Stability of Charged Thin-Shell Wormholes in (2+1) Dimensions

In this paper, we construct thin-shell wormholes in (2 + 1)-dimensions from noncommutative BTZ black hole by applying the cut-and-paste procedure implemented by Visser. We calculate the surface stresses localized at the wormhole throat by using the Darmois–Israel formalism and we find that the wormholes are supported by matter violating the energy conditions. In order to explore the dynamical analysis of the wormhole throat, we consider that the matter at the shell is supported by dark energy equation of state (EoS) p = ωρ with ω < 0. The stability analysis is carried out of these wormholes to linearized spherically symmetric perturbations around static solutions. Preserving the symmetry we also consider the linearized radial perturbation around static solution to investigate the stability of wormholes which was explored by the parameter β (speed of sound).

Spherically symmetric thin-shell wormholes in the presence of a cosmological constant are constructed applying the cut-and-paste technique implemented by Visser. Using the Darmois–Israel formalism the surface stresses, which are concentrated at the wormhole throat, are determined. This construction allows us to apply a dynamical analysis to the throat, considering linearized radial perturbations around static solutions. For a large positive cosmological constant, i.e., for the Schwarzschild–de Sitter solution, the region of stability is significantly increased, relatively to the null cosmological constant case, analysed by Poisson and Visser. With a negative cosmological constant, i.e., the Schwarzschild–anti de Sitter solution, the region of stability is decreased. In particular, considering static solutions with a generic cosmological constant, the weak and dominant energy conditions are violated, while for a0 ⩽ 3M the null and strong energy conditions are satisfied. The surface pressure of the static solution is strictly positive for the Schwarzschild and Schwarzschild–anti de Sitter spacetimes, but takes negative values, assuming a surface tension in the Schwarzschild–de Sitter solution, for high values of the cosmological constant and the wormhole throat radius.

In this paper, we study two different models of dark energy based on Chaplygin gas equation of state. The first model is the variable modified Chaplygin gas while the second one is the extended Chaplygin gas. Both models are considered in the framework of higher order $f(R)$ modified gravity. We also consider the case of time varying gravitational constant $G$ and $\Lambda$ for both models. We investigate some cosmological parameters such as the Hubble, the deceleration and the equation of state parameters. Then we showed that the model that we considered, extended Chaplygin gas with time-dependent $G$ and $\Lambda$, is consistent with the observational data. Finally we conclude with the discussion of cosmological perturbations of our model.

We review the essential features of the Chaplygin gas cosmological models and provide some examples of appearance of the Chaplygin gas equation of state in modern physics. A possible theoretical basis for the Chaplygin gas in cosmology is discussed. The relation with scalar field and tachyon cosmological models is also considered.

We review the essential features of the Chaplygin gas cosmological models and provide some examples of appearance of the Chaplygin gas equation of state in modern physics. A possible theoretical basis for the Chaplygin gas in cosmology is discussed. The relation with scalar field and tachyon cosmological models is also considered.

Semi-hyperbolic patches of solutions to the two-dimensional nonlinear wave system for Chaplygin gases

We investigate an interacting two-fluid model in a spatially flat Friedmann–Lemaître–Robertson–Walker (FLRW) Universe, when the energy transfer between these two dark components is produced by a factorizable nonlinear sign-changeable interaction depending linearly on the energy density and quadratically on the deceleration parameter. We solve the source equation and obtain the effective energy densities of the dark sector and their components. We show that the effective equation of state of the dark sector includes some of the several kinds of Chaplygin gas equations of state as well as a generalization of the polytropic equation of state. We use Bayesian statistics methods to constrain free parameters in the models during the most recent evolution considering supernovae type Ia and measurements of the Hubble expansion rate. The resulting constraints provide new information on sign-changeable interactions, its equivalences and compatibility with previous models and novel late time universe dynamics.

We investigate models of interacting dark matter and dark energy for the\nuniverse in a spatially flat Friedmann-Robertson-Walker (FRW) space-time. We\nfind the "source equation" for the total energy density and determine the\nenergy density of each dark component. We introduce an effective one-fluid\ndescription to evidence that interacting and unified models are related with\neach other, analyze the effective model and obtain the attractor solutions. We\nstudy linear and nonlinear interactions, the former comprises a linear\ncombination of the dark matter and dark energy densities, their first\nderivatives, the total energy density, its first and second derivatives and a\nfunction of the scale factor. The latter is a possible generalization of the\nlinear interaction consisting of an aggregate of the above linear combination\nand a significant nonlinear term built with a rational function of the dark\nmatter and dark energy densities homogeneous of degree one. We solve the\nevolution equations of the dark components for both interactions and examine\nexhaustively several examples. There exist cases where the effective one-fluid\ndescription produces different alternatives to the $\\La$CDM model and cases\nwhere the problem of coincidence is alleviated. In addition, we find that some\nnonlinear interactions yield an effective one-fluid model with a Chaplygin gas\nequation of state, whereas others generate cosmological models with de Sitter\nand power-law expansions. We show that a generic nonlinear interaction induces\nan effective equation of state which depends on the scale factor in the same\nway that the variable modified Chaplygin gas model, giving rise to the "relaxed\nChaplygin gas model".\n

We have presented FRW cosmological model in the framework of Brans-Dicke theory. This paper deals with a new proposed form of deceleration parameter and cosmological constant Λ. The effect of bulk viscosity is also studied in the presence of modified Chaplygin gas equation of state (p=Aρ-B/ρn). Furthermore, we have discussed the physical behaviours of the models.

