# Kimet JusufiUniversity of Tetova · Department of Physics

Kimet Jusufi

PhD in Physics

## About

160

Publications

35,278

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3,158

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Citations since 2016

Introduction

General Relativity, Quantum mechanics.

Additional affiliations

January 2011 - April 2016

## Publications

Publications (160)

We study the gravitational deflection of relativistic massive particles by Janis-Newman-Winicour (JNW) spacetimes (also known as a rotating source with a surface-like naked singularity), and a rotating Kerr-like wormholes. Based on the recent article [K. Jusufi, Phys. Rev. D 98, 064017 (2018)], we extend some of these results by exploring the effec...

We consider the problem of gravitational deflection of a propagating relativistic massive particles by rotating black holes (Kerr black holes) and rotating wormholes (Teo wormholes) in the weak limit approximation. In particular we have introduced an alternative way to calculate the deflection angle for massive particles based on the refractive ind...

The presence of dark matter around a black hole remarkably affects its spacetime. We consider the effects of dark matter on the shadow of a new solution to the Einstein equations that describes a rotating black hole in the background of perfect dark matter fluid (PFDM), along with its extension to nonzero cosmological constant Λ. Working in Boyer-L...

We study a Kerr-like black hole and naked singularity in perfect fluid dark matter (PFDM). The critical value of spin parameter a c is presented to differentiate the black hole from naked singularity. It is seen that for any fixed value of dark matter parameter α the rotating object is black hole if a ≤ a c and naked singularity if a > a c. Also fo...

Weak gravitational lensing by black holes and wormholes in the context of massive gravity (Be-bronne and Tinyakov 2009) theory is studied. The particular solution examined is characterized by two integration constants, the mass M and an extra parameter S namely 'scalar charge'. These black hole reduce to the standard Schwarzschild black hole soluti...

In this paper, we present a family of regular black hole solutions in the presence of charge and angular momentum. We also discuss the related thermodynamics and we comment about the black hole life cycle during the balding and spin down phases. Interestingly the static solution resembles the Ayón-Beato–García spacetime, provided the T-duality scal...

We use observational data from the S2 star orbiting around the Galactic Center to constrain a black hole solution of extended teleparallel gravity models. Subsequently, we construct the shadow images of Sgr A⋆ black hole. In particular, we constrain the parameter α=1/λ which appears in the Born–Infeld f(T) model. In the strong gravity regime we fin...

The aim of the paper is twofold: First, we generalize the non-relativistic Horava–Lifshitz four-dimensional black hole solution to include the electric charge to show a correspondence with the charged AdS solution in four-dimensional Einstein Gauss–Bonnet theory, and then we explore the phenomenological aspects of this black hole solution. Among ot...

We employ Verlinde's entropic force scenario to extract the modified Friedmann equations by taking into account the zero-point length correction to the gravitational potential. Starting form the modified gravitational potential due to the zero-point length, we first find the logarithmic corrections to the entropy expression and then we derive the m...

In this paper, by means of regularisation procedure via $r\to \sqrt{r^2+l_0^2}$ (where $l_0$ can play the role of zero point length), we first modify the gravitational and electromagnetic potentials in two dimensions and then we solve the Einstein field equations to end up with an exact and regular black hole solution in three dimensions with a neg...

We investigate the null geodesics and the shadow cast by the Kerr-Newman-Kiselev-Letelier (KNKL) black hole for the equation of state parameter $\omega_q=-2/3$ and for different values of the spacetime parameters, including the quintessence parameter $\gamma$, the cloud of string (CS) parameter $b$, the spin parameter $a$ and the charge $Q$ of the...

We investigate the null geodesics and the shadow cast by the Kerr–Newman–Kiselev–Letelier (KNKL) black hole for the equation of state parameter ωq=-2/3 and for different values of the spacetime parameters, including the quintessence parameter γ, the cloud of string (CS) parameter b, the spin parameter a and the charge Q of the black hole. We notice...

In this paper, we construct a class of charged and regular black hole solutions in Verlinde's Emergent Gravity (VEG). In particular, these solutions include, black holes with asymptotically Minkowski core, T-duality, Frolov/Simpson-Visser type solutions, as well as the Bardeen/Hayward type solutions as a special case. Using the relation between the...

