10302(  1) - 04/02/04 11:26  - [  1]

    PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS   ST ScI Use Only
                                                       ID:      10302
                                                       Version: 1
                                                       Check-in Date: 02-Apr-2004
                                                                      11:25:59

1.Proposal Title:
PROBING THE NATURE OF DARK MATTER USING CLUSTER LENSING
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2. Proposal For  3. Cycle  4. Parallel Pointing Tolerance
AR               13        <none>
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5. Investigators
                                                                                     Contact?
    PI: Dr. Priyamvada Natarajan          Yale University

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6. Abstract

The detection of gravitational lensing of distant galaxies by foreground galaxies
has been used in recent years to set constraints on the masses and sizes of the
galaxy halos. The same technique has been successfully applied to galaxies in the
dense environments of massive X-ray clusters. These studies point to a smaller
spatial extent for the dark matter halos of cluster galaxies compared to equivalent
luminosity field galaxies due to tidal truncation inside a cluster . The size
distribution of these tidally truncated radii can be used to probe the nature of
dark matter composing these halos by making assumptions about the dynamics and
detailed shape of the gravitational potential of the cluster. The use of simplifying
theoretical assumptions have enabled placing conservative upper limits on the cross-
section for fluid-like dark matter (FDM). The goal of this project is to develop a
more robust theoretical framework utilizing cluster models derived from cosmological
N-body simulations that will provide stronger constraints on the nature and
interaction cross-section of dark matter. This technique when bolstered with
numerical models of clusters offers a unique and complementary way to constrain the
equation of state of DM, and constrain the parameter space of viable candidates.
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                                                10302(  1) - 04/02/04 11:26  - [  2]

            Summary Form for Proposal  10302

  Item                         Used in this proposal
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  Proposal Category            AR
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