相关论文: Elemental Abundances in QSOs: Star Formation and G…
High redshift quasars mark the locations where massive galaxies are rapidly being assembled and forming stars. There is growing evidence that quasar environments are metal-rich out to redshifts of at least five. The gas-phase metallicities…
Intrinsic emission and absorption lines of QSOs provide several independent probes of the metal abundances in QSO environments. They indicate that the metallicities are typically solar or higher out to redshifts z > 4. These results support…
The heavy elements near QSOs provide unique measures of the star formation and chemical evolution in young galactic nuclei or pre-galactic condensations. Studies of quasar abundances also naturally address a variety of questions regarding…
Quasars are powerful systems whose spectrum is rich of metal features that allow us to investigate the chemical evolution of galaxies at very high redshift, even close to the reionization epoch. I review the main observational constraints…
Studies of the broad emission-line regions (BLRs) in quasars have revealed solar or higher enrichment levels up to the highest redshifts. In combination with the presence of large amounts of dust in QSOs at $z$ about 6, this implies that…
We examine rest-frame ultraviolet spectra of 70 high redshift quasars (z>3.5) to study the chemical enrichment history of the gas closely related to the quasars, and thereby estimate the epoch of first star formation. The fluxes of several…
We compare the metallicities in high-redshift quasars to the star formation rates (SFR) in their host galaxies using measurements of broad emission lines and far-infrared (FIR) luminosities. The FIR emission indicates the level of ongoing…
The past few years have seen a steady progress in the determination of element abundances at high redshifts, with new and more accurate measures of metallicities in star-forming galaxies, in QSO absorbers, and in the intergalactic medium.…
Quasars signal a unique phase of galaxy evolution -- when massive spheroids are rapidly being assembled, forming stars and growing their central super-massive black holes. Measurements of the metal abundances around quasars provide unique…
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…
The abundance of alpha-process elements such as magnesium and carbon relative to iron measured from the broad emission lines of QSOs can serve as a diagnostic of the star formation and chemical enrichment histories of their host galaxies.…
In order to derive information on the star formation history in the early universe we observed 6 high-redshift (z=3.4) quasars in the near-infrared to measure the relative iron and \mgii emission strengths. A detailed comparison of the…
We determined C, N and alpha-element relative abundances in the gas surrounding six QSOs at an average redshift of < z > ~ 2.4, by studying six narrow associated absorption systems in UVES high-resolution spectra. We found five systems with…
Element abundances in high-redshift quasar absorbers offer excellent probes of the chemical enrichment of distant galaxies, and can constrain models for population III and early population II stars. Recent observations indicate that the…
The abundance patterns of metal-poor stars provide us a wealth of chemical information about various stages of the chemical evolution of the Galaxy. In particular, these stars allow us to study the formation and evolution of the elements…
Direct and indirect observational evidence leads to the conclusion that high redshift QSOs did shine in the core of early type proto-galaxies during their main episode of star formation. Exploting this fact, we derive the rate of formation…
The chemical composition of high-redshift galaxies is an important property that gives clues to their past history and future evolution. Measuring abundances in distant galaxies with current techniques is often a challenge, and the…
Quasars are among the most luminous objects in the universe, and they can be studied in detail up to the highest known redshift. Assuming that the gas associated with quasars is closely related to the interstellar medium of the host galaxy,…
Abundance histories for QSO absorption line systems as a function of redshift are presented for all metals lighter than gallium. Coupling various conventional cosmological models with a simple, first--order model for the chemical evolution…
We present observations of 11 high redshift quasars ($3.9 \la z \la 5.0$) observed with low spectral resolution in the restframe ultraviolet using FORS 1 at the VLT UT 1. The emission-line fluxes of strong permitted and intercombination…