Related papers: Chemical Evolution of Damped Lyman Alpha Systems
The evolution of the metal content of the universe can be tracked through rest-frame UV spectroscopy of damped Ly-$\alpha$ systems (DLAs). Gas-phase abundances in DLAs must be corrected for dust depletion effects, which can be accomplished…
Observations of low mean metallicity of damped Lyman-alpha (DLA) quasar absorbers at all redshifts studied appear to contradict the predictions for the global mean interstellar metallicity in galaxies from cosmic chemical evolution models.…
Previously we have shown that it is possible to account for the kinematic properties of damped Lyman alpha systems (DLAS) in the context of semi-analytic models. In these models, hierarchical structure formation is approximated by…
We examine in detail the dynamical structure of an elliptical galaxy simulated in the Lambda CDM scenario. The morphology of the galaxy evolves dramatically over time in response to the mode and timing of mass accretion; smooth deposition…
Some aspects of the chemical evolution of late-type dwarf galaxies are reviewed, together with their implications on three issues of cosmological relevance: similarity to primeval galaxies, derivation of the primordial helium abundance,…
We report results on the incidence and cosmological mass density of damped Lyman-alpha (DLA) systems at redshifts less that 1.65. We used HST and an efficient non-traditional (but unbiased) survey technique to discover DLA systems at…
The similarity between observed velocity structures of Al III and singly ionised species in damped Lyman-alpha systems (DLAs) suggests the presence of ionised gas in the regions where most metal absorption lines are formed. To explore the…
We report the discovery and analysis of the most metal-poor damped Lyman-alpha (DLA) system currently known, based on observations made with the Keck HIRES spectrograph. The metal paucity of this system has only permitted the determination…
We investigate the nature of the physical structures giving rise to damped Lyman alpha absorption systems (DLAS) at high redshift. In particular, we examine the suggestion that rapidly rotating large disks are the only viable explanation…
We present high resolution echelle spectra of 7 proximate damped Lyman alpha (PDLA) systems whose relative velocity separation from the background quasar is Delta V < 3000 km/s. Combining our sample with a further 9 PDLAs from the…
We present a sample of 38 intervening Damped Lyman $\alpha$ (DLA) systems identified towards 100 $z>3.5$ quasars, observed during the XQ-100 survey. The XQ-100 DLA sample is combined with major DLA surveys in the literature. The final…
The chemical abundance patterns of near-pristine objects provide important constraints on the properties of the first generations of stars in the Universe. We present the chemical abundances of five very metal-poor ([M/H]<-2.5) sub damped…
We present Giant Metrewave Radio Telescope HI 21cm absorption observations, of candidate and confirmed damped Lyman-$\alpha$ systems (DLAS). The derived spin temperatures (T_s) are in all cases $\sim 1000$ K or higher. We have also collated…
We report on the first Cosmic Origins Spectrograph (COS) observations of damped and sub-damped Lyman-alpha (DLA) systems discovered in a new survey of the gaseous halos of low-redshift galaxies. From observations of 37 sightlines, we have…
We present a large sample of fully self-consistent hydrodynamical Nbody/Tree-SPH simulations of isolated dwarf spheroidal galaxies (dSphs). It has enabled us to identify the key physical parameters and mechanisms at the origin of the…
We present preliminary results from the Hamburg/ESO survey for Damped Ly-alpha (hereafter, DLA) Systems. This survey is characterized by (i) the good knowledge of the biases affecting the parent QSO survey, (ii) the brightness and (iii) the…
We employ observationally determined intrinsic velocity widths and column densities of damped Lyman-alpha systems at high redshift to investigate the distribution of baryons in protogalaxies within the context of a standard cold dark matter…
We present the first results from a survey of SDSS quasars selected for strong H I damped Lyman-{\alpha} (DLA) absorption with corresponding low equivalent width absorption from strong low-ion transitions (e.g. C II {\lambda}1334 and Si II…
We explore a range of chemical evolution models for the Local Group dwarf spheroidal (dSph) galaxy, Carina. A novel aspect of our work is the removal of the star formation history (SFH) as a `free parameter' in the modeling, making use,…
The most metal-poor, high redshift damped Lyman-alpha systems (DLAs) provide a window to study some of the first few generations of stars. In this paper, we present a novel model to investigate the chemical enrichment of the near-pristine…