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Irina Radinschi

Publications and source records attributed to Irina Radinschi.

17 recordsLinked to original sources
arXiv2024

Reconstruction schemes of scalar field models for the Power Law Entropy Corrected Holographic Dark Energy model with Ricci scalar cut-off

In this work, we examine the cosmological characteristics of the Power Law Entropy Corrected Holographic Dark Energy (PLECHDE) model with infrared (IR) cut-off, which is determined by the curvature parameter $k$, the time derivative of $H$, and the average radius of the Ricci scalar curvature $R$, which varies with the Hubble parameter $H$ squared. We obtain the deceleration parameter $q$ and the Equation of State (EoS) parameter of Dark Energy (DE) $ω_D$. Additionally, we derive the Hubble parameter $H$ and the scale factor $a$ expressions as functions of the cosmic time $t$. Additionally, we examine the limiting scenario that pertains to a flat Dark Dominated Universe. Furthermore, we establish a correspondence between the DE model considered and some scalar fields, in particular the Generalized Chaplygin Gas, the Modified Chaplygin Gas, the Modified Variable Chaplygin Gas, the New Modified Chaplygin Gas, the Viscous Generalized Chaplygin Gas, the Dirac-Born-Infeld, the Yang-Mills, and the Non Linear Electrodynamics scalar field models.

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arXiv2021

Analytical model of low mass strange stars in 2+1 spacetime

The low mass compact stars are quite fascinating objects to study for their enigmatic behaviour. In this paper, we have modeled this kind of low mass strange stars based on the Heintzmann ansatz (H. Heintzmann., Zeitschrift für Physik, vol.228, 489, 1969.) in $(2+1)$ dimension. Attractive anisotropic force plays a significant role to restrict the upper mass limit (which is comparatively low) of the strange star. We have applied our model to some low mass strange stars. Our model could be useful to predict the important parameters of the low mass strange stars.

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arXiv2018

Localization of Energy-Momentum for a Black Hole Spacetime Geometry with Constant Topological Euler Density

The evaluation of the energy-momentum distribution for a new four-dimensional, spherically symmetric, static and charged black hole spacetime geometry with constant non-zero topological Euler density is performed by using the energy-momentum complexes of Einstein and Møller. This black hole solution was recently developed in the context of the coupled Einstein--non-linear electrodynamics of the Born-Infeld type. The energy is found to depend on the mass $M$ and the charge $q$ of the black hole, the cosmological constant $Λ$ and the radial coordinate $r$, while in both prescriptions all the momenta vanish. Some limiting and particular cases are analyzed, illustrating the rather extraordinary character of the spacetime geometry considered.

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arXiv2018

Particle motion around charged black holes in generalized dilaton-axion gravity

The behaviour of massive and massless test particles around asymptotically flat and spherically symmetric, charged black holes in the context of generalized dilaton-axion gravity in four dimensions is studied. All the possible motions are investigated by calculating and plotting the corresponding effective potential for the massless and massive particles as well. Further, the motion of massive (charged or uncharged) test particles in the gravitational field of charged black holes in generalized dilaton-axion gravity for the cases of static and non-static equilibrium is investigated by applying the Hamilton-Jacobi approach.

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arXiv2012

Singularity free stars in (2+1) dimensions

We present some new types of non-singular model for anisotropic stars with constant $Λ$ and variable $Λ$ based on the Krori and Barua (KB) metric in $(2+1)$ dimensions. The solutions obtained here satisfy all the regularity conditions and its simple analytical form helps us to study the various physical properties of the configuration.

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arXiv2012

Energy-Momentum Localization for a Space-Time Geometry Exterior to a Black Hole in the Brane World

In general relativity one of the most fundamental issues consists in defining a generally acceptable definition for the energy-momentum density. As a consequence, many coordinate-dependent definitions have been presented, whereby some of them utilize appropriate energy-momentum complexes. We investigate the energy-momentum distribution for a metric exterior to a spherically symmetric black hole in the brane world by applying the Landau-Lifshitz and Weinberg prescriptions. In both the aforesaid prescriptions, the energy thus obtained depends on the radial coordinate, the mass of the black hole and a parameter $λ_{0}$, while all the momenta are found to be zero. It is shown that for a special value of the parameter $λ_{0}$, the Schwarzschild space-time geometry is recovered. Some particular and limiting cases are also discussed.

