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Recent cosmological observations show hints for possible deviations from the standard $\Lambda$CDM paradigm at late times. To study such deviation, we introduce a minimal phenomenological framework in which the total equation of state of…

Cosmology and Nongalactic Astrophysics · Physics 2026-03-18 Shibendu Gupta Choudhury , Anjan A Sen

The $\Lambda$-CDM model of cosmology has done much to clarify our picture of the early universe. However, there are still some questions that $\Lambda$-CDM does not necessarily answer; questions such as what is the fundamental nature of…

Cosmology and Nongalactic Astrophysics · Physics 2024-06-17 Wenzer Qin

Assuming a spatially flat universe, we study the cosmological viability of an infrared corrected teleparallel gravity model, which accounts for late acceleration by weakening gravity at later times on cosmological distances. The theory does…

Cosmology and Nongalactic Astrophysics · Physics 2023-01-11 Mahmoud Hashim , Waleed El Hanafy , Alexey Golovnev , Amr A. El-Zant

We consider multidimensional cosmologies in even-dimensional space-times (D=2n) containg perfect fluid and a multidimensional generalization of the Maxwell field, preserving its conformal invariance (the F field, an n-form). Among models…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Kirill A. Bronnikov

Considering the Friedmann--Lema\^{i}tre--Robertson--Walker (FLRW) metric and the Einstein scalar field system as an underlying gravitational model to construct fractional cosmological models has interesting implications in both classical…

General Relativity and Quantum Cosmology · Physics 2024-07-26 S. M. M. Rasouli , S. Cheraghchi , P. V. Moniz

Modern cosmology is based on the cosmological principle, which states that the Universe is statistically homogeneous and isotropic. When applied in its strict -- rather than statistical -- sense, the cosmological principle leads to the…

Cosmology and Nongalactic Astrophysics · Physics 2025-09-03 Pierre Fleury

We present a joint cosmological analysis combining data from the Planck satellite, the Atacama Cosmology Telescope, and the South Pole Telescope. We construct a unified likelihood that reproduces the measured temperature and polarisation…

Cosmology and Nongalactic Astrophysics · Physics 2026-04-24 M. Tristram , M. Douspis , A. Gorce , S. Henrot-Versillé , L. T. Hergt , S. Ilic , L. McBride , M. Muñoz-Echeverría , E. Pointecouteau , L. Salvati

The recent measurements of the Hubble constant based on the standard $\Lambda$CDM cosmology reveal an underlying disagreement between the early-Universe estimates and the late-time measurements. Moreover, as these measurements improve, the…

General Physics · Physics 2020-11-25 Ram Gopal Vishwakarma

Hydrodynamical simulations of galaxy formation in spatially flat Cold Dark Matter (CDM) cosmologies with and without a cosmological constant (Lambda) are described. A simple star formation algorithm is employed and radiative cooling is…

Astrophysics · Physics 2009-10-31 Vincent Eke , George Efstathiou , Lisa Wright

A cosmological model describing the evolution of $n$ Einstein spaces $(n>1)$ with $m$-component perfect-fluid matter is considered. When all spaces are Ricci-flat and for any $\alpha$-th component the pressures in all spaces are…

General Relativity and Quantum Cosmology · Physics 2011-04-20 V. D. Ivashchuk , V. N. Melnikov

We investigate cosmological solutions of the chameleon model with a non-minimal coupling between the matter and the scalar field through a conformal factor with gravitational strength. By considering the spatially flat FLRW metric and the…

General Relativity and Quantum Cosmology · Physics 2023-11-01 Raziyeh Zaregonbadi , Nasim Saba , Mehrdad Farhoudi

Several isotropic, homogeneous cosmological models containing a self-interacting minimally coupled scalar field, a perfect fluid source and cosmological constant are solved. New exact, asymptotically stable solutions with an inflationary…

General Relativity and Quantum Cosmology · Physics 2009-10-28 Luis P. Chimento , Alejandro S. Jakubi

We propose a minimal extension of the Newtonian action by introducing a time-dependent fractional kernel characterized by a single deformation parameter $\alpha$. This kernel admits a natural interpretation as a nontrivial temporal…

General Relativity and Quantum Cosmology · Physics 2026-04-06 S. M. M. Rasouli

In this first paper we discuss the linear theory and the background evolution of a new class of models we dub SCDEW: Strongly Coupled DE, plus WDM. In these models, WDM dominates today's matter density; like baryons, WDM is uncoupled. Dark…

Cosmology and Nongalactic Astrophysics · Physics 2015-10-09 Silvio A. Bonometto , Roberto Mainini , Andrea V. Macciò

We consider the asymmetric branes model of modified gravity, which can produce late time acceleration of the universe and compare the cosmology of this model to the standard $\Lambda$CDM model and to the DGP braneworld model. We show how…

Cosmology and Nongalactic Astrophysics · Physics 2010-09-13 Eimear O'Callaghan , Ruth Gregory , Alkistis Pourtsidou

The cosmological reconstruction scheme for modified $F(R)$ gravity is developed in terms of e-folding (or, redshift). It is demonstrated how any FRW cosmology may emerge from specific $F(R)$ theory. The specific examples of well-known…

High Energy Physics - Theory · Physics 2014-11-20 Shin'ichi Nojiri , Sergei D. Odintsov , Diego Saez-Gomez

We use a dynamical systems approach based on the method of orthonormal frames to study the dynamics of a two-fluid, non-tilted Bianchi Type I cosmological model. In our model, one of the fluids is a fluid with bulk viscosity, while the…

General Relativity and Quantum Cosmology · Physics 2015-10-22 Ikjyot Singh Kohli , Michael C. Haslam

Instead of assuming a form of gravity and demand cosmology fit with $\Lambda CDM$, a potentially `viable' $f(R)$ gravity model is derived assuming an alternative model of cosmology. Taking the `designer' approach to $f(R)$, a new class of…

General Relativity and Quantum Cosmology · Physics 2018-01-16 Rohin Kumar

The idea of a variable dark energy has been entertained many times in the literature and from many different points of view. Quintessence is just a popular way to implement this idea in recent times, but so far with little success. Another…

Astrophysics · Physics 2007-05-23 Ilya L. Shapiro , Joan Sola

A new class of FLRW cosmological models with time-evolving fundamental parameters should emerge naturally from a description of the expansion of the universe based on the first principles of quantum field theory and string theory. Within…

Cosmology and Nongalactic Astrophysics · Physics 2011-08-09 Javier Grande , Joan Sola , Spyros Basilakos , Manolis Plionis