Related papers: Abundance Patterns of Heavy Elements in Damped Lym…
Observations of absorption lines in the spectra of distant QSOs offer a new approach for tracking the evolution of normal galaxies from early epochs to the present day. The damped Ly alpha systems are particularly suitable for measuring the…
High resolution spectra of 34 halo population dwarf and subgiant stars have been obtained with VLT/UVES and used to derive sulphur abundances from the 8694.0, 8694.6 A and 9212.9, 9237.5 A SI lines. In addition, iron abundances have been…
Our knowledge of galactic chemical evolution is currently limited to observations of Milky Way stars and H II regions of nearby galaxies. Damped Lyman~$\alpha$ systems offer a new approach for tracking the evolution of normal galaxies from…
Damped Ly-alpha Systems (DLAs), with N(HI)>2*10^20 cm^{-2}, observed in quasars have allowed us to quantify the chemical content of the Universe over cosmological scales. Such studies can be extended to lower N(HI), in the sub-DLA range…
In this paper we analyze the kinematics, chemistry, and physical properties of a sample of the most metal-poor damped Lyman-alpha systems (DLAs), to uncover their links to modern-day galaxies. We present evidence that the DLA population as…
The Damped and sub-Damped Lyman-alpha (DLA and sub-DLA) systems seen in the spectra of QSOs offer a unique way to study the interstellar medium of high redshift galaxies. In this paper we report on new abundance determinations in a sample…
We investigate chemical enrichment in Damped Lyman alpha (DLA) systems in the hierarchical structure formation scenario using a semi-analytic model of galaxy formation. The model developed by Nagashima, Totani, Gouda and Yoshii takes into…
By combining our UVES-VLT spectra of a sample of four damped Ly-alpha systems (DLAs) toward the quasars Q0100+13, Q1331+17, Q2231-00 and Q2343+12 with the existing HIRES-Keck spectra, we covered the total spectral range from 3150 to 10000 A…
An analytical expression is presented that allows dust depletions to be estimated in different types of interstellar environments, including Damped Ly alpha systems. The expression is a scaling law of a reference depletion pattern and takes…
Damped Ly alpha clouds provide information on the chemistry of distant and metal poor regions of the universe. In these clouds for observational difficulties N and O are among the last elements to be measured, and C has still to be measured…
We present 4 new measurements of nitrogen abundances and one upper limit in damped Lyman alpha absorbers (DLAs) obtained by means of high resolution (FWHM \~ 7 km/s) UVES/VLT spectra. In addition to these measurements we have compiled data…
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…
Although damped Lyman alpha (DLA) systems are usually considered metal-poor, it has been suggested that this could be due to observational bias against metal-enriched absorbers. I review recent surveys to quantify the particular issue of…
Motivated by the anomalous dust-to-metal ratios derived in the literature for gamma-ray burst (GRB) damped Lyman-alpha absorbers (DLAs), we measure these ratios using the dust-depletion pattern observed in UV/optical afterglow spectra…
Observations of the QSO 0000-2620 with UVES spectrograph at the 8.2m ESO KUEYEN telescope are used for abundance analysis of the damped Ly-alpha system at z_{abs}=3.3901. Several Oxygen lines are identified in the Ly_alpha forest and a…
A previous study (Nissen & Schuster 2010) of 94 dwarf stars with -1.6 < [Fe/H] < -0.4 has revealed the existence of two distinct halo populations with a systematic difference in [alpha/Fe] at a given metallicity. In continuation of that…
Galactic chemical evolution model calculations indicate that there should be considerable scatter in the observed N/O ratios at a fixed metallicity (O/H) for galaxies with very low metallicities due to the delayed release of primary N from…
[Abridged] Motivated by upcoming data from astrometric and spectroscopic surveys of the Galaxy, we explore the chemical abundance properties and phase-space distributions in hierarchically-formed stellar halo simulations set in a LambdaCDM…
Any viable cosmological model must produce enough structure at early epochs to explain the amount of gas associated with high-redshift damped Ly$\alpha$ systems. We study the evolution of damped Ly$\alpha$ systems at redshifts $z\ge 2$ in…
We present HST spectra for a sample of six QSOs with intermediate redshift (z_a < 1) damped Ly-alpha systems. These observations aim at measuring the HI column density and detect metal lines in order to investigate the metal enrichment of…