9195(  1) - 12/20/00 23:38  - [  1]

    PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS   ST ScI Use Only
                                                       ID:      9195
                                                       Version: 1
                                                       Check-in Date: 20-Dec-2000
                                                                      23:30:10

1.Proposal Title:
Transverse Structure in the Lyman Alpha Forest and a Program to Measure the
Cosmological Constant
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2. Proposal For  3. Cycle
AR               10
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4. Investigators
                                                                                     Contact?
    PI: Arlin Crotts                      Columbia University
   CoI: Prof. Lam Hui                     Columbia University                           N
   CoI: Prof. David Tytler                University of California, San Diego           N

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5. Abstract

We propose to combine archival UV HST spectra of close QSO pairs with a large sample
of similar optical spectra in order to determine the clustering strength of
intergalactic H I absorption (the Lyman Alpha forest) with the intent of
constraining hydrodynamic/gravitational models of structure formation in the early
Universe. Furthermore, this dataset will allow a comparison of radial versus
transverse clustering for weak overdensities in the Universe. Since radial versus
transverse size for objects co-expanding with the Hubble flow is an excellent
measure of the cosmological constant Lambda, and since the Lyman Alpha forest is
relatively weakly clustered, the shape of its clustering function in radial versus
transverse dimensions is an excellent prospect for uncovering the value of Lambda.
We would like to fully analyze the close QSO pairs in the archive, including several
that remain unpublished after many years, and combine these with high quality
optical spectra extending blueward to atmospheric cutoff in order to provide study
of Lyman Alpha forest structure that is as free as possible of systematic errors due
to interloping metal lines. Such a study might not only determine Lambda, but lead
to an independent, new measure of the density of normal matter Omega_baryon, the
strength of ionizing radiation flux in the early Universe, and better constraints on
other cosmological parameters open to study after testing numerical models of the
Lyman Alpha forest can be trusted.
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                                                9195(  1) - 12/20/00 23:38  - [  2]

            Summary Form for Proposal  9195

  Item                         Used in this proposal
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  Proposal Category            AR
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