Related papers: The Ly-alpha forest in a truncated hierarchical st…
Many recent studies have demonstrated that scaling arguments, such as the so-called hierarchical {\em ansatz}, are extremely useful in understanding the statistical properties of weak gravitational lensing. This is especially true on small…
The scatter in the apparent magnitude of type Ia supernovae induced by stochastic gravitational lensing is highly dependent on the nonlinear growth of cosmological structure. In this paper, we show that such a dependence can potentially be…
On large scales, the Lyman-$\alpha$ forest provides insights into the expansion history of the Universe, while on small scales, it imposes strict constraints on the growth history, the nature of dark matter, and the sum of neutrino masses.…
Models for structure formation attempt to predict the power spectrum of density perturbations in the present universe from the initial power spectrum and the nature of dark matter. Observational constraints on the power spectrum at…
There is a general agreement that galaxy structures exhibit fractal properties, at least up to some small scale. However the presence of an eventual crossover towards homogenization, as well as the exact value of the fractal dimension, are…
The mean power spectrum of galaxies is compared with theoretical models. Possibilities to explain the observed power spectrum are discussed. Superclusters and voids form a quasi-regular lattice of mean cell size 120 Mpc; the main axis of…
How is the universe organized on large scales? How did this structure evolve from the unknown initial conditions of a rather smooth early universe to the present time? The answers to these questions will shed light on the cosmology we live…
We address the problem of inferring the three-dimensional matter distribution from a sparse set of one-dimensional quasar absorption spectra of the Lyman-$\alpha$ forest. Using a Bayesian forward modelling approach, we focus on extending…
A simple consistency argument for hypothesis of the galactic halo origin of the Ly-alpha forest absorption lines is advanced, based on the recent determination of column-density vs. impact parameter relation for the low-redshift gaseous…
We present the analysis of a sample of the Ly-$\alpha$ forest spectra of 152 quasars taken with the HST FOS. The Ly-$\alpha$ lines show little evolution at $0<z<1.7$. We see a difference between the evolution indices for weak and strong…
We investigate correlations between the long wavelength fluctuations and the small scale power in the Lyman alpha forest. We show that such correlations can be used to discriminate between fluctuations induced by large scale structure and…
The properties of spatial distribution of luminous matter are investigated analysing all the available three dimensional catalogues of galaxies. In standard view, galaxies are believed to have a fractal distribution at small scale with a…
The Lyman-alpha forest at z >~ 5.5 shows strong scatter in the mean transmission even when smoothed over very large spatial scales, >~ 50 Mpc/h. This has been interpreted as a signature of strongly fluctuating radiation fields, or patchy…
We have carried out a multi-fractal analysis of the distribution of galaxies in the three Northern slices of the Las Campanas Redshift Survey. Our method takes into account the selection effects and the complicated geometry of the survey.…
The evolution of the temperature distribution function (TDF) of X-ray clusters is kn own to be a powerful cosmological test of the density parameter of the Universe. Recent XMM observations allows us to measure accurately the L - T relation…
We examine the proposal that a model of the large-scale matter distribution consisting of randomly placed haloes with power-law profile, as opposed to a fractal model, can account for the observed power-law galaxy-galaxy correlations. We…
In recent years, a remarkably simple physical picture of the Lyman-alpha forest has emerged, which allows detailed predictions to be made and turns the forest into a powerful probe of cosmology. We point out ways in which such a picture can…
When measuring the one-dimensional power spectrum of the Ly$\alpha$ forest, it is common to measure the power spectrum in flux fluctuations red-ward of the Ly$\alpha$ emission of quasars and subtract this power from the measurements of the…
We present a new approach to the statistics of the cosmic density field and to the mass distribution of high-contrast structures, based on the formalism of Cayley trees. Our approach includes in one random process both fluctuations and…
Motivated by observational and theoretical work which both suggest very small scale ($\lesssim 1\,$pc) structure in the circum-galactic medium of galaxies and in other environments, we study Lyman-$\alpha$ (Ly$\alpha$) radiative transfer in…