Related papers: Metallicity Evolution of Damped Lyman Alpha System…
Damped Ly-alpha absorbers (DLAs) can be used to measure gas-phase metallicities at large cosmological lookback times with high precision. Relative abundances can still be measured accurately deep into the reionization epoch (z > 6) using…
We estimate the intrinsic neutral gas density in Damped Lyman Alpha systems ($\Omega_{HI}^{(DLA)}$) in the redshift range $ 2.2 \lesssim z \lesssim 5$ from the DLA SDSS DR_3 sample of optically selected quasars. We take into account…
We show that the extinction of quasar absorbers increases exponentially with the logarithmic column density of any volatile metal (e.g. zinc), with a charateristic turning point above which the quasars are severely dimmed. We derive the…
We study the distribution of star formation rate (SFR) and metallicity of damped Lyman-alpha absorbers (DLAs) using cosmological smoothed particle hydrodynamics (SPH) simulations of the Lambda cold dark matter model. Our simulations include…
We present the measured gas-phase metal column densities in 155 sub-damped Lyman alpha systems (subDLAs) with the aim to investigate the contribution of subDLAs to the chemical evolution of the Universe. The sample was identified within the…
We report spectroscopic observations with the Multiple Mirror Telescope for 11 damped Lyman-alpha absorbers (DLAs) or strong DLA candidates at 0.1 < z < 1.5, including several absorbers discovered in the Sloan Digital Sky Survey. In…
We discuss our recent results on the statistical properties of damped Lyman alpha systems (DLAs) at low redshift (z<1.65) (Rao & Turnshek 2000). Contrary to expectations, we found that the cosmological neutral gas mass density as traced by…
We investigate the evolutionary history of the Universe's metal content focusing on the chemical abundance of several elements (N, O, S, Si, Fe, Cr, Zn) taken from observational data and predictions from chemical evolution models. The…
The main properties of Damped Lyman alpha (DLA) systems are briefly reviewed with the aim of studying the nature and evolution of the galaxies associated with this class of QSO absorbers. Candidate DLA galaxies identified at z </= 1 in the…
A powerful technique to trace the signatures of the first stars is through the metal enrichment in concentrated reservoirs of hydrogen, such as the damped Lyman-alpha absorbers (DLAs) in the early universe. We conducted a survey aimed at…
The history and progress of DLA research over the past several decades is reviewed here. Larger datasets and deeper surveys, particularly over the last couple of years, have improved our knowledge of the neutral gas content and distribution…
We consider the questions of whether the damped Lyman-alpha (DLA) and sub-DLA absorbers in quasar spectra differ intrinsically in metallicity, and whether they could arise in galaxies of different masses. Using the recent measurements of…
We present metal abundances in 15 damped Lyman alpha systems (DLAs) from the Complete Optical and Radio Absorption Line System (CORALS) survey, designed to be free from any biasing effects due to extinction of QSOs by dust in intervening…
We investigate the population of z=3 damped Lyman alpha absorbers (DLAs) in a recent series of high resolution galaxy formation simulations. The simulations are of interest because they form at z=0 some of the most realistic disk galaxies…
We analyze the redshift evolution of the mass-metallicity relation in a sample of 110 Damped Ly$\alpha$ absorbers spanning the redshift range $z=0.11-5.06$ and find that the zero-point of the correlation changes significantly with redshift.…
We present a study of the early build-up of dust in high redshift galaxies. The study is based on the analysis of 38 Damped Ly alpha systems (DLAs) for which we derive the fraction of iron atoms in dust form, f_{Fe}. The sample is…
Observations of the damped Lya systems provide direct measurements on the chemical enrichment history of neutral gas in the early universe. In this Letter, we present new measurements for four damped Lya systems at high redshift. Combining…
We describe the evolution of galaxies in a chemically consistent way accounting for the increasing initial metallicity of successive generations of stars. The enrichment of various types of model galaxies is compared with Damped Ly$\alpha$…
We investigate the properties of Damped Lyman-alpha systems (DLAs) using high-resolution and large box-size cosmological hydrodynamical simulations of a LambdaCDM model. The numerical code used is a modification of GADGET-2 with a self…
We present the first theoretical study of metals in damped Ly-alpha (DLA) systems at redshift z=7. The features of cold, primordial gas are studied by means of N-body, hydro, chemistry simulations, including atomic and molecular…