Related papers: MODELS OF LYMAN-ALPHA CLOUDS
The HI Parkes All Sky Survey (HIPASS) galaxy catalogue is cross-correlated with known low redshift, low column density (N_HI <10^15 cm^-2) Lyman-alpha absorbers from the literature. The redshift-space correlation is found to be similar in…
In this Letter we explore a version of the test of cosmological geometry proposed by Alcock and Paczynski (1979), using observations of the Lyman-alpha forest in the spectra of close quasar pairs. By comparing the correlations in absorption…
The COBE microwave background temperature fluctuations and the abundance of local rich clusters of galaxies provide the two most powerful constraints on cosmological models. When all variants of the standard cold dark matter (CDM) model are…
It is suggested that a significant fraction of the low column-density absorption features seen in the spectra of quasars are produced in pressure-confined tidal debris, that was built up in small groups and clusters of galaxies over a…
Lyman-$\alpha$(Ly$\alpha$) forest in the spectra of distant quasars encodes the information of the underlying cosmic density field at smallest scales. The modelling of the upcoming large and high-fidelity forest data using cosmological…
The standard cosmological model, now strongly constrained by direct observation at early epochs, is very successful in describing the structure of the evolved universe on large and intermediate scales. Unfortunately, serious contradictions…
We present a semi-analytical model to test the hypothesis that Ly-alpha QSO absorption lines originate in gaseous halos produced by multiple supernova explosions occurring in Pop III objects in a CDM cosmological scenario hoping to assess…
We study radiation pressure due to Lyman alpha line photons, obtaining and exploring analytical expressions for the force-multiplier, $M_F(N_H, Z) = F_\alpha/(L_\alpha/c)$, as a function of gas column density, $N_H$, and metallicity, $Z$,…
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.…
Various recent studies proved that cosmological models with a significant contribution from cold dark matter isocurvature perturbations are still compatible with most recent data on cosmic microwave background anisotropies and on the shape…
We use LUQAS, a sample of 27 high resolution high signal-to-noise UVES quasar (QSO) spectra (Kim et al. 2004), and the Croft et al. (2002) sample together with a set of high resolution large box size hydro-dynamical simulations run with the…
Higher order clustering statistics of Ly$\alpha$ forest provide a unique probe to study non-gaussianity in Intergalactic matter distribution up to high redshifts and from large to small scales. The author presents a brief review of his work…
High-redshift Lyman-alpha blobs (LABs) are an enigmatic class of objects that have been the subject of numerous observational and theoretical investigations. It is of particular interest to determine the dominant power sources for the…
The origin and evolution of structure in the Universe is one of the major questions occupying astronomers today. An understanding of the Lyalpha absorbers seen in QSO spectra is an important part of this program since such absorbers can be…
The recent discovery of carbon in close to half of the low neutral hydrogen column density [$N({\rm H~I}) > 3\ten{14}\cm2$] Lyman forest clouds toward $z \sim 3$ quasars has challenged the widely held view of this forest as a chemically…
I discuss recent HST observations and interpretation of low-z Ly-alpha clouds toward nearby Seyferts and QSOs, including their frequency, space density, estimated mass, association with galaxies, and contribution to Omega_b. Our HST/GHRS…
We examine the statistics of the low-redshift Ly-alpha forest in an adaptive mesh refinement hydrodynamic cosmological simulation of sufficient volume to include distinct large-scale environments. We compare our HI column density…
We determine the product of the expansion rate and angular-diameter distance at redshift $z=2.3$ from the anisotropy of Lyman-$\alpha$ (Ly$\alpha$) forest correlations measured by the Sloan Digital Sky Survey (SDSS). Our result is the most…
High-resolution N--body simulations show a remarkable similarity in the structure of dark matter halos formed through dissipationless hierarchical clustering. Independent of halo mass, power spectrum, and cosmological parameters, the…
In this paper we critically examine predictions of the Lya forest within the standard cold dark matter (SCDM) model, paying particular attention to the low end of the column-density distribution. We show in particular that the width of…