We study the dynamics of test particles around a magnetized Ernst black hole considering its magnetic field in the environment surrounding the black hole. We show how its magnetic field can influence the dynamics of particles and epicyclic motion around the black hole. Based on the analysis, we find that the radius of the innermost stable circular...

In this paper we study the possibility of having a wormhole (WH) as a candidate for the Sgr A $$^\star $$ ⋆ central object and test this idea by constraining their geometry using the motion of S2 star and the reconstructed shadow images. In particular, we consider three WH models, including WHs in Einstein theory, brane-world gravity, and Einstein–...

We study the Hawking evaporation process of the exact black hole with nonlinear electrodynamics for positive and negative coupling constant $$\zeta $$ ζ . We provide a new perspective to study the thermodynamics of exact black hole through deflection angle formalism. We also evaluate the shadow images in the presence of deflection images for this b...

Using a modified expression for the electric potential in the context of string T-duality we obtain an exact charged solution within 4D Einstein-Gauss-Bonnet (4D EGB) theory of gravity in the presence of a cosmological constant. We show that the solution exists in the regularized 4D EGB thoery as well. The black hole solution is regular and free fr...

The consequences of the quantum fluctuations have leading role in high-energy physics. These fluctuations often regarded as a correction of the infrared limit and contribute to the stability conditions of the black holes. In this work, we provide the deep study of effects of thermal fluctuations on a generalized class of regular black holes. In ord...

In this paper, we present a family of regular black hole solutions in the presence of charge and angular momentum. We also discuss the related thermodynamics and we comment about the black hole life cycle during the balding and spin down phases. Interestingly the static solution resembles the Ay\'on-Beato--Garc\'ia spacetime, provided the T-duality...

We use observational data from the S2 star orbiting around the Galactic Center to constrain a black hole solution of extended teleparallel gravity models. Subsequently, we construct the shadow images of Sgr A ⋆ black hole. In particular, we constrain the parameter α = 1/λ which appears in the Born-Infeld f (T) model. In the strong gravity regime we...

Horizon-scale images of black holes (BHs) and their shadows have opened an unprecedented window onto tests of gravity and fundamental physics in the strong-field regime. We consider a wide range of well-motivated deviations from classical General Relativity (GR) BH solutions, and constrain them using the Event Horizon Telescope (EHT) observations o...

We study the dynamics of test particles around a static and spherically symmetric magnetized Ernst black hole considering its magnetic field in the environment surrounding the black hole. We show how its magnetic filed can influence on the dynamics of particles and epicyclic motions around the black hole. Based on the analysis we find that the radi...

In this paper we focus on the relation between quasinormal modes (QNMs) and a rotating black hole shadows. As a specific example, we consider the quantum deformed Kerr black hole obtained via Newman--Janis--Azreg-A\"{\i}nou algorithm. In particular, using the geometric-optics correspondence between the parameters of a QNMs and the conserved quantit...

In this paper, we focus on the relation between quasinormal modes (QNMs) and a rotating black hole shadow. As a specific example, we consider the quantum deformed Kerr black hole obtained via Newman–Janis–Azreg-Aïnou algorithm. In particular, using the geometric-optics correspondence between the parameters of a QNMs and the conserved quantities alo...

We construct an effective four-dimensional string-corrected black hole (4D SCBH) by rescaling the string coupling parameter in a D-dimensional Callan–Myers–Perry black hole. From the theoretical point of view, the most interesting findings are that the string corrections coincide with the so-called generalized uncertainty principle (GUP) correction...

We construct an effective four dimensional string-corrected black hole (4D SCBH) by rescaling the string coupling parameter in a $D$-dimensional Callan-Myers-Perry black hole. From the theoretical point of view, the most interesting findings are that the string corrections coincide with the so-called generalized uncertainty principle (GUP) correcti...

In this article, we study the particle dynamics around a static and spherically symmetric Bardeen-Kiselev black hole (BK BH) which is a solution of the Einstein-non-linear Maxwell field equations along with a quintessential field. We discuss its essential geometrical properties such as scalar invariants and size of innermost stable circular orbits....

We use data from M87* central black hole shadow, as well as from the S2 star observations, in order to extract constraints on Barrow entropy. The latter is a modified entropy arising from quantum-gravitational effects on the black hole horizon, quantified by the new parameter Δ. Such a change in entropy leads to a change in temperature, as well as...

