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The effects that large scale fluctuations had on small scale isothermal modes at the epoch of recombination are analysed. We find that: (a) Albeit the fact that primordial fluctuations were at this epoch still well in the linear regime, a…

Astrophysics · Physics 2009-10-30 Nir J. Shaviv

Persisting tensions between the cosmological constraints derived from low-redshift probes and the ones obtained from temperature and polarisation anisotropies of the Cosmic Microwave Background -- although not yet providing compelling…

Cosmology and Nongalactic Astrophysics · Physics 2016-12-14 Marco Baldi , Fergus Simpson

We examine linear perturbation theory to evaluate the contribution of viscosity coefficient in the growing of dark matter perturbations in the context of the bulk viscous dark energy model inspired by thermodynamical dissipative phenomena…

Cosmology and Nongalactic Astrophysics · Physics 2018-10-12 B. Mostaghel , H. Moshafi , S. M. S. Movahed

We study the non-linear structure formation in cosmology accounting for the quantum nature of the dark matter (DM) particles in the initial conditions at decoupling, as well as in the relaxation and stability of the DM halos. Differently…

Astrophysics of Galaxies · Physics 2022-03-14 Carlos R. Argüelles , Eduar A. Becerra-Vergara , Andreas Krut , Rafael Yunis , Jorge A. Rueda , Remo Ruffini

We study the dynamical effect of relative velocities between dark matter and baryonic fluids, which remained supersonic after the epoch of recombination. The impact of this supersonic motion on the formation of cosmological structures was…

Cosmology and Nongalactic Astrophysics · Physics 2016-10-26 Kyungjin Ahn

We investigate the evolution of density perturbations in dark matter, including the new combined effects of finite number density and non-zero velocity dispersion. Using a truncated BBGKY hierarchy, we derive analytical expressions for the…

Cosmology and Nongalactic Astrophysics · Physics 2026-01-09 Mustafa A. Amin , M. Sten Delos , Mehrdad Mirbabayi

Increasing attention has recently focused on non-traditional dark-matter production mechanisms which result in primordial dark-matter velocity distributions with highly non-thermal shapes. In this paper, we undertake an assessment of how…

Cosmology and Nongalactic Astrophysics · Physics 2022-10-14 Keith R. Dienes , Fei Huang , Jeff Kost , Kevin Manogue , Brooks Thomas

We investigate the cosmological dynamics of interacting dark energy within the framework of $\alpha$-attractor models. Specifically, we analyze the associated autonomous system, focusing on its fixed points that represent dark energy and…

General Relativity and Quantum Cosmology · Physics 2025-12-04 L. K. Duchaniya , B. Mishra , G. Otalora , M. Gonzalez-Espinoza

Unified dark matter cosmologies economically combine missing matter and energy in a single fluid. Of these models, the standard Chaplygin gas is theoretically motivated, but faces problems in explaining large scale structure if linear…

Cosmology and Nongalactic Astrophysics · Physics 2022-10-12 Abdelrahman Abdullah , Amr El-Zant , Ali Ellithi

We explore local consequences of a non-zero cosmological constant on astrophysical structures. We find that the effects are not only sensitive to the density of the configurations but also to the geometry. For non-homogeneous…

Astrophysics · Physics 2010-12-13 Marek Nowakowski , Andres Balaguera-Antolinez

We study the formation of non-linear structures in Warm Dark Matter (WDM) models and in a Long-Lived Charged Massive Particle (CHAMP) model. CHAMPs with a decay lifetime of about 1 yr induce characteristic suppression in the matter power…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-12 Ayuki Kamada , Naoki Yoshida , Kazunori Kohri , Tomo Takahashi

We study the concentration parameters, their mass dependence and redshift evolution, of dark-matter halos in different dark-energy cosmologies with constant and time-variable equation of state, and compare them with "standard'' Lambda-CDM…

A new phenomenological dark energy model, originally associated to the large-scale structure formation and considered as a solution to the fine-tuning and coincidence problems related to the cosmological constant, was analyzed within the…

General Relativity and Quantum Cosmology · Physics 2026-03-05 A. Kazım Çamlıbel

The recently proposed Multi-coupled Dark Energy (McDE) scenario - characterised by two distinct Cold Dark Matter (CDM) particle species with opposite couplings to a Dark Energy scalar field - introduces a number of novel features in the…

Cosmology and Nongalactic Astrophysics · Physics 2014-03-12 Marco Baldi

The growth and virialization of spherical top-hat fluctuations, in coupled Dark Energy models, causes segregation between Dark Matter (DM) and baryons, as the gravitational infall into the potential well proceeds more slowly for the baryons…

Astrophysics · Physics 2009-11-13 Roberto Mainini

We consider the evolution of linear perturbations in models with a nonminimal coupling between dark matter and scalar field dark energy. Growth of matter inhomogeneities in two examples of such models proposed in the literature are…

Astrophysics · Physics 2009-11-11 Tomi Koivisto

We disclose the effects of an extra longitudinal degree of freedom on the evolution of perturbations in the framework of mimetic gravity. We consider a flat Friedmann-Robertson-Walker (FRW) background and explore the linear perturbations by…

General Relativity and Quantum Cosmology · Physics 2022-08-02 Bita Farsi , Ahmad Sheykhi

We revisit a cosmological model where dark matter (DM) and dark energy (DE) follow barotropic equations of state, allowing deviations from the standard $\Lambda$CDM framework (i.e. $w_{dm} \neq 0$, $w_{de} \neq -1$), considering both flat…

Cosmology and Nongalactic Astrophysics · Physics 2025-11-24 Dorian Araya , Cristian Castillo , Genly Leon , Juan Magaña , Angie Barr Domínguez , Miguel A. García-Aspeitia

We study dynamical dark energy models that allow for general late time behaviour while admitting non-phantom dynamics at early times, including thawing, scaling$+$thawing, and effective fluid extensions. Using current cosmological data, we…

Cosmology and Nongalactic Astrophysics · Physics 2025-12-24 Sk. Sohail , Sonej Alam , Md. Wali Hossain

We use the integrated Sachs-Wolfe (ISW) effect, by now detectable at $\sim 5\sigma$ within the context of $\Lambda{}$CDM cosmologies, to place strong constraints on dynamical dark energy theories. Working within an effective field theory…

Cosmology and Nongalactic Astrophysics · Physics 2024-07-18 Emeric Seraille , Johannes Noller , Blake D. Sherwin