Related papers: Cosmological Adventures in the Lyman Forest
Observations of redshifted Lyman alpha forest absorption in the spectra of quasistellar objects (QSOs) provide a highly sensitive probe of the distribution of gaseous matter in the universe. Over the past two decades optical spectroscopy…
Cosmological simulations with gas provide a detailed description of the intergalactic medium, making possible predictions of neutral hydrogen absorption in the spectra of background QSOs. We present results from a high-resolution…
Very recently a new inversion method has been developped to analyze the intergalactic medium seen in absorption in quasar spectra (the so-called Lyman-alpha forest). This method is applied to recover the temperature of the gas and the…
The absorption lines observed in quasar spectra have given us a detailed picture of the intergalactic medium and the metal abundance and kinematics of high redshift galaxies. In this review, we present an introduction to the field, starting…
We present an analysis of the proximity effect in a sample of ten 2 A resolution QSO spectra of the Ly alpha forest at <z> = 2.9. Rather than investigating variations in the number density of individual absorption lines we employ a novel…
Lyman-alpha forest lines in QSO spectra have typical widths of 20-50 km/s. Low column density absorbers in cosmological simulations are large, diffuse structures, and the Hubble flow across the spatially extended absorber is usually the…
We have compiled, from the literature, a sample of Ly ${\alpha}$ forest lines in the spectra of 69 QSOs, all observed with a resolution between 60 to 100 km s$^{-1}$. The sample is studied for proximity effect. We have tried to account for…
We present some statistical features of the large number of \lya absorption lines detected in high redshift quasar spectra, obtained by using the multifractal approach. In the analysed sample of 12 QSO sight--lines, 11 show scaling…
Lyman alpha absorber correlations contain information about the underlying density distribution associated with a particular class of absorbers. As such, they provide an opportunity to independently measure the "bias" of the Lyman alpha…
This paper describes a study of the Lyman-alpha forest absorption clouds along the quasar sightline Q0000-26 (zem=4.1). The spectrum was obtained with the High Resolution Spectrometer on the 10m Keck telescope. We derive accurate H I column…
We present a model for the Lyman-alpha absorbers that treats all objects (from the low-density forest clouds to the dense damped systems) in a unified description. This approach is consistent with an earlier model of galaxies (luminosity…
The influence of a foreground QSO on the lyman a forest of another QSO with higher redshift has been investigated by analyzing the spectra of three such objects at redshifts $z=2 - 2.7$. This influence is not contaminated by any projection…
The spatial distribution of Ly-alpha forest absorption systems towards ten QSOs has been analysed to search for large-scale structure over the redshift range 2.2 < z < 3.4. The QSOs form a closely spaced group on the sky and are…
The spatial distribution of Ly-alpha forest absorption systems toward a group of 8, closely spaced QSOs has been analysed and evidence for large scale structure has been found at <z> = 2.8. Our technique is based on the first and second…
We examine the Ly-alpha absorber population at z<0.3 detected in spectra of the QSOs PG0953+415 and H1821+643 taken with the Space Telescope Imaging Spectrograph aboard the Hubble Space Telescope. We compare their statistical properties to…
Observations of absorption systems in close, multiple lines of sight to gravitationally lensed QSOs can be used to infer the density fluctuations and motions of the gas clouds giving rise to the Lyman alpha forest phenomenon and to QSO…
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…
The low-redshift evolution of the intergalactic medium is investigated using hydrodynamic cosmological simulations. The assumed cosmological model is a critical density cold dark matter universe. The imposed uniform background of ionizing…
It is shown that many properties of Ly-alpha forest absorbers can be derived using simple physical arguments. Analytical expressions are derived for the density and the size of an absorber as a function of its neutral hydrogen column…
We investigate the properties of the Lyman alpha forest as predicted by numerical simulations for a range of currently viable cosmological models. This is done in order to understand the dependencies of the forest on cosmological…