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An alternative to the postulate of dark energy required to explain the accelerated expansion of the universe is to adopt an inhomogeneous cosmological model to explain the supernovae data without dark energy. We adopt a void cosmology…

Cosmology and Nongalactic Astrophysics · Physics 2016-08-02 J. W. Moffat

We discuss cosmological inference from galaxy surveys, the X-Ray Background (XRB) and the Cosmic Microwave Background (CMB). We assume a family of Cold Dark Matter (CDM) models in a spatially flat universe with an initially scale-invariant…

Astrophysics · Physics 2007-05-23 Ofer Lahav , Sarah L. Bridle

The standard model of the universe, $\lambda$CDM, is based on the Friedmann-Lema\^itre-Robertson-Walker metric with a flat three-dimensional coordinate space and the Friedmann equations~\cite{ParticleDataGroup:2024cfk}. The cosmological…

High Energy Physics - Phenomenology · Physics 2025-11-24 M. M. Musakhanov

A Friedmann--Robertson--Walker Universe is studied with a dark energy component represented by a quintessence field. The Lagrangian for this system, hereafter called the Friedmann--Robertson--Walker--quintessence (FRWq) system, is…

General Relativity and Quantum Cosmology · Physics 2017-08-23 Sergio A. Hojman , Felipe A. Asenjo , Carlos A. Rubio

The common nature of dark matter and dark energy is argued in [1] based on the approach that the cosmological constant \Lambda enters the weak-field General Relativity following from Newton theorem on the "sphere-point mass" equivalency…

General Physics · Physics 2019-02-27 V. G. Gurzadyan , A. Stepanian

In this work it is investigated the evolution of a Universe where a scalar field, non-minimally coupled to space-time curvature, plays the role of quintessence and drives the Universe to a present accelerated expansion. A non-relativistic…

General Relativity and Quantum Cosmology · Physics 2009-11-11 J. B. Binder , G. M. Kremer

The two fundamental assumptions in cosmology are that the Universe is statistically homogeneous and isotropic when averaged on large scales. Given the big implication of these assumptions, there has been a lot of statistical tests carried…

Cosmology and Nongalactic Astrophysics · Physics 2014-09-04 Yabebal Fantaye

The standard model of cosmology, {\Lambda}CDM, is the simplest model that matches the current observations, but it relies on two hypothetical components, to wit, dark matter and dark energy. Future galaxy surveys and cosmic microwave…

Cosmology and Nongalactic Astrophysics · Physics 2018-08-13 Cyrille Doux , Mariana Penna-Lima , Sandro D. P. Vitenti , Julien Tréguer , Eric Aubourg , Ken Ganga

We propose a new class of quintessence models in which late times oscillations of a scalar field give rise to an effective equation of state which can be negative and hence drive the observed acceleration of the universe. Our ansatz…

Astrophysics · Physics 2009-10-31 Varun Sahni , Limin Wang

We introduce the $dipole$ $cosmological$ $principle$, the idea that the Universe is a maximally Copernican cosmology, compatible with a cosmic flow. It serves as the most symmetric paradigm that generalizes the FLRW ansatz, in light of the…

Cosmology and Nongalactic Astrophysics · Physics 2023-07-17 Chethan Krishnan , Ranjini Mondol , M. M. Sheikh-Jabbari

We show that a scalar and a fermion charged under a global U(1) symmetry can not only explain the existence and abundance of dark matter (DM) and dark radiation (DR), but also imbue DM with improved scattering properties at galactic scales,…

High Energy Physics - Phenomenology · Physics 2014-10-21 Xiaoyong Chu , Basudeb Dasgupta

From an observational perspective cosmology is today in excellent shape - advances in instrumentation and data processing have enabled us to study the universe in detail back to when the first galaxies formed, map the fluctuations in the…

High Energy Physics - Phenomenology · Physics 2007-05-23 Subir Sarkar

The phenomenology of the modified Newtonian dynamics (MOND) can be recovered from a mechanism of "gravitational polarization" of some dipolar medium playing the role of dark matter. We review a relativistic model of dipolar dark matter…

Cosmology and Nongalactic Astrophysics · Physics 2013-12-30 Luc Blanchet , David Langlois , Alexandre Le Tiec , Sylvain Marsat

The first comprehensive analyses of Planck data reveal that the cosmological model with dark energy and cold dark matter can satisfactorily explain the essential physical features of the expanding Universe. However, the inability to…

General Physics · Physics 2014-05-15 Davor Palle

We study the evolution of the universe in the presence of inflaton, matter, radiation, and holographic dark energy. The time evolution of the scale factor is obtained by solving the Friedmann equation of the universe with a good…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Hyeong-Chan Kim , Jae-Weon Lee , Jungjai Lee

Disformally coupled cosmologies arise from Dirac-Born-Infeld actions in Type II string theories, when matter resides on a moving hidden sector D-brane. Since such matter interacts only very weakly with the standard model particles, this…

High Energy Physics - Theory · Physics 2015-06-18 Tomi Koivisto , Danielle Wills , Ivonne Zavala

A recently proposed Dynamical Space-time Cosmology (DSC) that unifies dark energy and dark matter is studied. The general action of this scenario includes a Lagrange multiplier, which is coupled to the energy momentum tensor and a scalar…

General Relativity and Quantum Cosmology · Physics 2019-06-10 Fotios K. Anagnostopoulos , David Benisty , Spyros Basilakos , Eduardo I. Guendelman

We propose a simple scenario which explains the observed matter-antimatter imbalance and the origin of dark matter in the Universe. We use the Einstein-Cartan-Sciama-Kibble theory of gravity which naturally extends general relativity to…

General Relativity and Quantum Cosmology · Physics 2011-06-30 Nikodem J. Poplawski

We present new fast numerical simulations of cosmic microwave background and large scale structure in the case in which the cosmological dark matter is made entirely or partly of mirror matter. We consider scalar adiabatic primordial…

Cosmology and Nongalactic Astrophysics · Physics 2014-01-24 Paolo Ciarcelluti , Quentin Wallemacq

The original Dirac Equation is modified in the simplest imaginable and most trivial manner to include a universal 4-Vector Cosmological Field term in the space and time dimensions. This cosmological field leads to a modified Dirac Equation…

General Physics · Physics 2009-05-05 G. G. Nyambuya
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