We compare the optical appearance of a thin accretion disk in the Simpson-Visser spacetime to the Schwarzschild black hole case in this paper. We calculate and illustrate the redshift and observed flux distributions as viewed by distant observers at various inclination angles. Simpson-Visser family of metrics creates Novikov-Thorne (NT) accretion d...

In this article, we study the particle dynamics around a static and spherically symmetric Bardeen-Kiselev black hole (BK BH) which is a solution of the Einstein-non-linear Maxwell field equations along with a quintessential field. We discuss its essential geometrical properties such as scalar invariants and size of innermost stable circular orbits....

We use data from M87* central black hole shadow, as well as from the S2 star observations, in order to extract constraints on Barrow entropy. The latter is a modified entropy arising from quantum-gravitational effects on the black hole horizon, quantified by the new parameter $\Delta$. Such a change in entropy leads to a change in temperature, as w...

In this paper we study the accretion of matter onto the black holes and the shadow images obtained by an infalling accretion flow of gas in a theory of massive gravity with a spontaneously breaking Lorentz symmetry. This black hole solution is characterized by mass M, scalar charge S, and the parameter λ. In order to extract the astrophysical resul...

We compare the optical appearance of a thin accretion disk in the Simpson-Visser spacetime to the Schwarzschild black hole case in this paper. We calculate and illustrate the red-shift and observed flux distributions as viewed by distant observers at various inclination angles. Simpson-Visser family of metrics create Novikov-Thorne (NT) accretion d...

In this paper we study the accretion of matter onto the black holes and the shadow images obtained by an infalling accretion flow of gas in a theory of massive gravity (MG) with a spontaneously breaking Lorentz symmetry. This black hole solution is characterized by mass M, scalar charge S and the parameter λ. In order to extract the astrophysical r...

In this paper we study the accretion of matter onto the black holes and the shadow images obtained by an infalling accretion flow of gas in a theory of massive gravity (MG) with a spontaneously breaking Lorentz symmetry. This black hole solution is characterized by mass $M$, scalar charge $S$ and the parameter $\lambda$. In order to extract the ast...

In this paper, we study the influence of the axion-plasmon, as proposed in (Phys. Rev. Lett. 120, 181803 (2018)) on the optical properties of the Schwarzschild black hole. Our aim is to provide a test to detect the effects of a fixed axion background using black holes. To accomplish our goal, we explore the effect of the axion-plasmon coupling on t...

In this paper we study the correspondence between the real part of quasinormal modes and the shadow radius in a wormhole spacetime. Firstly we consider the above correspondence in a static and spherically symmetric wormhole spacetime and then explore this correspondence numerically by considering different wormhole models having specific redshift f...

This paper explores the influence of special type of higher order generalized uncertainty principle on the thermodynamics of five-dimensional black hole in Einstein–Gauss–Bonnet gravity coupled to nonlinear electrodynamics. We examine the corrected thermodynamical properties of the black hole with some interesting limiting cases [Formula: see text]...

In this paper we study the possibility of having a wormhole (WH) as a candidate for the Sgr A$^\star$ central object and test this idea by constraining their geometry using the motion of S2 star and the reconstructed shadow images. In particular, we consider three WH models, including WHs in Einstein theory, brane-world gravity, and Einstein-Dirac-...

DOI:https://doi.org/10.1103/PhysRevD.103.089902

In this paper, we investigate the effects of a dark matter (DM) spike on the neighborhood of Sgr A*, the black hole (BH) in the center of the Milky Way galaxy. Our main goal is to investigate whether current and future astronomical observations of Sgr A* could detect the presence of such a DM spike. At first, we construct the spacetime metric aroun...

We study the effect of baryonic matter and apparent dark matter on black hole shadow in Verlinde’s Emergent Gravity. To do so, we consider different baryonic mass profiles and an optically-thin disk region described by a gas in a radial free fall around the black hole. Assuming that most of the baryonic matter in the galaxy is located near the gala...

In this paper, we obtain an effective metric describing a regular and rotating magnetic black hole (BH) solution with a Yang-Mills electromagnetic source in Einstein-Yang-Mills (EYM) theory using the Newman-Janis (NJ) algorithm via the noncomplexification radial coordinate procedure. We then study the BH shadow and the quasinormal modes (QNMs) for...

