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The ultraviolet absorption spectrum of the quasar PKS 0405-12 and the local density of Lyman-alpha absorption systemsA sample of 32 absorption lines has been identified in the ultraviolet spectrum of the z = 0.57 quasar PKS 0405-12. Data cover the wavelength range 1190-3260 A. There are 10 extragalactic Ly-alpha absorption lines in the complete sample, all with observed equivalent widths greater than or equal to 0.40 A; three of the Ly-alpha lines have Ly-beta counterparts. The number of Ly-alpha lines observed in the spectrum of PKS 0405-12 is within 1 sigma of the number predicted on the basis of previous HST observations of 3C 273 and of H1821 + 643. Combining the HST observations of 3C 273, H1821 + 643, and PKS 0405-12, we estimate the local number density of Ly-alpha systems with rest equivalent widths larger than 0.32 A to be about 15 +/- 4 Ly-alpha lines per unit redshift. Ground-based images reveal a rich field of galaxies in the direction of PKS 0405-12, including many galaxies with the brightnesses and sizes expected if they belong to a cluster associated with the quasar. The quasar spectrum does not show any evidence for absorption at the redshift of the emission lines, indicating a covering factor of less than unity for the halos of galaxies in the cluster around PKS 0405 - 12.
Document ID
19930046713
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Bahcall, John N.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Jannuzi, Buell T.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Schneider, Donald P.
(Inst. for Advanced Study Princeton, NJ, United States)
Hartig, George F.
(Space Telescope Science Inst. Baltimore, MD, United States)
Date Acquired
August 16, 2013
Publication Date
March 10, 1993
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 405
Issue: 2
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
93A30710
Funding Number(s)
CONTRACT_GRANT: NAS5-26555
CONTRACT_GRANT: NAG5-1618
Distribution Limits
Public
Copyright
Other

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