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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 this work we investigate the spherical collapse model in flat FRW universe containing dark energy component. We consider the Holographic Dark Energy (HDE) model as a dynamical dark energy scenario with slowly time varying EoS parameter…

General Relativity and Quantum Cosmology · Physics 2014-05-27 Tayebe Naderi , Mohammad Malekjani

We study the tachyon scalar field model in flat FRW cosmology with the particular potential $\phi^{-2}$ and the scale factor behavior $a(t)=t^n$. We consider the spherical collapse model and investigate the effects of the tachyon scalar…

General Relativity and Quantum Cosmology · Physics 2017-08-23 M. R. Setare , F. Felegary , F. Darabi

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

There is now strong evidence that the current energy density of the Universe is dominated by dark energy with an equation of state w<-1/3, which is causing accelerated expansion. The build-up of structure within such Universes is subject to…

Astrophysics · Physics 2008-11-26 Will J. Percival

While in the standard cosmological model the accelerated expansion of the Universe is explained by invoking the presence of the cosmological constant term, it is still unclear the true origin of this stunning observational fact. It is…

General Relativity and Quantum Cosmology · Physics 2015-10-07 Mohammad Malekjani , Tayebe Naderi , Francesco Pace

In this paper we study cosmological application of new agegraphic dark energy density in the $f(R)$ gravity framework. We employ the new agegraphic model of dark energy to obtain the equation of state for the new agegraphic energy density…

General Relativity and Quantum Cosmology · Physics 2010-04-30 M. R. Setare

We study the spherical collapse model for several dark energy scenarios using the fully nonlinear differential equation for the evolution of the density contrast within homogeneous spherical overdensities derived from Newtonian…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 F. Pace , J. -C. Waizmann , M. Bartelmann

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

{abridged} We study the imprints on the formation and evolution of cosmic structures of dynamical dark energy models, characterized by an oscillating equation of state. The redshift evolution of the equation of state parameter w(z) for dark…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-19 F. Pace , C. Fedeli , L. Moscardini , M. Bartelmann

We use the non-linear spherical model in cold dark matter (CDM) cosmologies with dark energy to investigate the effects of dark energy on the growth of structure and the formation of virialised structures. We consider dark energy models…

Astrophysics · Physics 2010-12-09 Cathy Horellou , Joel Berge

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 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 intend to understand cosmological structure formation within the framework of superfluid models of dark matter with finite temperatures. Of particular interest is the evolution of small-scale structures where the pressure and superfluid…

Cosmology and Nongalactic Astrophysics · Physics 2020-10-28 S. T. H. Hartman , H. A. Winther , D. F. Mota

We investigate the clustering effect of dark energy (DE) in the formation of galaxy clusters using the spherical collapse model. Assuming a fully clustered DE component, the spherical overdense region is treated as an isolated system which…

Cosmology and Nongalactic Astrophysics · Physics 2017-11-02 Chia-Chun Chang , Wolung Lee , Kin-Wang Ng

We study the nonlinear evolution of matter overdensities using the spherical collapse model in degenerate higher-order scalar-tensor (DHOST) theories beyond Horndeski, employing the effective field theory (EFT) of dark energy approach. We…

Cosmology and Nongalactic Astrophysics · Physics 2025-04-18 Toshiki Takadera , Takashi Hiramatsu , Tsutomu Kobayashi

The present work deals with the spherical collapse of matter overdensity for two reconstructed dark energy models. One of the models is reconstructed from parametrization of effective or total equation of state of energy components in the…

Cosmology and Nongalactic Astrophysics · Physics 2025-03-18 Ankan Mukherjee

We study, for the first time, how shear and angular momentum modify typical parameters of the spherical collapse model, in dark energy dominated universes. In particular, we study the linear density threshold for collapse…

Cosmology and Nongalactic Astrophysics · Physics 2014-02-04 A. Del Popolo , F. Pace , J. A. S. Lima

We investigate a spherical overdensity model for the non-clustering dark energy (DE) with the constant equation of state, w in a flat universe. In this case, the exact solution for the evolution of the scale factor is obtained for general…

Cosmology and Nongalactic Astrophysics · Physics 2010-10-27 Seokcheon Lee , Kin-Wang Ng

The dark energy dominated warm dark matter (WDM) model is a promising alternative cosmological scenario. We explore large-scale structure formation in this paradigm. We do this in two different ways: with the halo model approach and with…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-03 Aurel Schneider , Robert E. Smith , Andrea V. Maccio , Ben Moore
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