In this paper we study the shadow of rotating Kaluza-Klein (KK) black holes and the connection between the shadow radius and the real part of quasinormal modes (QNMs) in the eiokonal limit. In addition we have explored the quasiperiodic oscillations (QPOs) in the rotating KK black hole.

In this paper we study the shadow of rotating KK black holes and the connection between theshadow radius and the real part of quasi-normal modes (QNMs) in the eiokonal limit. In addition we have explored the quasi-periodic oscillations (QPOs) in the rotating KK black hole.

We study the effect of baryonic matter and apparent dark matter on black hole shadow in Ver-linde's Emergent Gravity. To do so, we consider different baryonic mass functions and an optically-thin disk region described by a gas in a radial free fall around the black hole. Assuming that most of the baryonic matter in the galaxy is located near the ga...

In this paper we study the shadow of rotating Kaluza-Klein (KK) black holes and the connection between the shadow radius and the real part of quasi-normal modes (QNMs) in the eiokonal limit. In addition we have explored the quasi-periodic oscillations (QPOs) in the rotating KK black hole.

We study the possibility of identifying dark matter in the galactic center from the physical properties of the electromagnetic radiation emitted from a optical-thin disk region around a static and spherically symmetric black hole. In particular, we consider two specific models for the optical-thin disk region: a gas at rest and a gas in a radial fr...

We study the possibility of identifying dark matter in the galactic center from the physical properties of the electromagnetic radiation emitted from a optical-thin disk region around a static and spherically symmetric black hole. In particular, we consider two specific models for the optical-thin disk region: a gas at rest and a gas in a radial fr...

We study quasinormal modes (QNMs) in a five-dimensional electrically charged Bardeen black hole spacetime by considering the scalar and electromagnetic field perturbations. The black hole spacetime is an exact solution of Einstein gravity coupled to nonlinear electrodynamics in five dimensions, which has nonsingular behavior. To calculate QNMs, we...

In this paper we study the effect of the Generalized Uncertainty Principle (GUP) on the shadow of GUP-modified Kerr black hole and the correspondence between the shadow radius and the real part of the quasinormal modes (QNMs). We find that the shadow curvature radius of the GUP-modfied Kerr black hole is bigger compared to the Kerr vacuum solution...

In this paper we obtain an effective metric describing a regular and rotating magnetic black hole (BH) solution with a Yang-Mills electromagnetic source in Einstein-Yang-Mills (EYM) theory using the Newman-Janis algorithm via the non-complexification radial coordinate procedure. We then study the BH shadow and the quasinormal modes (QNMs) for massl...

In this paper we study the effect of the Generalized Uncertainty Principle (GUP) on the shadow of GUP-modified Kerr black hole and the correspondence between the shadow radius and the real part of the quasinormal modes (QNMs). We find that the shadow curvature radius of the GUP-modfied Kerr black hole is bigger compared to the Kerr vacuum solution...

In this paper we obtain an effective metric describing a regular and rotating magnetic black hole (BH) solution with a Yang-Mills electromagnetic source in Einstein-Yang-Mills (EYM) theory using the Newman--Janis algorithm via the non-complexification radial coordinate procedure. We then study the BH shadow and the quasinormal modes (QNMs) for mass...

In this paper we study the correspondence between the real part of quasinormal modes (QNMs) and the shadow radius in a wormhole spacetime. Firstly we consider the above correspondence in a static and spherically symmetric wormhole spacetime and then explore this correspondence numerically by considering different wormhole models having specific red...

Recent times witnessed a significant interest in regularizing, a \( D \rightarrow 4 \) limit, of EGB gravity initiated by Glavan and Lin [Phys. Rev. Lett. 124, 081301 (2020)] by re-scaling GB coupling constant as \(\alpha /(D-4)\) and taking limit \(D \rightarrow 4\), and in turn these regularized 4D gravities have nontrivial gravitational dynamics...

In this paper we study the correspondence between the real part of quasinormal modes (QNMs) and the shadow radius in a wormhole spacetime. Firstly we consider the above correspondence in a static and spherically symmetric wormhole spacetime and then explore this correspondence numerically by considering different wormhole models having specific red...

