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We study the late-time cosmological tensions using the low-redshift background and redshift-space distortion data by employing a machine learning (ML) technique. By comparing the generated observables with the standard cosmological…

Cosmology and Nongalactic Astrophysics · Physics 2023-10-26 Mayukh R. Gangopadhyay , M. Sami , Mohit K. Sharma

Dynamical dark energy (DE) has been proposed to explain various aspects of the cosmological constant (CC) problem(s). For example, it is very difficult to accept that a strictly constant Lambda-term constitutes the ultimate explanation for…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Javier Grande , Joan Sola , Hrvoje Stefancic

We assume the cosmological dark sector to consist of pressureless matter and holographic dark energy with a cutoff length proportional to the Ricci scale. The requirement of separate energy-momentum conservation of the components is shown…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-15 Sergio del Campo , Júlio. C. Fabris , Ramón Herrera , Winfried Zimdahl

Measurements of the current expansion rate of the Universe, $H_0$, using standard candles, disagree with those derived from observations of the Cosmic Microwave Background (CMB). This discrepancy, known as the Hubble tension, is substantial…

Cosmology and Nongalactic Astrophysics · Physics 2024-02-05 Sergio Torres-Arzayus

The standard cosmological model currently in force, aka $\Lambda$CDM, has been plagued with a variety of tensions in the last decade or so, which puts it against the wall. At the core of the $\Lambda$CDM we have a rigid cosmological term,…

Cosmology and Nongalactic Astrophysics · Physics 2025-03-19 Adria Gómez-Valent , Joan Solà Peracaula

In string gas cosmology, extra dimensions are stabilised by a gas of strings. In the matter-dominated era, competition between matter pushing the extra dimensions to expand and the string gas pulling them back can lead to oscillations of…

High Energy Physics - Theory · Physics 2009-04-17 Francesc Ferrer , Tuomas Multamaki , Syksy Rasanen

A six-dimensional universe with two branes in the "football-shaped" geometry leads to an almost realistic cosmology. We describe a family of exact solutions with time dependent characteristic size of internal space. After a short…

High Energy Physics - Theory · Physics 2010-04-05 Jan-Markus Schwindt , Christof Wetterich

We investigate the model of dark matter-dark energy (DM-DE) interaction with coupling strength proportional to the multiplication of dark sector densities with different power indices $Q = \gamma \rho_{\rm c}^{\alpha} \rho_{\rm d}^{\beta}$.…

Cosmology and Nongalactic Astrophysics · Physics 2020-08-26 Gong Cheng , Yin-Zhe Ma , Fengquan Wu , Jiajun Zhang , Xuelei Chen

We investigate the possibility of a dark energy universe emerging from an action with higher-order string loop corrections to Einstein gravity in the presence of a massless dilaton. These curvature corrections (up to $R^4$ order) are…

High Energy Physics - Theory · Physics 2008-11-26 E. Elizalde , S. Jhingan , S. Nojiri , S. D. Odintsov , M. Sami , I. Thongkool

Cosmological consequences of a string-motivated dark energy scenario featuring a scalar field coupled to the Gauss-Bonnet invariant are investigated. We study the evolution of the universe in such a model, identifying its key properties.…

Astrophysics · Physics 2008-11-26 Tomi Koivisto , David F. Mota

In this Letter, we study the implications of string Swampland criteria for dark energy in view of ongoing and future cosmological observations. If string theory should be the ultimate quantum gravity theory, there is evidence that exact de…

Cosmology and Nongalactic Astrophysics · Physics 2018-12-12 Lavinia Heisenberg , Matthias Bartelmann , Robert Brandenberger , Alexandre Refregier

In this work, we studied four types of cosmological models with different mechanisms driving the accelerated expansion of the universe, include Braneworld models, Chaplygin Gas models, Emergent Dark Energy models, and cosmological torsion…

Cosmology and Nongalactic Astrophysics · Physics 2024-05-02 Ziqiang Liu , Tonghua Liu , Xinyi Zhong , Yifei Xu , Xiaogang Zheng

We consider the cosmology of a thick codimension 1 brane. We obtain the matching conditions leading to the cosmological evolution equations and show that when one includes matter with a pressure component along the extra dimension in the…

High Energy Physics - Theory · Physics 2009-11-11 Ignacio Navarro , Jose Santiago

A string field theory(SFT) nonlocal model of the cosmological dark energy providing w<-1 is briefly surveyed. We summarize recent developments and open problems, as well as point out some theoretical issues related with others applications…

High Energy Physics - Theory · Physics 2008-11-26 Irina Ya. Aref'eva

We apply a new non-parametric Bayesian method for reconstructing the evolution history of the equation-of-state $w$ of dark energy, based on applying a correlated prior for $w(z)$, to a collection of cosmological data. We combine the latest…

Cosmology and Nongalactic Astrophysics · Physics 2013-03-20 Gong-Bo Zhao , Robert G. Crittenden , Levon Pogosian , Xinmin Zhang

The big bang quantum cosmology model introduces the trace $J$ of the Schouten tensor as a form of dynamic dark energy. Together with cold dark matter, these components form the so-called $J$CDM cosmology model, proposed by M.H.P.M. van…

Cosmology and Nongalactic Astrophysics · Physics 2026-04-07 Yicheng Wang , Yupeng Yang , Xinyi Dai , Shuangxi Yi , Yankun Qu , Fayin Wang

We use the Simon, Verde, & Jimenez (2005) determination of the redshift dependence of the Hubble parameter to constrain cosmological parameters in three dark energy cosmological models. We consider the standard $\Lambda$CDM model, the XCDM…

Astrophysics · Physics 2011-02-11 Lado Samushia , Bharat Ratra

We present a new set of analytic solutions of general relativity with a negative cosmological constant, which describe black strings and black p-branes in arbitrary number of dimensions, $D$. The solutions are supported by minimally…

High Energy Physics - Theory · Physics 2018-02-14 Adolfo Cisterna , Julio Oliva

Observing dark energy dynamics is the most important aspect of the dark energy research. In this paper we perform an analysis of the constraints on the property of dark energy from the current astronomical observations. We pay particular…

Astrophysics · Physics 2009-11-13 Jun-Qing Xia , Gong-Bo Zhao , Bo Feng , Hong Li , Xinmin Zhang

We use angular size versus redshift data for galaxy clusters from Bonamente et al. (2006) to place constraints on model parameters of constant and time-evolving dark energy cosmological models. These constraints are compatible with those…

Cosmology and Nongalactic Astrophysics · Physics 2013-07-12 Yun Chen , Bharat Ratra
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