Related papers: Structure formation with causal bulk viscosity
As galaxy redshift surveys probe deeper into the universe, they uncover ever more dramatic structures in the large-scale distribution of galaxies. In particular, the CfA2 and SSRS2 surveys to an apparent magnitude limit of 15.5 exhibit an…
Viscous unified dark matter models aim to describe the dark sector of the Universe, as the dark matter fluid itself gives rise to an accelerated expansion due to a negative bulk viscous pressure. However, in most studies, radiation is often…
The universe content is considered as a non-perfect fluid with bulk viscosity and can be described by a general equation of state (endowed some deviation from the conventionally assumed cosmic perfect fluid model). An explicitly bulk…
Nonlocal massive gravity can provide an interesting explanation for the late-time cosmic acceleration, with a dark energy equation of state $w_{\rm DE}$ smaller than $-1$ in the past. We derive the equations of linear cosmological…
We develop a perturbative model to describe large-scale structure in cosmologies where dark matter consists of a mixture of cold (CDM) and warm (WDM) components. In such mixed dark matter (MDM) scenarios, even a subdominant warm component…
Self-gravitating condensates have been proposed as potential candidates for modelling dark matter. In this paper, we numerically investigate the dynamics of dark matter utilizing the merging of self-gravitating condensates. We have used the…
We derive an analytical theory of the PDF of density fluctuations in supersonic turbulence in the presence of gravity in star-forming clouds. The theory is based on a rigorous derivation of a combination of the Navier-Stokes continuity…
We split the total matter fluid into a bound (halo) component and an unbound (free particles) fluid component that is accreted by the halos. We adopt a different framework that treats the structure formation problem as a gravitational…
We examine the possibility of "soft cosmology", namely small deviations from the usual framework due to the effective appearance of soft-matter properties in the Universe sectors. One effect of such a case would be the dark energy to…
In order to study if the bulk viscosity may induce a big rip singularity on the flat FRW cosmologies, we investigate dissipative processes in the universe within the framework of the standard Eckart theory of relativistic irreversible…
In this work we study the evolution of matter-density perturbations for an arbitrary $\Lambda(t)$ model, and specialize our analysis to the particular phenomenological law $\Lambda = \Lambda_0 + 3\beta H^2$. We study the evolution of the…
Bulk viscosity has been intrinsically existing in the observational cosmos evolution with various effects for different cosmological evolution stages endowed with complicated cosmic media. Normally in the idealized "standard cosmology" the…
In the present work, we analyze the evolution of the scalar and tensorial perturbations and the quantities relevant for the physical description of the Universe, as the density contrast of the scalar perturbations and the gravitational…
We present large-scale molecular dynamics simulations to study the free evolution of granular gases. Initially, the density of particles is homogeneous and the velocity follows a Maxwell-Boltzmann (MB) distribution. The system cools down…
Thermodynamic analyses of dark energy as a relativistic fluid indicates that this intriguing component of the universe mimics a bulk viscous pressure when the parameter of its barotropic equation of state varies with time. Since in…
We present an analysis of the clustering evolution of dark matter in four cold dark matter (CDM) cosmologies. We use a suite of high resolution, 17-million particle, N-body simulations which sample volumes large enough to give clustering…
We investigate the non-linear evolution of spherical density and velocity perturbations of dark matter and dark energy in the expanding Universe. For that we have used the conservation and Einstein equations to describe the evolution of…
We report on an experimental observation of classical diffusion distinguishing between structural universality classes of disordered systems in one dimension. Samples of hyperuniform and short-range disorder were designed, characterized by…
A first-principles theory is developed for the general evolution of a key structural characteristic of planar granular systems - the cell order distribution. The dynamic equations are constructed and solved in closed form for a number of…
We explore the growth of structure in multi-species wave (and particle) dark matter. We derive the evolution of the power spectrum of total density contrasts for an arbitrary number of component species, density fractions, and initial field…