相关论文: Damped Lyman Alpha Surveys and Statistics - A Revi…
Absorbers seen in the spectrum of background quasars are a unique tool to select HI-rich galaxies at all redshifts. In turns, these allow to determine the cosmological evolution of the HI gas, Omega_HI+HeII, a possible indicator of gas…
Using Sloan Digital Sky Survey (SDSS) early data release spectra, we have identified 370 MgII absorption systems with MgII 2796 rest equivalent widths >= 1A and redshifts z=0.9-2.2. From our previous and ongoing HST UV spectroscopic…
We have extended our chemical and cosmological galaxy evolution model to calculate the abundance evolution for altogether 16 different elements in spiral galaxies in a chemically consistent way which is a considerable step towards a more…
An unbiased sample of 147 quasar/AGN spectra, obtained with the FOS/HST, has been searched for intervening MgII absorbers over the redshift range 0<z<0.15. The total redshift path searched is 18.8, with the survey being 80% complete to a…
Studies of elemental abundances are a fundamental tool for unveiling the nature of the high-redshift (proto-)galaxies associated to Damped Ly alpha systems (DLAs). The present contribution analyses the impact of dust and ionization effects…
We aim to constrain the average star formation associated with neutral hydrogen gas reservoirs at cosmic noon. Using a unprecedented sample of 1716 high column density Damped Ly-$\alpha$ absorbers (DLAs) from the Sloan Digital Sky Survey…
Hubble Space Telescope (HST) UV spectroscopy of 12 candidate low-redshift damped Lyman alpha (DLA) systems in 11 QSOs (z=0.103 in Q0054+144, z=0.969 and z=0.987 in Q0302-223, z=0.478 in Q0454-220, z=1.476 in Q1047+550, z=1.070 in Q1206+459,…
We present the results of a long-slit K-band spectroscopic search for H-alpha emission from eight damped Ly-alpha absorbers (DLAs) at z>2 with the goal of measuring the star-formation rates in these systems. For each system we searched for…
Measurements of Zn and Cr abundances in damped Lyman alpha systems at absorption redshifts between 0.692 and 3.390 show that metals and dust are much less abundant in high redshift galaxies than in the Milky Way today. We conclude that the…
The damped Lyman alpha systems seen in the spectra of high redshift QSOs offer the means to determine element abundances in galaxies observed while still at an early stage of evolution. Such measurements, which have only recently come…
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…
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 compare chemical abundances of Local Group dwarf spheroidals, obtained from recent UVES/VLT observations, and of high redshift Damped Lyman alpha systems (DLAs), corrected for dust effects. We focus, in particular, on the abundance ratio…
The Damped Lyman-alpha systems (DLAs), seen in absorption in the spectrum of quasars, are believed to contain a large fraction of the neutral gas in the Universe. Paradoxically, these systems are more difficult to observe at z_abs<1.7,…
We have searched the Sloan Digital Sky Survey Data Release 12 for ghostly Damped Ly$\alpha$ (DLA) systems. These systems, located at the redshift of the quasars, show strong absorption from low-ionization atomic species but reveal no HI…
We report the discovery of two damped Ly-alpha absorption-line systems (DLAs) near redshift z=1 along a single quasar sightline (Q1727+5302) with neutral hydrogen column densities of N(HI) = (1.45\pm0.15)\times10^{21} and…
Starting from a summary of detection statistics of our recent X-shooter campaign, we review the major surveys, both space and ground based, for emission counterparts of high-redshift damped Ly$\alpha$ absorbers (DLAs) carried out since the…
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 study the evolution with redshift of the number density of Ly$\alpha$ clouds in a CDM model using numerical simulations including photo-ionization and cooling of the baryonic component. The photo-ionizing flux is consistently taken as…
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…