Abundances in Damped Lyα Galaxies
نویسنده
چکیده
Damped Lyα galaxies provide a sample of young galaxies where chemical abundances can be derived throughout the whole universe with an accuracy comparable to that for the local universe. Despite a large spread in redshift, HI column density and metallicity, DLA galaxies show a remarkable uniformity in the elemental ratios rather suggestive of similar chemical evolution if not of an unique population. These galaxies are characterized by a moderate, if any, enhancement of α-elements over Fepeak elemental abundance with [S/Zn]≈ 0 and [O/Zn]≈ 0.2, rather similarly to the dwarfs galaxies in the Local Group. Nitrogen shows a peculiar behaviour with a bimodal distribution and possibly two plateaux. In particular, the plateau at low N abundances ([N/H] < -3), is not observed in other atrophysical sites and might be evidence for primary N production by massive stars.
منابع مشابه
NEW DAMPED Lyα METALLICITIES FROM ESI SPECTROSCOPY OF FIVE PALOMAR SKY SURVEY QUASARS
This paper presents chemical abundance measurements for 12 new z > 3 damped Lyα systems discovered toward five quasars from the Palomar Sky Survey. We determine H I column densities from profile fits to the observed damped Lyα profiles and measure ionic column densities and limits for all observed metal-line transitions. This dataset, acquired with the Echellette Spectrograph and Imager on the ...
متن کاملGalactic Chemical Abundances at Z > 3 I: First Results from the Echellette Spectrograph and Imager
We present the first results from an ongoing survey to discover and measure the metallicity of z > 3 damped Lyα systems with the Echellette Spectrograph and Imager (ESI) on the Keck II telescope. Our motivation arises from a recent study on the damped Lyα systems suggesting only mild evolution in the cosmic metallicity from z ∼ 2 to 4. The Echellette Spectrograph and Imager, which provides two ...
متن کاملTHE UCSD HIRES/KECKI DAMPED Lyα ABUNDANCE DATABASE II. THE IMPLICATIONS
We present a comprehensive analysis of the damped Lyα 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, Co, O, and Ar from 38 damped Lyα systems with zabs > 1.5. With little exception, these damped Lyα systems exhibit very similar relative abundances. There is ...
متن کاملChemical Abundances in the Damped Lyα Systems
I introduce and review the data and analysis techniques used to measure abundances in the damped Lyα systems, quasar absorption-line systems associated with galaxies in the early Universe. The observations and issues associated with their abundance analysis are very similar to those of the Milky Way’s interstellar medium. We measure gas-phase abundances and are therefore subject to the effects ...
متن کاملAbundance Patterns of Heavy Elements in Damped Lyman-alpha Galaxies
We present a quantitative analysis of the abundances of heavy elements in damped Lyα galaxies in the sample of Lu et al. (1996). In particular, we compare the observed gas-phase abundances with those expected when the intrinsic (i.e., nucleosynthetic) pattern is the same as that in either the Sun or in Galactic halo stars and when the depletion pattern is the same as that in the warm Galactic i...
متن کاملElemental Abundances at Early Times: the Nature of Damped Lyman-alpha Systems
The distribution of element abundances with redshift in Damped Lyα (DLA) systems can be adequately reproduced by the same model reproducing the halo and disk components of the Milky Way Galaxy at different galactocentric distances: DLA systems are well represented by normal spiral galaxies in their early evolutionary stages.
متن کامل