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Modifications to the gravitational potential affect the nonlinear gravitational evolution of large scale structures in the Universe. To illustrate some generic features of such changes, we study the evolution of spherically symmetric…

Astrophysics · Physics 2009-11-06 Matthew C. Martino , Hans F. Stabenau , Ravi K. Sheth

We introduce the N-body simulation technique to follow structure formation in linear and nonlinear regimes for the extended quintessence models (scalar-tensor theories in which the scalar field has a self-interaction potential and behaves…

Cosmology and Nongalactic Astrophysics · Physics 2012-07-04 Baojiu Li , David F. Mota , John D. Barrow

This thesis introduces a set of methods for testing models of modified gravity using galaxy clusters. In particular, a technique for constraining models with a chameleon screening is introduced. In addition, the outlined technique is…

Cosmology and Nongalactic Astrophysics · Physics 2020-11-18 Andrius Tamosiunas

We consider here the dynamics of some homogeneous and isotropic cosmological models with $N$ interacting classical scalar fields non-minimally coupled to the spacetime curvature, as an attempt to generalize some recent results obtained for…

General Relativity and Quantum Cosmology · Physics 2007-05-23 L. Brenig , A. Figueiredo , E. Gunzig , T. M. Rocha Filho , Alberto Saa

In the work's considered density of vacuum energy and dynamic of scalar field in multidimensional theory with cosmological constant. Using method of N.N.Bogolubov coefficients, was gotten expression for influence of anisotropic metric to…

General Physics · Physics 2012-03-05 Sergey Yakovlev

Model of Expansive Nondecelerative Universe (ENU) due to involving Vaidya metric makes it possible to localize the energy density of gravitational field. This its capability allows for answering several open questions and supporting (or…

General Physics · Physics 2007-05-23 Miroslav Sukenik , Jozef Sima

Cosmological $N$-body simulations are the standard tool to study the emergence of the observed large-scale structure of the Universe. Such simulations usually solve for the gravitational dynamics of matter within the Newtonian…

Cosmology and Nongalactic Astrophysics · Physics 2016-11-24 Jacob Brandbyge , Cornelius Rampf , Thomas Tram , Florent Leclercq , Christian Fidler , Steen Hannestad

We present the results of a set of cosmological N-body simulations with standard $\Lambda$CDM cosmology but characterized by a scale-dependent primordial non-Gaussianity of the local type featuring a power-law dependence of the $f_{\rm…

We search for viable f(R) theories of gravity, making use of the equivalence between such theories and scalar-tensor gravity. We find that models can be made consistent with solar system constraints either by giving the scalar a high mass…

Astrophysics · Physics 2008-11-26 Thomas Faulkner , Max Tegmark , Emory F. Bunn , Yi Mao

We study the variation of the gravitational Newton's constant on cosmological scales in scalar-tensor theories of gravity. We focus on the simplest models of scalar-tensor theories with a coupling to the Ricci scalar of the form $F(\sigma)…

Cosmology and Nongalactic Astrophysics · Physics 2022-06-15 Mario Ballardini , Fabio Finelli , Domenico Sapone

The formation of cosmic structures is an important diagnostic for both the dynamics of the cosmological model and the underlying theory of gravity. At the linear level of these structures, certain degeneracies remain between different…

Cosmology and Nongalactic Astrophysics · Physics 2019-08-02 Lavinia Heisenberg , Matthias Bartelmann

This is an essay sketching the line of thinking which has led the present author to propose the constituent or atomic model of gravitation more than a decade ago. It turns out that viewing the problem of gravitation as a quantum many body…

Astrophysics · Physics 2009-10-19 Pawel O. Mazur

We study the large-scale structure formation in the Universe in the frame of scalar-tensor theories as an alternative to general relativity. We review briefly the Newtonian limit of non-minimally coupled scalar-tensor theories and the…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 M. A. Rodriguez-Meza

Initial conditions for (Newtonian) cosmological N-body simulations are usually set by re-scaling the present-day power spectrum obtained from linear (relativistic) Boltzmann codes to the desired initial redshift of the simulation. This…

Cosmology and Nongalactic Astrophysics · Physics 2017-06-28 Christian Fidler , Thomas Tram , Cornelius Rampf , Robert Crittenden , Kazuya Koyama , David Wands

Understanding the structure of the matter distribution in the Universe due to the action of the gravitational instability -- the cosmic web -- is complicated by lack of direct analytic access to the nonlinear domain of structure formation.…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-03 Sergei Shandarin , Salman Habib , Katrin Heitmann

We investigate the possibility of generating initial conditions for cosmological N-body simulations by simulating a system whose correlations at thermal equilibrium approximate well those of cosmological density perturbations. The system is…

Astrophysics · Physics 2009-11-10 M. Joyce , D. Levesque , B. Marcos

The cosmological tests are tight enough now to show that the Friedmann-Lemaitre Lambda CDM cosmological model almost certainly is a useful approximation. This means general relativity theory passes significant tests of the extrapolation of…

Astrophysics · Physics 2017-08-23 P. J. E. Peebles

The work shows that the associated Einstein like gravity for the Klein-Gordon field shows the spontaneous emergence of the cosmological pressure tensor density (CPTD) that in the classical limit leads to the cosmological constant (CC). Even…

General Physics · Physics 2020-07-07 Piero Chiarelli

In this work, we apply the formalism of dynamical systems to analyze the viability of the $\Lambda$CDM model in a generalized form of the hybrid metric-Palatini gravity theory written in terms of its dynamically equivalent scalar-tensor…

General Relativity and Quantum Cosmology · Physics 2024-09-06 João Luís Rosa

The one-loop effective action for non-minimal scalar modified gravity on de Sitter background with a constant scalar field is found. The corresponding induced cosmological constant is evaluated. It is shown that quantum effects in…

General Relativity and Quantum Cosmology · Physics 2011-04-07 G. Cognola , E. Elizalde , S. Nojiri , S. D. Odintsov