Discovery of z = 0.0912 and z = 0.2212 Damped Lyα Absorption-Line Systems Toward the Quasar OI 363: Limits on the Nature of Damped Lyα Galaxies
Abstract
The discovery of a zabs=0.0912 damped Lyα absorption-line system in the Hubble Space Telescope Faint Object Spectrograph ultraviolet spectrum of the quasar OI 363 (0738+313) is reported. This is the lowest redshift quasar-damped Lyα system known. Its neutral hydrogen column density is N(H I) =1.5+/-0.2×1021 atoms cm-2, which easily exceeds the classical criterion for damped Lyα of N(H I) >=2×1020 atoms cm-2. Remarkably, a zabs=0.2212 damped system with N(H I) =7.9+/-1.4×1020 atoms cm-2 has also been discovered in the same spectrum.
In the past, the standard paradigm for damped Lyα systems has been that they arise in galactic or protogalactic H I disks with low impact parameters in luminous galaxies. However, WIYN imaging of the OI 363 field shows that none of the galaxies visible in the vicinity of the quasar is a luminous gas-rich spiral with low impact parameter, either at z=0.0912 or z=0.2212. Thus, these damped systems are among the clearest examples yet of cases that are inconsistent with the standard damped Lyα-H I-disk paradigm. Based on data obtained with the NASA/ESA Hubble Space Telescope at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555, and on observations made with the KPNO WIYN telescope, National Optical Astronomy Observatories, operated by AURA, Inc., under cooperative agreement with the National Science Foundation.- Publication:
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The Astrophysical Journal
- Pub Date:
- June 1998
- DOI:
- 10.1086/311411
- arXiv:
- arXiv:astro-ph/9805093
- Bibcode:
- 1998ApJ...500L.115R
- Keywords:
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- GALAXIES: QUASARS: ABSORPTION LINES;
- GALAXIES: QUASARS: INDIVIDUAL ALPHANUMERIC: OI 363;
- GALAXIES: FORMATION;
- Galaxies: Formation;
- Galaxies: Quasars: Absorption Lines;
- Galaxies: Quasars: Individual: Alphanumeric: OI 363;
- Astrophysics
- E-Print:
- to be published in Astrophysical Journal Letters