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arXiv2012

Distribution of Energy-Momentum in a Schwarzschild-Quintessence Space-time Geometry

An analysis of the energy-momentum localization for a four-dimensional\break Schwarzschild black hole surrounded by quintessence is presented in order to provide expressions for the distributions of energy and momentum. The calculations are performed by using the Landau-Lifshitz and Weinberg energy-momentum complexes. It is shown that all the momenta vanish, while the expression for the energy depends on the mass $M$ of the black hole, the state parameter $w_{q}$ and the normalization factor $c$. The special case of $w_{q}=-2/3$ is also studied, and two limiting cases are examined.

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arXiv2011

Isotropic cases of static charged fluid spheres in general relativity

In this paper we study the isotropic cases of static charged fluid spheres in general relativity. For this purpose we consider two different specialization and under these we solve the Einstein-Maxwell field equations in isotropic coordinates. The analytical solutions thus we obtained are matched to the exterior Reissner-Nordström solutions which concern with the values for the metric coefficients $e^ν$ and $e^μ$. We derive the pressure, density, pressure-to-density ratio at the centre of the charged fluid sphere and boundary $R$ of the star. Our conclusion is that static charged fluid spheres provide a good connection to compact stars.

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arXiv2009

The Energy of Regular Black Hole in General Relativity Coupled to Nonlinear Electrodynamics

According to the Einstein, Weinberg, and Møller energy-momentum complexes, we evaluate the energy distribution of the singularity-free solution of the Einstein field equations coupled to a suitable nonlinear electrodynamics suggested by Ayón-Beato and García. The results show that the energy associated with the definitions of Einstein and Weinberg are the same, but Møller not. Using the power series expansion, we find out that the first two terms in the expression are the same as the energy distributions of the Reissner-Nordström solution, and the third term could be used to survey the factualness between numerous solutions of the Einstein field eqautions coupled to a nonlinear electrodynamics.

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arXiv2006

The Energy for 2+1 Dimensional Black Hole Solutions

The energy distributions of four 2+1 dimensional black hole solutions were obtained by using the Einstein and Møller energy-momentum complexes. while $r \to \infty$, the energy distributions of these four solutions become divergence.

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arXiv2004

On the Energy of Stringy Black Holes

It is well-known that one of the most interesting and challenging problems of General Relativity is the energy and momentum localization. There are many attempts to evaluate the energy distribution in a general relativistic system. One of the methods used for the energy and momentum localization is the one which used the energy-momentum complexes. After the Einstein work, a large number of definitions for the energy distribution was given. We mention the expressions proposed by Landau and Lifshitz, Papapetrou, Bergmann, Weinberg and Møller. The Einstein, Landau and Lifshitz, Papapetrou, Bergmann and Weinberg energy-momentum complexes are restricted to calculate the energy distribution in quasi-Cartesian coordinates. The energy-momentum complex of Møller gives the possibility to make the calculations in any coordinate system. In this paper we calculate the energy distribution of three stringy black hole solutions in the Møller prescription. The Møller energy-momentum complex gives us a consistent result for these three situations. Keywords: Møller energy-momentum complex, charged black hole solution in heterotic string theory PACS: 04. 20 Dw, 04. 70. Bw,

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arXiv2002

On the Difference of Energy between the Einstein and Møller Prescription

In some black hole solutions, these do not exist the same energy-momentum complexes associated with using definition of Einstein and Møller in given coordinates. Here, we consider the difference of energy between the Einstein and Møller prescription, and compare it with the energy density of those black hole solutions. We found out a special relation between the difference of energy between the Einstein and Møller prescription and the energy density for considered black hole solutions.

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arXiv2001

Energy associated with a static spherically symmetric nonsingular black hole

We evaluate the energy distributions of the Dymnikova space-time using the Weinberg, Papapetrou, and Møller energy-momentum complexes. This result sustain the importance of the energy-momentum complexes in the evaluation of the energy distribution of a given space-time. To compare the energy distributions obtained by using several definitions, these results show that the Einstein, Tolman, and Weinberg energy complexes are the same in Schwarzschild Cartesian coordinates, but the Papapetrou and the Møller are not.

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arXiv2000

Energy of a Conformal Scalar Dyon Black Hole

We obtain the energy of a conformal scalar dyon black hole (CSD) by using the energy-momentum complexes of Tolman and Møller. The total gravitational energy is given by the CSD charge in the both prescriptions.

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