We study the quasinormal modes (QNMs) of the 5D electrically charged Bardeen black holes by considering the scalar and the electromagnetic field perturbations. The black holes spacetime is an exact solution of the Einstein gravity coupled to the nonlinear electrodynamics in five dimensions which has nonsingular behavior. In order to calculate the Q...

We study the quasinormal modes (QNMs) of the 5D electrically charged Bardeen black holes by considering the scalar and the electromagnetic field perturbations. The black holes spacetime is an exact solution of the Einstein gravity coupled to the nonlinear electrody-namics in five dimensions which has nonsingular behavior. In order to calculate the...

In this paper we construct a black hole solution surrounded by superfluid dark matter (BH-SFDM) and baryonic matter, and study their effects on the shadow images of the Sgr A$^{*}$ black hole. To achieve this goal, we have considered two density profiles for the baryonic matter described by the spherical exponential profile and the power law profil...

In this letter we present an exact spherically symmetric and magnetically charged black hole solution with exponential model of nonlinear electrodynamics [S. Kruglov, Annals Phys. 378, 59-70 (2017)] in the context of 4D Einstein-Gauss-Bonnet (EGB) gravity. We show that our −ve branch, in the limit of GB coupling coefficient α → 0 and the nonlinear...

In this paper we construct a black hole solution surrounded by superfluid dark matter and baryonic matter, and study their effects on the shadow images of the Sgr A * black hole. To achieve this goal, we have considered two density profiles for the baryonic matter described by the spherical exponential profile and the power law profile including a...

In this letter we present an exact spherically symmetric and magnetically charged black hole solution with exponential model of nonlinear electrodynamics [S. Kruglov, Annals Phys. 378, 59-70 (2017)] in the context of 4D Einstein-Gauss-Bonnet (EGB) gravity. We show that our $-$ve branch, in the limit of GB coupling coefficient $\alpha \rightarrow 0$...

In this paper we first highlight a simple connection between the real part of QNMs frequencies (QNMs) and shadow radius of BHs and then explore the effect of dark matter on the QNMs of mass-less scalar field, electromagnetic and gravitational field perturbations in a black hole (BH) spacetime surrounded by perfect fluid dark matter (BHPFDM). Using...

Recently Glavan and Lin [Phys. Rev. Lett. 124, 081301 (2020)] formulated the Einstein-Gauss-Bonnet (EGB) gravity by re-scaling GB coupling constant as α/(D − 4) and taking limit D → 4 at the level of field equations. The GB contribution, in the resulting novel 4D EGB theory, makes a nontrivial contribution and the theory preserves the number of deg...

Recently Glavan and Lin [Phys. Rev. Lett. 124, 081301 (2020)] formulated the Einstein-Gauss-Bonnet (EGB) gravity by re-scaling GB coupling constant as $\alpha/(D-4)$ and taking limit $D \to 4$ at the level of field equations. The GB contribution, in the resulting novel 4D EGB theory, makes a nontrivial contribution and the theory preserves the numb...

Based on the geometric-optics correspondence between the parameters of a quasinormal mode and the conserved quantities along geodesics, we propose an equation to calculate the typical shadow radius for asymptotically flat and rotating black holes when viewed from the equatorial plane given byR s = √ 2 2 r + 0 f (r)| r + 0 + r − 0 f (r)| r − 0 ...

Based on the geometric-optics correspondence between the parameters of a quasinormal mode and the conserved quantities along geodesics, we propose an equation to calculate the typical shadow radius for asymptotically flat and rotating black holes when viewed from the equatorial plane given by \begin{equation}\notag \bar{R}_s=\frac{\sqrt{2}}{2}\left...

In this paper, we construct an effective rotating loop quantum black hole (LQBH) solution, starting from the spherical symmetric LQBH by applying the Newman-Janis algorithm modified by Azreg-Aïnou’s noncomplexification procedure, and study the effects of loop quantum gravity (LQG) on its shadow. Given the rotating LQBH, we discuss its horizon, ergo...

In this paper, we construct an effective rotating loop quantum black hole (LQBH) solution, starting from the spherical symmetric LQBH by applying the Newman-Janis algorithm modified by Azreg-Aïnou's non-complexification procedure, and study the effects of loop quantum gravity (LQG) on its shadow. Given the rotating LQBH, we discuss its horizon, erg...