On Ionization Effects and Abundance Ratios in Damped Lyα Systems
نویسندگان
چکیده
منابع مشابه
ON IONIZATION EFFECTS AND ABUNDANCE RATIOS IN DAMPED Lyα SYSTEMS
The similarity between observed velocity structures of Al III and singly ionized species in damped Lyα systems (DLAs) suggests the presence of ionized gas in the regions where most metal absorption lines are formed. A simplified model consisting of Region 1) a plane-parallel ionization bounded region illuminated by an internal radiation field, and Region 2) a neutral region with a negligible me...
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Studies of elemental abundances are a fundamental tool for unveiling the nature of the high-redshift (proto-)galaxies associated to Damped Ly α systems (DLAs). The present contribution analyses the impact of dust and ionization effects on abundance measurements in DLAs. The behaviour of the α/Fe abundance ratio corrected for such effects is used to derive information on the chemical history and...
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Observations of damped Lyα systems offer a unique window on the neutral-gas reservoirs that gave rise to galaxies at high redshifts. This review focuses on critical properties such as the H I and metal content of the gas and on independent evidence for star formation. Together, these provide an emerging picture of gravitationally bound objects in which accretion of gas from the IGM replenishes ...
متن کاملOn ionisation effects and abundance ratios in damped Lyman-α systems
The similarity between observed velocity structures of Al III and singly ionised species in damped Lyα systems (DLAs) suggests the presence of ionised gas in the regions where most metal absorption lines are formed. To explore the possible implications of ionisation effects we construct a simplified two-region model for DLAs consisting of an ionisation bounded region with an internal radiation ...
متن کاملBIMODALITY IN DAMPED Lyα SYSTEMS
We report evidence for a bimodality in damped Lyα systems (DLAs). Using [C II] 158 μm cooling rates, lc, we find a distribution with peaks at lc=10 −27.4 and 10 ergs s H separated by a trough at l c ≈ 10 −27.0 ergs s H. We divide the sample into ‘low cool’ DLAs with lc ≤ l crit c and ‘high cool’ DLAs with lc > l crit c and find the Kolmogorv-Smirnov probabilities that velocity width, metallicit...
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ژورنال
عنوان ژورنال: The Astrophysical Journal
سال: 2001
ISSN: 0004-637X,1538-4357
DOI: 10.1086/319429