AAS 201st Meeting, January, 2003
Session 79. Intergalactic Material: Its Structure and Composition
Poster, Wednesday, January 8, 2003, 9:20am-6:30pm, Exhibit Hall AB

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[79.06] The Sizes of HI Regions Giving Rise to Quasar Damped Lyman-Alpha Absorption Systems

E.M. Monier (The Ohio State University), D.A. Turnshek, S.M. Rao (University of Pittsburgh)

Spectroscopy of quasars along closely-spaced sight-lines can be used to place constraints on the transverse sizes of the foreground regions giving rise to absorption lines seen in the spectra. Of particular interest are the sizes of the HI regions responsible for damped Lyman-alpha (DLA) systems, which have neutral hydrogen column densities exceeding 2 x 1020 atoms cm-2. DLAs are known to track the bulk of the neutral gas in the Universe at redshifts z<3.5. Observing common absorption at DLA column densities generally requires very closely-spaced sight-lines which, for example, are found in gravitationally-lensed quasars. Here we report some of our recent results on DLA region sizes derived using this method and based on observations made with the Hubble Space Telescope. Support for this work was provided by NASA through a grant from STScI, which is operated by AURA under NASA contract NAS 5-26555.

The author(s) of this abstract have provided an email address for comments about the abstract: monier@astronomy.ohio-state.edu

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