10324(  1) - 04/02/04 12:00  - [  1]

    PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS   ST ScI Use Only
                                                       ID:      10324
                                                       Version: 1
                                                       Check-in Date: 02-Apr-2004
                                                                      12:00:05

1.Proposal Title:
The Morphology of Ly-alpha Emission Galaxies at z=3.11 in the GOODS-S Field
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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. Caryl Gronwall                The Pennsylvania State University
   CoI: Dr. Robin Ciardullo               The Pennsylvania State University             N
   CoI: Dr. John Feldmeier                Case Western Reserve University               N

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6. Abstract

The discovery of large numbers of Lyman-break galaxies has revolutionized our
ability to study the distant universe. Today, narrow-band surveys have finally
caught up and are detecting Ly-alpha emission-line galaxies (ELGs) from z=2.4 to
z=6.5. These are important objects: not only do they sample a part of the galaxy
luminosity function that is inaccessible to the Lyman-break technique, but they also
tend to be younger and less chemically evolved. As a result, these ELGs present us
with a unique opportunity to study galaxies in the process of formation. We have
performed several ground-based narrow-band surveys for ELGs at z~3.1, including one
centered on the Chandra Deep Field South. Spectroscopy has confirmed that our
objects have broad (~450 km/s), asymmetric line profiles, consistent with that of a
starburst galaxy. We propose to use archival HST ACS WFC observations of the Chandra
Deep Field South from the GOODS treasury program to study the morphology of Ly-alpha
ELGs at z=3.11. Our recent ground-based survey of this field contains about 10 Ly-
alpha ELGs within the GOODS ACS WFC pointings. The F775W and F850LP images will
detect the objects' rest-frame UV continuum, and allow us to measure their structure
on sub-kpc scales. With these data we can probe the physical nature of these distant
objects and derive important new insights on the nature of galaxy formation. In
addition, we will directly compare the properties of our ELGs to similar objects
found at higher redshift (4 < z < 7), and to the Lyman-break galaxies contained in
the field. This sample is an important lower redshift counterpart to recent
discoveries of Ly-alpha ELGs at higher redshift (z = 4 - 7). In addition, we will be
able to directly compare the properties of the emission-line sources to Lyman-break
galaxies at the same redshift in the same field discovered by the GOODS team.
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                                                10324(  1) - 04/02/04 12:00  - [  2]

            Summary Form for Proposal  10324

  Item                         Used in this proposal
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  Proposal Category            AR
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