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We investigate the virialization of cosmic structures in the framework of flat FLRW cosmological models, in which the vacuum energy density evolves with time. In particular, our analysis focuses on the study of spherical matter…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-21 S. Basilakos , M. Plionis , J. Sola

We present the nonlinear growth of bound cosmological structures using the spherical collapse approach in the shift-symmetric Galileon theories. In particular, we focus on the class of models belonging to the Kinetic Gravity Braiding by…

Cosmology and Nongalactic Astrophysics · Physics 2024-01-09 Inês S. Albuquerque , Noemi Frusciante , Francesco Pace , Carlo Schimd

We use 1-dimensional numerical simulations to study spherical collapse in the f(R) gravity models. We include the nonlinear coupling of the gravitational potential to the scalar field in the theory and use a relaxation scheme to follow the…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-27 Alex Borisov , Bhuvnesh Jain , Pengjie Zhang

Using the classical top-hat profile, we study the non-linear growth of spherically symmetric density perturbation and structure formation in $f(T)$ gravities. In particular, three concrete models, which have been tested against the…

General Relativity and Quantum Cosmology · Physics 2017-03-24 Rui-hui Lin , Xiang-hua Zhai , Xin-zhou Li

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

Employing the spherical collapse (SC) formalism, we investigate the linear evolution of the matter over-density for energy-momentum-squared gravity (EMSG), which in practical phenomenological terms, one may imagine as an extension of the…

Cosmology and Nongalactic Astrophysics · Physics 2023-07-26 Bita Farsi , Ahmad Sheykhi , Mohsen Khodadi

We study the gravitational clustering of spherically symmetric overdensities and the statistics of the resulting dark matter halos in the "symmetron model", in which a new long range force is mediated by a $Z_2$ symmetric scalar field.…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-17 Laura Taddei , Riccardo Catena , Massimo Pietroni

We study the spherical collapse model in the presence of external gravitational tidal shear fields for different dark energy scenarios and investigate the impact on the mass function and cluster number counts. While previous studies of the…

Cosmology and Nongalactic Astrophysics · Physics 2016-12-12 Robert Reischke , Francesco Pace , Sven Meyer , Björn Malte Schäfer

We study structure formation in a phenomenological model of modified gravity which interpolates between LambdaCDM and phenomenological DGP-gravity. Generalisation of spherical collapse by using the Birkhoff-theorem along with the modified…

Astrophysics · Physics 2013-03-07 Bjoern Malte Schaefer , Kazuya Koyama

We use the spherical collapse model to demonstrate that the observable average density of virialized clusters depends on the properties of dark energy along with the properties of gravity on cluster scales and can therefore be used as a…

Cosmology and Nongalactic Astrophysics · Physics 2023-08-23 Evangelos A. Paraskevas , Leandros Perivolaropoulos

We refine the mass and environment dependent spherical collapse model of chameleon $f(R)$ gravity by calibrating a phenomenological correction inspired by the parameterized post-Friedmann framework against high-resolution $N$-body…

Cosmology and Nongalactic Astrophysics · Physics 2017-04-12 Matteo Cataneo , David Rapetti , Lucas Lombriser , Baojiu Li

As one of the most powerful probes of cosmological structure formation, the abundance of massive galaxy clusters is a sensitive probe of modifications to gravity on cosmological scales. In this paper, we present results from N-body…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-17 Simone Ferraro , Fabian Schmidt , Wayne Hu

In this work we investigate the spherical collapse model in flat FRW dark energy universes. We consider the Holographic Dark Energy (HDE) model as a dynamical dark energy scenario with a slowly time-varying equation-of-state (EoS) parameter…

General Relativity and Quantum Cosmology · Physics 2015-01-27 Tayebe Naderi , Mohammad Malekjani , Francesco Pace

In the framework of the spherical collapse model we study the influence of shear and rotation terms for dark matter fluid in clustering dark energy models. We evaluate, for different equations of state, the effects of these terms on the…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-19 F. Pace , R. C. Batista , A. Del Popolo

In this work we study the growth of cold dark matter density perturbations in the nonlinear regime on a conformally coupled quintessence model in which the background is designed to mimic a $\Lambda$CDM cosmology. The spherical collapse of…

Cosmology and Nongalactic Astrophysics · Physics 2020-01-03 Bruno J. Barros , Tiago Barreiro , Nelson J. Nunes

Under the commonly used spherical collapse model, we study how dark energy affects the growth of large scale structures of the Universe in the context of agegraphic dark energy models. The dynamics of the spherical collapse of dark matter…

General Relativity and Quantum Cosmology · Physics 2017-10-11 M. Rezaei , M. Malekjani

We compute the critical density of collapse for spherically symmetric overdensities in a class of f(R) modified gravity models. For the first time we evolve the Einstein, scalar field and non-linear fluid equations, making the minimal…

Cosmology and Nongalactic Astrophysics · Physics 2013-11-26 Michael Kopp , Stephen A. Appleby , Ixandra Achitouv , Jochen Weller

We study the virialization of the cosmic structures in the framework of flat cosmological models where the dark energy component plays an important role in the global dynamics of the universe. In particular, our analysis focuses on the…

Astrophysics · Physics 2008-11-26 Spyros Basilakos , Nikos Voglis

We generalize the small scale dynamics of the universe by taking into account models with an equation of state which evolves with time, and provide a complete formulation of the cluster virialization attempting to address the nonlinear…

Cosmology and Nongalactic Astrophysics · Physics 2009-09-01 S. Basilakos , J. C. Bueno Sanchez , Leandros Perivolaropoulos

We study the gravitational collapse of an overdensity of nonrelativistic matter under the action of gravity and a chameleon scalar field. We show that the spherical collapse model is modified by the presence of a chameleon field. In…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-17 Ph. Brax , R. Rosenfeld , D. A. Steer
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