9527(  1) - 12/06/01 12:38  - [  1]

    PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS   ST ScI Use Only
                                                       ID:      9527
                                                       Version: 1
                                                       Check-in Date: 06-Dec-2001
                                                                      11:45:40

1.Proposal Title:
The distribution of dark matter in cD galaxies with giant arcs: combining kinematic
and lensing tracers
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2. Proposal For  3. Cycle
AR               11
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4. Investigators
                                                                                     Contact?
    PI: Tommaso Treu                      California Institute of Technology
   CoI: Prof.  Richard Ellis              California Institute of Technology            N
   CoI: Dr. Jean-Paul Kneib               Toulouse                                      N
   CoI: Mr. David Sand                    California Institute of Technology            N

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5. Abstract

We propose to develop a powerful method for measuring the shape of the dark matter
halo in the inner region of clusters, thus testing a fundamental prediction of the
Cold Dark Matter paradigm. Specifically, we will identify in the HST archive cD
galaxies with associated giant arcs and measure their extended kinematic profiles
using the Keck telescopes. We have already obtained data for 4 systems (2 newly-
discovered ones) demonstrating the feasibility of the project. The combination of
the two independent constraints from dynamics and lensing on the same objects will
allow us to overcome the degeneracies inherent to each method and thus to reliably
measure the shape of the dark matter halo on 1-100 kpc scales. With this proposal we
seek the necessary funding to: i) perfom a systematic search for arcs in the entire
HST cluster archival data in order to collect a sample of 10-20 objects; ii) develop
methods and software for the joint analysis of the kinematic and lensing
constraints.
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                                                9527(  1) - 12/06/01 12:38  - [  2]

            Summary Form for Proposal  9527

  Item                         Used in this proposal
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  Proposal Category            AR
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