Related papers: The Cosmological Mass Function in the Zel'dovich A…
We calculate the maximum fraction of matter which is able to condense out of the expanding background universe, for any universe which will expand forever. We use a simple spherical model for the growth of density fluctuations in the…
Astrophysicists do not associate galaxies with the massive dark matter halos so easily detected in particle simulations and whose mass function can be predicted by the Press-Schechter formalism and its variants. Instead, they associate…
We investigate some modifications to the Press & Schechter (1974) (PS) prescription resulting from shear and tidal effects. These modifications rely on more realistic treatments of the collapse process than the standard approach based on…
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…
We investigate the mass functions of different elements of the Large Scale Structure -- walls, pancakes, filaments and clouds -- and the impact of transverse motions -- expansion and/or compression -- on their statistical characteristics.…
The nature of structure formation around the particle free streaming scale is still far from understood. Many attempts to simulate hot, warm, and cold dark matter cosmologies with a free streaming cutoff have been performed with…
An inside-out model for the formation of haloes in a hierarchical clustering scenario is studied. The method combines the picture of the spherical infall model and a modification of the extended Press-Schechter theory. The mass accretion…
In cosmology, a basic explanation of the observed concentration of mass in singular structures is provided by the Zeldovich approximation, which takes the form of free-streaming flow for perturbations of a uniform Einstein-de Sitter…
We compare the mass functions obtained analytically, in the framework of an extended Press & Schechter (PS) formalism, in a previous paper to the numerical mass functions obtained in N -- body simulations, using different algorithms to…
This thesis aims to review the cosmological mass function problem, both from the theoretical and the observational point of view, and to present a new mass function theory, based on realistic approximations for the dynamics of gravitational…
Hydrodynamical simulations are used in combination with the Press-Schechter expression to simulate Sunyaev-Zel'dovich (SZ) galaxy cluster sky maps. These are used to gauge the ability of future SZ observations to provide information about…
In the ellipsoidal collapse model, the critical density for the collapse of a gravitationally bound object is a function of its mass. In the excursion set formalism, this translates into a moving barrier problem such that the mass function…
We carry out N-body simulations of several non-Gaussian structure formation models, including Peebles' isocurvature cold dark matter model, cosmic string models, and a model with primordial voids. We compare the evolution of the cluster…
We discuss the influence of the cosmological background density field on the spherical infall model. The spherical infall model has been used in the Press-Schechter formalism to evaluate the number abundance of clusters of galaxies, as well…
It is well known that the mass function for_halos_ in CDM cosmology is a relatively steep power law for low masses, possibly too steep to be consistent with observations. But how steep is the_galaxy_ mass function? We have analyzed the…
The formalism by Press and Schechter (PS) is often used to infer number densities of virialized objects of mass M (e.g. quasars, galaxies, clusters of galaxies, etc.) from a count of initially overdense regions in a Gaussian density…
We study the spherical collapse model in the presence of quintessence with negligible speed of sound. This case is particularly motivated for w<-1 as it is required by stability. As pressure gradients are negligible, quintessence follows…
We present some preliminary results from a series of extremely large, high-resolution N-body simulations of the formation of early nonlinear structures. We find that the high-z halo mass function is inconsistent with the Sheth-Tormen mass…
If a magnetic field is frozen into a plasma that undergoes spherical compression then the magnetic field B varies with the plasma density \rho according to B \propto \rho^{2/3}. In the gravitational collapse of cosmological density…
We modify the Press-Schechter formalism to calculate the mass function of gravitationally bounded objects in a local Universe with size $L> 10h^{-1}$Mpc, i.e. separately in voids ($\Omega_{m,L}<\Omega_m$) and superclusters…