Related papers: Metallicity Evolution in the Early Universe
Damped Ly$\alpha$ absorbers (DLAs) are the highest \HI\ column density (\NHI) absorption line systems detected in the spectra of background quasars. DLAs dominate the neutral gas content of the Universe ($\Omega_{\rm HI}$) and are used to…
We present the chemical abundance measurements of the first large, medium-resolution, uniformly selected damped Lyman alpha system (DLA) survey. The sample contains 99 DLAs towards 89 quasars selected from the SDSS DR5 DLA sample in a…
We present seven new abundance measurements of the elements O, C and Si at z > 4.5, doubling the existing sample of weakly depleted elements in gas-rich galaxies, in order to constrain the first ~1 billion years of cosmic metal evolution.…
Sub-damped Lyman-alpha systems (sub-DLAs) have previously been found to exhibit a steeper metallicity evolution than the classical damped Lyman-alpha systems (DLAs), evolving to close to solar metallicity by z~1. From new high-resolution…
Measurements of element abundances in damped Lyman alpha systems are providing new means to investigate the chemical evolution of galaxies, particularly at early times. We review progress in this area, concentrating on recent efforts to…
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…
We present a comprehensive analysis of the damped Lya abundance database presented in the first paper of this series. This database provides a homogeneous set of abundance measurements for many elements including Si, Cr, Ni, Zn, Fe, Al, S,…
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…
Interpreting abundances of Damped Ly-$\alpha$ Absorbers (DLAs) from absorption-line spectroscopy has typically been a challenge because of the presence of dust. Nevertheless, because DLAs trace distant gas-rich galaxies regardless of their…
Twenty years of high-resolution spectroscopy at the 8-10 m class telescopes have drastically expanded our view of the gas-phase metallicity in the z>2 universe. This contribution briefly summarizes how these studies reveal a widespread…
Though observationally rare, damped Lya absorption systems dominate the mass density of neutral gas in the Universe. Eleven high redshift damped Lya systems covering 2.8<z<4.4 were discovered in 26 QSOs from the APM z>4 QSO Survey,…
The evolution of the metallicity of damped Lyman alpha systems (DLAs) is investigated in order to understand the nature of these systems. The observational data on chemical abundances of DLAs are analysed with robust statistical methods,…
We study metal abundances in the z=0.9313 damped Lya system observed in the two lines-of-sight, A and B, toward the gravitationally-lensed double QSO HE0512-3329. Spatially resolved STIS spectra constrain the neutral-gas column density to…
We are encouraged by the improving abundance measurements for quasar damped absorption line systems to start a new study of galaxy chemical evolution from high to low redshifts. Our goal is a simple, robust model based on a synthesis of our…
I review the observational characteristics of intermediate-to-high redshift star forming galaxies, including their star formation rates, dust extinctions, ISM kinematics, and chemical compositions. I present evidence that the mean rate of…
We present a comprehensive observational study of the gas phase metallicity of star-forming galaxies from z ~ 0 -> 3. We combine our new sample of gravitationally lensed galaxies with existing lensed and non-lensed samples to conduct a…
We present chemical abundance measurements for 19 damped lya systems observed with HIRES on the 10m W.M. Keck Telescope. Our principal goal is to investigate the abundance patterns of the damped systems and thereby determine the underlying…
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…
The damped Lyman-alpha (DLA) and sub-DLA quasar absorption lines provide powerful probes of the evolution of metals, gas, and stars in galaxies. One major obstacle in trying to understand the evolution of DLAs and sub-DLAs has been the…
I introduce and review the data and analysis techniques used to measure abundances in the damped Lya systems, quasar absorption-line systems associated with galaxies in the early Universe. The observations and issues associated with their…