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The $\Lambda$CDM framework offers a remarkably good description of our universe with a very small number of free parameters, which can be determined with high accuracy from currently available data. However, this does not mean that the…

Cosmology and Nongalactic Astrophysics · Physics 2015-07-22 Yves Zolnierowski , Alain Blanchard

We present a tomographic cosmological weak lensing analysis of the HST COSMOS Survey. Applying our lensing-optimized data reduction, principal component interpolation for the ACS PSF, and improved modelling of charge-transfer inefficiency,…

We apply the holographic principle in the cosmological context through the nonadditive Tsallis entropy, used to describe the thermodynamic properties of nonstandard statistical systems such as the gravitational ones. Assuming the future…

General Relativity and Quantum Cosmology · Physics 2019-05-29 Rocco D'Agostino

We explore a generalised unified dark energy model that incorporates a non-minimal interaction between a tachyonic fluid and an additional scalar field. Specifically, we require that the second field possesses a vacuum energy, introducing…

General Relativity and Quantum Cosmology · Physics 2023-08-31 Peter K. S. Dunsby , Orlando Luongo , Marco Muccino

The framed standard model (FSM), constructed to explain the empirical mass and mixing patterns of quarks and leptons, gives the same result as the standard model in almost all areas in particle physics where it has been successfully…

High Energy Physics - Phenomenology · Physics 2023-08-24 Jose Bordes , HM Chan , ST Tsou

It has recently been shown that the observed Hubble function for cosmological expansion can be fitted accurately back to redshift unity (7.33 Gyr ago) with only one free constant, while neglecting cosmic curvature and mass, using the…

General Physics · Physics 2021-05-26 R. K. Nesbet

In this paper, we propose a modified scale factor (MSF) that allows us to explore the accelerating expansion of the universe without invoking the traditional dark-energy model, as described in the Lambda cold dark matter ($\Lambda$CDM)…

Cosmology and Nongalactic Astrophysics · Physics 2024-12-10 Goratamang Gaedie , Shambel Sahlu , Amare Abebe

In view of late-time cosmic acceleration, a dark energy cosmological model is revisited wherein Einstein's cosmological constant is considered as a candidate of dark energy. Exact solution of Einstein field equations (EFEs) is derived in a…

General Relativity and Quantum Cosmology · Physics 2019-11-22 S. K. J. Pacif , Md Salahuddin Khan , L. K. Paikroy , Shalini Singh

Despite the many efforts, our theoretical understanding of the ultimate nature of the dark energy component of the universe still lags well behind the astounding experimental evidence achieved from the increasingly sophisticated…

Cosmology and Nongalactic Astrophysics · Physics 2015-01-19 Adria Gomez-Valent , Joan Sola , Spyros Basilakos

In a previous work it was shown that by considering the quantum nature of the gravitational field mediator, it is possible to introduce the momentum energy of the graviton into the Einstein equations as an effective cosmological constant.…

General Physics · Physics 2022-03-16 Tonatiuh Matos , Luis Osvaldo Tellez-Tovar

It is known that the unregularized expressions for the stress-energy tensor components corresponding to subhorizon and superhorizon vacuum fluctuations of a massless scalar field in a Friedmann-Robertson-Walker background are characterized…

General Relativity and Quantum Cosmology · Physics 2010-11-19 Ali Kaya

Dark energy as a quintessence component causes a typical modification of the background cosmic expansion, which in addition to its clustering properties, can leave a potentially distinctive signature on large scale structures. Many previous…

Cosmology and Nongalactic Astrophysics · Physics 2010-02-04 J. -M. Alimi , A. Fuzfa , V. Boucher , Y. Rasera , J. Courtin , P. -S. Corasaniti

Following the idea of the induced matter theory, for a non-vacuum five-dimensional version of general relativity, we propose a model in which the induced terms emerging from the extra dimension in our four-dimensional space-time, supposed…

General Relativity and Quantum Cosmology · Physics 2018-07-27 Amir F. Bahrehbakhsh

In a previous paper (Ref. [1]) the presence of dark energy in our universe was explained as the fingerprint of a comprehensive, much older and expanding multiverse with positive spatial curvature, whose space-time is spanned by this energy,…

General Relativity and Quantum Cosmology · Physics 2018-09-06 Rebhan Eckhard

Simple models are constructed for "acceleressence" dark energy: the latent heat of a phase transition occurring in a hidden sector governed by the seesaw mass scale v^2/M_Pl, where v is the electroweak scale and M_Pl the gravitational mass…

Astrophysics · Physics 2009-09-29 Z. Chacko , Lawrence J. Hall , Yasunori Nomura

The energy scale of Dark Energy, $\sim 2 \times 10^{-3}$ eV, is a long way off compared to all known fundamental scales - except for the neutrino masses. If Dark Energy is dynamical and couples to neutrinos, this is no longer a coincidence.…

Cosmology and Nongalactic Astrophysics · Physics 2016-03-23 Youness Ayaita , Marco Baldi , Florian Führer , Ewald Puchwein , Christof Wetterich

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 study the spherical collapse of non-top-hat matter fluctuations in the presence of dark energy with arbitrary sound speed. The model is described by a system of partial differential equations solved using a pseudo-spectral method with…

Cosmology and Nongalactic Astrophysics · Physics 2023-02-22 R. C. Batista , H. P. de Oliveira , L. R. W. Abramo

Based on some observations, the apparent energy, associated with gravity, of vacuums is defined, with that of normal vacuums to be zero and that of the vacuums losing some energy to be negative. An important application of the energy is its…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Yi-Ping Qin

We use cosmological perturbation theory to study the backreaction effects of a self-consistent and well-defined cosmological averaging on the dynamics and the evolution of the Universe. Working with a perturbed…

General Relativity and Quantum Cosmology · Physics 2013-10-30 Iain A. Brown , Alan A. Coley , D. Leigh Herman , Joey Latta