Brane inflationary universe model in the context of a Chaplygin gas equation of state is studied. General conditions for this model to be realizable are discussed. In the high-energy limit and by using a chaotic potential we describe in great details the characteristic of this model. The parameters of the model are restricted by using recent astronomical observations.

We study holographic complexity for the rotating quantum BTZ black holes (quBTZ), the BTZ black holes with corrections from bulk quantum fields. Using double holography, the combined system of backreacted rotating BTZ black holes with conformal matters, can be holographically described by the rotating AdS4 C-metric with the BTZ black hole living on a codimension-1 brane. We investigate both volume complexity and action complexity of rotating quBTZ, and pay special attention to their late-time behaviors. When the mass of BTZ black hole is not very small compared to geff2/3/G3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {g}_{\ extrm{eff}}^{2/3}/{G}_3 $$\\end{document} and the rotation is not very slow compared to parameter ℓ, where geff as well as ℓ both characterize the backreaction of quantum fields and G3 is the 3D Newton constant, we show that the late-time rates of the volume complexity and the action complexity agree with each other up to a factor 2 and reduce to the ones of BTZ at the leading classical order, and they both receive subleading quantum corrections. For the volume complexity, the leading quantum correction comes from the backreaction of conformal matter on the geometry, similar to the static quBTZ case. For the action complexity, unlike the static case, the Wheeler-de Witt (WdW) patch in computing the action complexity for the rotating black hole does not touch the black hole singularity such that the leading order result is in good match with the one of classical BTZ. However, when the mass of BTZ black hole is small compared to geff2/3/G3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {g}_{\ extrm{eff}}^{2/3}/{G}_3 $$\\end{document} or the rotation parameter a is small compared to ℓ, the quantum correction to the action complexity could be significant such that the late-time slope of the action complexity of quBTZ deviates very much from the one of classical BTZ. Remarkably, we notice that the nonrotating limit a → 0 is singular and the action complexity of the static quBTZ black holes cannot be reproduced by taking the nonrotating limit a → 0 on the one of the rotating black holes. This discontinuity also appears in higher dimensional rotating black holes, such as Kerr-AdS4 black hole and rotating AdS5 black hole.

In this work, we present a study to probe the nature of interactions between black hole microstructures for the case of the BTZ black holes. Even though BTZ black holes without any angular momentum or electric charge thermodynamically behave as an ideal gas, i.e. with non-interacting microstructures; in the presence of electric charge or angular momentum, BTZ black holes are associated with repulsive interactions among the microstructures. We extend the study to the case of exotic BTZ black holes with mass $M = \alpha m + \gamma \frac{j}{l}$ and angular momentum $J=\alpha j + \gamma l m$, for arbitrary values of $ (\alpha, \gamma)$ ranging from purely exotic $(\alpha=0,\gamma=1)$, slightly exotic $(\alpha > \frac{1}{2},\gamma < \frac{1}{2})$ and highly exotic $(\alpha < \frac{1}{2}, \gamma > \frac{1}{2})$. We find that unlike the normal BTZ black holes (the case $\alpha =1,\gamma =0$), there exist both attraction as well as repulsion dominated regions in all the cases of exotic BTZ black holes.

Recently, the theory of topologically massive gravity non-minimally coupled to a scalar field has been proposed, which comes from the Lorentz–Chern–Simons theory (JHEP 06, 113, 2015), a torsion-free theory. We extend this theory by adding an extra term which makes the torsion to be non-zero. We show that the BTZ spacetime is a particular solution to this theory in the case where the scalar field is constant. The quasi-local conserved charge is defined by the concept of the generalized off-shell ADT current. Also a general formula is found for the entropy of the stationary black hole solution in context of the considered theory. The obtained formulas are applied to the BTZ black hole solution in order to obtain the energy, the angular momentum and the entropy of this solution. The central extension term, the central charges and the eigenvalues of the Virasoro algebra generators for the BTZ black hole solution are thus obtained. The energy and the angular momentum of the BTZ black hole using the eigenvalues of the Virasoro algebra generators are calculated. Also, using the Cardy formula, the entropy of the BTZ black hole is found. It is found that the results obtained in two different ways exactly match, just as expected.

In this paper, the charged thin-shell wormholes have been constructed by using cut-and-paste approach in the framework of [Formula: see text] theory of gravity. The stability analysis is performed in [Formula: see text] gravity formalism, where [Formula: see text] and [Formula: see text] are nonzero constants, with a linear equation of state. The stable and unstable regions have been examined for different values of the parameters involved in the model. The effect of charge and mass on the throat radius is analyzed and stability of thin shell is obtained.

The weak cosmic censorship conjecture in the near-extremal BTZ black hole has been tested using test particles and fields. It has been claimed that such a black hole can be overspun. In this paper, we review the thermodynamics and weak cosmic censorship conjecture in BTZ black holes using the scattering of a scalar field. The first law of thermodynamics in the non-extremal BTZ black hole is recovered. For the extremal and near-extremal black holes, due to the divergence of the variation of entropy, we test the weak cosmic censorship conjecture by evaluating the minimum of the function f, and find that both the extremal and near-extremal black holes cannot be overspun.