKB)method,we accurately derived the frequencies of these QNMs.Additionally,we conducted a meticulous assessment of how the intensity of the PFDM parameterαinfluences the partial absorption cross sections of the black hole,along with a detailed study of the frequency variation of the energy emission rate.The pivotal role of geodesics in understanding astrophysical black hole characteristics is highlighted.Specifically,we examined the influence of the dark matter parameter on photon evolution by computing the shadow radius of the black hole.Our findings distinctly demonstrate the significant impact of the PFDM parameterαon the boundaries of this shadow,providing crucial insights into its features and interactions.We also provide profound insights into the intricate dynamics between a charged AdS black hole,novel dark matter,and various physical phenomena,elucidating their interplay and contributing valuable knowledge to the understanding of these cosmic entities.