Related papers: Metallicity Evolution in the Early Universe
We present accurate metallicity measurements for 121 damped Lya systems at 0.5<z<5 including ~50 new measurements from our recently published Echellette Spectrograph and Imager surveys. This dataset is analysed to determine the…
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…
We have reanalyzed the existing data on Zinc abundances in damped Ly-alpha (DLA) absorbers to investigate whether their mean metallicity evolves with time. Most models of cosmic chemical evolution predict that the mass- weighted mean…
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…
According to Pei, Fall & Hauser (1999), the global metallicity evolution of the Universe can be represented by the ratio of the total metal content to the total gas content measured in Damped Lyman-alpha (DLA) systems (the ``column density…
Using the redshift evolution of the neutral hydrogen density, as inferred from observations of damped Ly$\alpha$ clouds, we calculate the evolution of star formation rates and elemental abundances in the universe. For most observables our…
We have collected data for 69 Damped Lyman-alpha (DLA) systems, to investigate the chemical evolution of galaxies in the redshift interval 0.0 < z < 4.4. In doing that, we have adopted the most general approach used so far to correct for…
We present the first results from an ongoing survey to discover and measure the metallicity of z>3 damped Lya systems with the Echellette Spectrograph and Imager (ESI) on the Keck II telescope. Our motivation arises from a recent study on…
We use cosmological hydrodynamical simulations including star formation and metal enrichment to study the evolution of the chemical properties of galaxy-like objects at high redshift in the range $0.25<z< 2.35$ in a hierarchical clustering…
Utilizing a new, high mass resolution hydrodynamic simulation we compute the metallicity evolution of damped Lyman alpha systems (DLAs) and find a reasonable agreement with observations. In particular, the observed slow evolution of the DLA…
We explore the redshift evolution of the metal content of damped Lyman alpha systems (DLAs) with new observations of four absorbers at z < 1.5 . The main conclusion is that the column density--weighted mean metallicity, [<Zn/H>] = -1.03 +/-…
Assuming that damped Lyman-alpha(DLA) systems are galactic discs, we calculate the corresponding evolution of metal abundances. We use detailed multi-zone models of galactic chemical evolution (reproducing successfully the observed…
We apply the phenomenological model used to explain the abundances of Fe and r-process elements in very metal-poor stars in the Galaxy to [Fe/H] of damped Ly alpha systems. It is assumed that the first stars formed after the Big Bang were…
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…
We present a model for chemical evolution of damped Ly alpha systems considering production of metals by SNe II and infall associated with hierarchical structure formation. The growth of metallicity in these systems is a reflection of the…
Relative elemental abundances, and in particular the alpha/Fe ratio, are an important diagnostic tool of the chemical evolution of damped Ly alpha systems (DLAs). The S/Zn ratio is not affected by differential dust depletion and is an…
We report new observations of ZnII and CrII absorption lines in 10 damped \lya systems (DLAs), mostly at redshift $z_{abs} \simgt 2.5$ . By combining these results with those from our earlier survey (Pettini et al. 1994) and other recent…
We present chemical abundance measurements for 47 damped Lyman-alpha systems (DLAs), 30 at z>4, observed with the Echellette Spectrograph and Imager and the High Resolution Echelle Spectrometer on the Keck telescopes. HI column densities of…
We present evidence that the cosmological mean metallicity of neutral atomic hydrogen gas shows a sudden decrease at z>4.7 down to <Z>=-2.03(+0.09-0.11), which is 6 sigma deviant from that predicted by a linear fit to the data at lower…
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.…