10300(  1) - 04/02/04 11:23  - [  1]

    PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS   ST ScI Use Only
                                                       ID:      10300
                                                       Version: 1
                                                       Check-in Date: 02-Apr-2004
                                                                      11:23:08

1.Proposal Title:
Properties of moderate-redshift galaxy groups associated with gravitational lenses
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2. Proposal For  3. Cycle  4. Parallel Pointing Tolerance
AR               13        <none>
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5. Investigators
                                                                                     Contact?
    PI: Prof. Christopher Fassnacht       University of California - Davis
   CoI: Prof. Lori M. Lubin               University of California - Davis              N
   CoI: Dr. John S. Mulchaey              Carnegie Institution of Washington            N
   CoI: Dr. John P. McKean                University of California - Davis              N

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6. Abstract

Strong evidence indicates that the primary lensing galaxies in many gravitational
lens systems are associated with compact groups. We are taking advantage of this
association to conduct an active ground-based program to find galaxy groups at
moderate redshifts. Because the lens galaxies are typically in the redshift range of
0.3<z<1.0, we can use the lenses to find groups at redshifts at which most other
group-search methods are no longer feasible. Our ground-based wide-area (10'x10')
multicolor images, obtained at Palomar and Keck, are used to select targets for
spectroscopy. We have an ongoing spectroscopic follow-up program at Keck and have
spectroscopically confirmed three new lens-associated groups. We have already
obtained spectroscopic data on five additional lens fields, and have been granted
two Keck nights this semester to observe ~5 more fields. Our ground-based imaging
covers 21 lens fields in total. We are proposing to combine the extensive database
of HST images of lens fields with our existing ground-based data. The HST data will
allow us to determine the morphological composition of the members of these
moderate-redshift groups, to study how the galaxy population has evolved with time,
to search for direct evidence of galaxy-galaxy mergers and interactions, and to
compare galaxy evolution in groups and rich clusters.
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                                                10300(  1) - 04/02/04 11:23  - [  2]

            Summary Form for Proposal  10300

  Item                         Used in this proposal
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  Proposal Category            AR
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