10676(  1) - 04/05/05 12:32  - [  1]

    PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS   ST ScI Use Only
                                                       ID:      10676
                                                       Version: 1
                                                       Check-in Date: 05-Apr-2005
                                                                      16:32:09

1.Proposal Title:
The HST Archive Galaxy-scale Gravitational Lens Search
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2. Proposal For  3. Cycle  4. Parallel Pointing Tolerance
AR               14        <none>
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5. Investigators
                                                                                     Contact?
    PI: Dr. Philip J. Marshall            Stanford University
   CoI: Prof. Roger D. Blandford          Stanford University                           N
   CoI: Prof. Christopher Fassnacht       University of California - Davis              N
   CoI: Dr. Leonidas Moustakas            Space Telescope Science Institute             N

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6. Abstract

We propose the largest homogeneous space-based optical gravitational lens search
possible prior to the launch of SNAP/JDEM. The HST archive contains a total of 2.2
square degrees of sky imaged with either ACS (78%) or WFPC2 in at least two filters
to an appromximate I-band depth of 25 magnitudes. We estimate (with some
uncertainty) this area to contain approximately 20-30 elliptical-galaxy strong
gravitational lenses, enlarging the currently known sample by some 25%.
Complementing those discovered by other means, this lens sample will enable such
applications as: the detailed study of galaxy dark matter distributions, their
relation to luminous matter, their evolution and their environments; cosmology,
through the measurement of time delays (and so the Hubble constant), and via the
observed lensing rate and image separations which probe volumes and distance ratios
sensitive to the dark energy parameters. The legacy of this survey will also be that
of a suite of automated lens detection algorithms; continuing to refine and apply
these to future ACS images as they are archived will allow the discovered lens
numbers given above to be doubled. Finally, these algorithms will provide the
foundations for the analysis of data from future wide-field space-based optical
imagers, which will repeat this lens survey on three orders of magnitude larger a
scale.
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                                                10676(  1) - 04/05/05 12:32  - [  2]

            Summary Form for Proposal  10676

  Item                         Used in this proposal
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  Proposal Category            AR
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