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Related papers: Gravitational entropies in LTB dust models

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The approximate homogeneity of spatial sections of the Universe is well supported observationally, but the inhomogeneity of the spatial sections is even better supported. Here, we consider the implications of inhomogeneity in dust models…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-20 Boudewijn F. Roukema , Vincent Blanloeil , Jan J. Ostrowski

We examine in this paper the possibility of finding exact solutions for Teleparallel Gravity (TG) of the type of spherically symmetric Lema\^\i tre-Tolman-Bondi (LTB) dust models. We apply to the LTB metric, as obtained from the…

General Relativity and Quantum Cosmology · Physics 2021-06-07 Sebastián Nájera , Aram Aguilar , Celia Escamilla-Rivera , Roberto A. Sussman

Bulk viscous cosmological models is presented in the teleparallel ($F(T)$, where $T$ denotes torsion) gravity. In the teleparallel gravity, the Lagrangian of the gravitational action contains a general function $F(T)= T+ f(T)=(1+ \gamma)…

General Relativity and Quantum Cosmology · Physics 2025-07-22 Partha Sarathi Debnath , Chanchal Mondal , B. C. Paul

Asymptotically AdS rotating black holes for the Bergshoeff-Hohm-Townsend (BHT) massive gravity theory in three dimensions are considered. In the special case when the theory admits a unique maximally symmetric solution, apart from the mass…

High Energy Physics - Theory · Physics 2010-03-25 Gaston Giribet , Julio Oliva , David Tempo , Ricardo Troncoso

Some models within the framework of Gauss-Bonnet gravities are considered in the presence of a non-minimally coupled scalar field. By imposing a particular constraint on the scalar field coupling, an extension of the called…

General Relativity and Quantum Cosmology · Physics 2022-07-19 Sergei D. Odintsov , Diego Saez-Chillon Gomez , German S. Sharov

The causal entropy bound (CEB) is confronted with recent explicit entropy calculations in weakly and strongly coupled conformal field theories (CFTs) in arbitrary dimension $D$. For CFT's with a large number of fields, $N$, the CEB is found…

High Energy Physics - Theory · Physics 2009-11-07 R. Brustein , S. Foffa , G. Veneziano

We investigate a weak version of subsystem eigenstate thermalization hypothesis (ETH) for a two-dimensional large central charge conformal field theory by comparing the local equivalence of high energy state and thermal state of canonical…

High Energy Physics - Theory · Physics 2017-11-22 Song He , Feng-Li Lin , Jia-ju Zhang

The recently proposed gravitational entropy generalize the usual black hole entropy to Euclidean solutions without U(1) symmetry in the framework of Einstein gravity. The entropy of such smooth configuration is given by the area of minimal…

High Energy Physics - Theory · Physics 2013-08-07 Bin Chen , Jia-ju Zhang

In a thermodynamical model of cosmological FLRW event horizons for the dark energy (DE), we consider a logarithmic corrective term in the entropy to which corresponds a new term in the DE density. This model of $\Lambda (t)$ in an…

Astrophysics · Physics 2016-08-15 Cécile Barbachoux , Jérome Gariel , Gérard Le Denmat

The BFSS matrix model provides an example of gauge-theory / gravity duality where the gauge theory is a model of ordinary quantum mechanics with no spatial subsystems. If there exists a general connection between areas and entropies in this…

High Energy Physics - Theory · Physics 2020-04-15 Tarek Anous , Joanna L. Karczmarek , Eric Mintun , Mark Van Raamsdonk , Benson Way

A piecewise Tolman-Bondi-Lemaitre (TBL) cell-model for the universe incorporating local collapsing and expanding inhomogeneities is presented here. The cell-model is made up of TBL underdense and overdense spherical regions surrounded by an…

General Relativity and Quantum Cosmology · Physics 2009-10-31 A. Chamorro , S. S. Deshingkar , I. H. Dwivedi , P. S. Joshi

Here, we consider new nonadditive entropy of the apparent horizon $S_K=S_{BH}/(1+\gamma S_{BH})$ with $S_{BH}$ being the Bekenstein--Hawking entropy. This is an alternative of the R\'{e}nyi and Tsallis entropies, that allows us, by…

General Physics · Physics 2025-11-18 S. I. Kruglov

Both the Barrow and Tsallis $\delta$ entropies are one-parameter generalizations of the black-hole entropy, with the same microcanonical functional form. The ensuing deformation is quantified by a dimensionless parameter $\Delta$, which in…

General Relativity and Quantum Cosmology · Physics 2024-10-28 Petr Jizba , Gaetano Lambiase , Giuseppe Gaetano Luciano , Leonardo Mastrototaro

In this paper, bulk viscosity is introduced in new holographic dark energy (HDE) to describe the effects of cosmic non-perfect fluid on the evolution of the universe in modified $f(R,T)$ gravity. Assuming $f(R,T)=R+\lambda T$, where $R$ is…

General Relativity and Quantum Cosmology · Physics 2018-04-17 C P Singh , Milan Srivastava

High-precision cosmological observations have revealed persistent tensions within the standard $\Lambda$CDM paradigm, most notably the discrepancy in the Hubble constant and the lower than predicted amplitude of late-time matter clustering…

Cosmology and Nongalactic Astrophysics · Physics 2026-05-28 Biswajit Pandey

In this study, we consider three dark energy models in which $\Lambda$ is not constant, but has a dynamic nature that depends on the Hubble parameter $H$ and/or its time derivative $\dot{H}$. We analyze the generalized running vacuum model,…

Cosmology and Nongalactic Astrophysics · Physics 2022-01-05 Christine R. Farrugia , Joseph Sultana , Jurgen Mifsud

We argue that a $\Lambda$-inflation model can ensure large relative contribution of cosmic gravity waves into the $\Delta T/T$ at COBE scale preserving at the same time a near scale-invariant spectrum of cosmological density perturbations…

Astrophysics · Physics 2009-10-31 Vladimir N. Lukash

We investigate Lema\^itre-Tolman-Bondi (LTB) models, whose early time evolution and bang time are homogeneous and the distance - redshift relation and local Hubble parameter are inherited from the $\Lambda$CDM model. We show that the…

Cosmology and Nongalactic Astrophysics · Physics 2015-12-17 Peter Sundell , Edvard Mörtsell , Iiro Vilja

We present a comparative analysis of the plethora of nonextensive and/or nonadditive entropies which go beyond the standard Boltzmann-Gibbs formulation. After defining the basic notions of additivity, extensivity, and composability, we…

General Relativity and Quantum Cosmology · Physics 2024-09-30 Mariusz P. Dabrowski

We explore the viability of three models in $f(T,B)$ gravity using data from recent surveys based on cosmic chronometers, the Pantheon data set, and baryonic acoustic oscillation data. We also assess the consistency of these models and data…

General Relativity and Quantum Cosmology · Physics 2022-12-23 Rebecca Briffa , Celia Escamilla-Rivera , Jackson Levi Said , Jurgen Mifsud
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