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| Damped Lyman-alpha system | |
|---|---|
| Name | Damped Lyman-alpha system |
| Type | Absorption system |
| Discovered | 1970s |
| Wavelength | Lyman-alpha (1215.67 Å) |
| Significance | High neutral hydrogen column density |
Damped Lyman-alpha system is a class of high-column-density hydrogen absorbers seen in quasar spectra that trace neutral gas reservoirs in the high-redshift Universe. They are important for studies of Quasar, Hubble Space Telescope, Sloan Digital Sky Survey, Keck Observatory, and Very Large Telescope programs that probe baryons, metals, and galaxy progenitors across cosmic time. Damped Lyman-alpha systems provide empirical constraints used by teams at Max Planck Institute for Astronomy, Harvard-Smithsonian Center for Astrophysics, California Institute of Technology, and University of Cambridge.
Damped Lyman-alpha absorbers were first identified in spectra obtained by observers associated with projects using facilities such as Palomar Observatory, Arecibo Observatory, and early International Ultraviolet Explorer campaigns. These systems are characterized by wide, saturated absorption at the Lyman-alpha transition of hydrogen, requiring interpretation by researchers affiliated with Columbia University, Princeton University, University of California, Berkeley, and instruments developed at Jet Propulsion Laboratory. Surveys by collaborations linked to European Southern Observatory and the Anglo-Australian Observatory established their cosmological incidence and connection to high-redshift structure.
Damped Lyman-alpha systems are identified in the spectra of background sources like Seyfert galaxy nuclei, BL Lacertae objects, and bright Quasars observed by spectrographs on Keck Observatory (HIRES), Very Large Telescope (UVES), and Subaru Telescope (HDS). Typical observations report neutral hydrogen column densities in excess of 2×10^20 cm^-2, metal-line transitions from ions associated with elements studied at European Southern Observatory, and kinematic profiles compared with rotation curves measured at Atacama Large Millimeter/submillimeter Array and emission-line studies from James Webb Space Telescope. Teams from Space Telescope Science Institute and National Optical Astronomy Observatory analyzed damping wings, velocity width distributions, and incidence per unit redshift to relate DLAs to surveys such as Sloan Digital Sky Survey and targeted follow-ups at Magellan Telescopes.
The neutral gas in these absorbers shows abundances of elements like silicon, iron, zinc, and sulfur measured by collaborations at Institute for Astronomy, University of Hawaii, Kavli Institute for Cosmology, and Max Planck Institute for Astrophysics. Dust depletion signatures require cross-comparison with extinction studies from WISE, Spitzer Space Telescope, and Herschel Space Observatory. Molecular detections such as H2 or CO have been reported in works involving Green Bank Telescope teams and observers at Institut d’Astrophysique de Paris, constraining physical conditions (temperature, density) in analogy to interstellar medium studies by groups at Carnegie Institution for Science and National Radio Astronomy Observatory.
Models for the origin and evolution of these absorbers are developed by theorists at Institute for Advanced Study, CITA, Princeton University, and University of Oxford, incorporating processes studied in simulations by the Illustris and EAGLE collaborations. Scenarios include gas inflow along filaments connected to Large-scale structure (cosmology), cooling in dark matter halos characterized in work from Los Alamos National Laboratory and Lawrence Berkeley National Laboratory, and feedback from stellar populations associated with Hubble Space Telescope imaging of Lyman-break galaxies. Evolution of metallicity and neutral fraction across redshift is compared to results from teams at European Southern Observatory and Sloan Digital Sky Survey to infer chemical enrichment histories.
Damped Lyman-alpha absorbers serve as reservoirs for star formation in models calibrated by groups at Max Planck Institute for Astrophysics and Harvard-Smithsonian Center for Astrophysics. Their neutral gas mass density measurements are matched to cosmic star-formation histories reported by researchers at Space Telescope Science Institute, NASA, and European Southern Observatory. Constraints from DLAs are used to test predictions of Lambda Cold Dark Matter cosmology developed by collaborations at Stanford University and Cambridge University and inform reionization-era studies undertaken by teams using James Webb Space Telescope and Planck (spacecraft) data.
Detection relies on high-resolution spectroscopy from instruments associated with Keck Observatory, Very Large Telescope, Subaru Telescope, and fiber surveys like Sloan Digital Sky Survey and Dark Energy Survey. Automated search algorithms were developed by groups at University of Cambridge, Carnegie Mellon University, and Yale University to mine databases from Sloan Digital Sky Survey and targeted campaigns with Magellan Telescopes. Follow-up imaging and integral-field spectroscopy by teams at European Southern Observatory and W. M. Keck Observatory aim to identify host galaxies via emission lines in programs led by investigators at California Institute of Technology and National Astronomical Observatory of Japan.
Numerical approaches by the Illustris, EAGLE, and FIRE projects incorporate feedback and cooling processes modeled by researchers at Princeton University, Harvard University, and University of California, Santa Cruz. Radiative transfer calculations from groups at Max Planck Institute for Astrophysics and CITA simulate Lyman-alpha line profiles, while semi-analytic models from teams at Stanford University and Durham University predict incidence rates and metallicity evolution. Comparisons between synthetic absorption spectra and observations from Keck Observatory and Very Large Telescope inform models used by consortia at European Southern Observatory and Space Telescope Science Institute.