damped Lyman-alpha systems
E451580
Damped Lyman-alpha systems are high-column-density neutral hydrogen gas clouds observed in quasar spectra, serving as key probes of the interstellar medium and chemical evolution of galaxies in the early universe.
Observed surface forms (1)
| Surface form | Occurrences |
|---|---|
| damped Lyman-alpha system | 0 |
Statements (48)
| Predicate | Object |
|---|---|
| instanceOf |
astrophysical object
ⓘ
neutral hydrogen absorber ⓘ quasar absorption line system ⓘ |
| causes | depletion of refractory elements onto dust grains ⓘ |
| constrains |
cosmic evolution of neutral hydrogen density
ⓘ
nucleosynthesis yields of early generations of stars ⓘ |
| contains | dust ⓘ |
| contrastedWith |
Lyman-alpha forest absorbers
NERFINISHED
ⓘ
Lyman-limit systems NERFINISHED ⓘ |
| definedBy | high-column-density neutral hydrogen gas ⓘ |
| hasAbbreviation | DLA NERFINISHED ⓘ |
| hasAlternativeName | damped Lyα system ⓘ |
| hasCosmologicalSignificance | dominant reservoir of neutral gas at high redshift ⓘ |
| hasEnvironment | often associated with faint or low-luminosity galaxies ⓘ |
| hasKinematics |
multiple narrow velocity components
ⓘ
velocity widths of tens to hundreds of km s^-1 ⓘ |
| hasLowerColumnDensityLimitThan | sub-damped Lyman-alpha systems ⓘ |
| hasLymanAlphaProfile | damped wings ⓘ |
| hasMetallicity |
sub-solar metallicity
ⓘ
typically 1/100 to 1/3 solar ⓘ |
| hasNeutralHydrogenColumnDensity |
> 10^20.3 atoms cm^-2
ⓘ
> 2×10^20 atoms cm^-2 ⓘ |
| hasObservationTechnique | high-resolution optical and UV spectroscopy ⓘ |
| hasOpticalDepth | optically thick at the Lyman limit ⓘ |
| hasPhysicalComponent | neutral hydrogen gas cloud ⓘ |
| hasRedshiftRange | z ~ 0–5 and above ⓘ |
| hasSelectionMethod | absorption-selected in background source spectra ⓘ |
| hasTypicalRedshiftRange | high redshift (z ≳ 2) ⓘ |
| locatedIn |
circumgalactic medium
ⓘ
interstellar medium of galaxies ⓘ |
| measuredBy |
Voigt profile fitting of Lyman-alpha line
ⓘ
curve-of-growth analysis of metal lines ⓘ |
| observedIn |
gamma-ray burst afterglow spectrum
ⓘ
quasar spectrum ⓘ |
| probes |
chemical evolution of galaxies
ⓘ
cosmic neutral gas content ⓘ interstellar medium in high-redshift galaxies ⓘ star-formation fuel in the early universe ⓘ |
| relatedTo | sub-damped Lyman-alpha system ⓘ |
| showsSpectralFeature |
Lyman series absorption lines
ⓘ
damped Lyman-alpha absorption line ⓘ metal absorption lines ⓘ |
| traces | neutral gas reservoir for star formation ⓘ |
| usedAs |
probe of galaxy formation
ⓘ
probe of large-scale structure ⓘ tracer of cosmic metal enrichment ⓘ |
| usedToMeasure |
abundances of elements such as Fe, Si, Zn, S
ⓘ
primordial deuterium abundance in some cases ⓘ |
Referenced by (1)
Full triples — surface form annotated when it differs from this entity's canonical label.
subject surface form:
MIKE