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We discuss an interacting tachyonic dark energy model in the context of the holographic principle. The potential of the holographic tachyon field in interaction with dark matter is constructed. The model results are compared with CMB shift…

General Relativity and Quantum Cosmology · Physics 2010-05-25 Sandro M. R. Micheletti

We review recent results on the cosmological models based on the holographic principle which were proposed to explain the most of the problems occurring in the Standard Cosmological Model. It is shown that these models naturally solve the…

Cosmology and Nongalactic Astrophysics · Physics 2015-09-16 Yu. L. Bolotin , O. A. Lemets , D. A. Yerokhin , L. G. Zazunov

Cosmological models involving an interaction between dark matter and dark energy have been proposed in order to solve the so-called coincidence problem. Different forms of coupling have been studied, but there have been claims that…

Different models of the cosmic substratum which pretend to describe the present stage of accelerated expansion of the Universe like the $\Lambda$CDM model or a Chaplygin gas, can be seen as special realizations of a holographic dark energy…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Winfried Zimdahl

We test the theoretical predictions of several cosmological models against different observables to compare the indirect estimates of the current expansion rate of the Universe determined from model fitting with the direct measurements…

Cosmology and Nongalactic Astrophysics · Physics 2016-11-09 Vladimir V. Luković , Rocco D'Agostino , Nicola Vittorio

The Universe's assumed homogeneity and isotropy is known as the cosmological principle. It is one of the assumptions that lead to the Friedmann-Lema\^{\i}tre-Robertson-Walker (FLRW) metric and it is a cornerstone of modern cosmology,…

In this work we investigate the holographic dark energy models with slowly time-varying model parameter defined based on the current Hubble horizon length scale. While the previous studies on the three popular holographic dark energy models…

General Relativity and Quantum Cosmology · Physics 2019-05-07 Mohammad Malekjani , Mehdi Rezaei , Iman A. Akhlaghi

Usually, we assume that there is no inhomogeneity isotropic in terms of our location in our uni- verse. This assumption has not been observationally confirmed yet in sufficient accuracy, and we need to consider the possibility that there…

Cosmology and Nongalactic Astrophysics · Physics 2017-03-06 Hiroyuki Negishi , Ken-ichi Nakao

The Standard Model of cosmology, $\Lambda$CDM, while enormously successful, is currently unable to account for several cosmological anomalies the most prominent of which are in the measurements of the Hubble parameter and $S_8$.…

Cosmology and Nongalactic Astrophysics · Physics 2025-03-14 Amin Aboubrahim , Pran Nath

We present a new generating algorithm to construct exact non static solutions of the Einstein field equations with two-dimensional inhomogeneity. Infinite dimensional families of $G_1$ inhomogeneous solutions with a self interacting scalar…

General Relativity and Quantum Cosmology · Physics 2016-08-15 A. Feinstein , J. Ibáñez , Ruth Lazkoz

Within the standard cosmological model, the presence of Dark Energy (DE) is the only structural difference between the early and late times Universe. While its presence is in full display at late times, it is irrelevant at early times,…

Cosmology and Nongalactic Astrophysics · Physics 2023-09-14 Marco Raveri

New constraints on inhomogeneous Lema\^itre-Tolman-Bondi (LTB) models alternative to Dark Energy are presented, focusing on adiabatic profiles with space-independent Big Bang and baryon fraction. The Baryon Acoustic Oscillation (BAO) scale…

Cosmology and Nongalactic Astrophysics · Physics 2012-10-25 Miguel Zumalacarregui , Juan Garcia-Bellido , Pilar Ruiz-Lapuente

We focus on the class of cosmological models with a time-evolving vacuum energy density of the form $\rho_\Lambda=C_0+C_1 H+C_2 H^2$, where $H$ is the Hubble rate. Higher powers of $H$ could be important for the early inflationary epoch,…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-13 Adria Gomez-Valent , Joan Sola

We study the anisotropic and homogeneous Bianchi type-V Universe with holographic dark energy (HDE) and interacting dark matter (DM). The solution for the field equations have been obtained for a certain form of the deceleration parameter.…

General Relativity and Quantum Cosmology · Physics 2025-07-29 Gunjan Varshney , Anirudh Pradhan , Nasr Ahmed , Vansh Mittal

We derive and analyze a class of spherically symmetric cosmological models whose source is an interactive mixture of inhomogeneous cold dark matter (DM) and a generic homogeneous dark energy (DE) fluid. If the DE fluid corresponds to a…

Astrophysics · Physics 2009-11-10 Roberto A Sussman , Israel Quiros , Osmel Martin Gonzalez

The observed discrepancy of the Hubble parameter measurements in the local universe with the cosmic microwave background (CMB) data may indicate a new physics. It is vital to test the alternative models that reconcile the Hubble tension…

Cosmology and Nongalactic Astrophysics · Physics 2021-09-03 Hossein Moshafi , Shant Baghram , Nima Khosravi

We use strongly gravitationally lensed (SGL) systems to put additional constraints on a set of holographic dark energy models. Data available in the literature (redshift and velocity dispersion) is used to obtain the Einstein radius and…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-17 Victor H. Cardenas , Alexander Bonilla , Veronica Motta , Sergio del Campo

We study a holographic cosmological model in which the infrared cutoff is set by the Ricci's length and dark matter and dark energy do not evolve on their own but interact non-gravitationally with each other. This greatly alleviates the…

Cosmology and Nongalactic Astrophysics · Physics 2011-02-25 Ivan Duran , Diego Pavon

By means of a toy Swiss-cheese cosmological model we will discuss how to set up and carry out in a physically meaningful way the idea of back-reaction, according to which dark energy could be an effective source. We will follow two distinct…

Astrophysics · Physics 2008-05-29 Valerio Marra

The past lightcone of an observer in a cosmological spacetime is the unique geometric structure directly linked to observations. After general properties of the Hawking energy along slices of the past lightcone have previously been studied,…

General Relativity and Quantum Cosmology · Physics 2021-03-29 Dennis Stock