7988(  1) - 04/16/98 14:09  - [  1]

    PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS   ST ScI Use Only
                                                       ID:      7988
                                                       Version: 1
                                                       Check-in Date: 16-Apr-1998
                                                                      14:06:01

1.Proposal Title:
Chemical Evolution of QSOs and Their Host Galaxies
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2. Proposal For  3. Cycle
AR               7
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4. Investigators
                                                                                     Contact?
    PI: Fred Hamann                       University of California, San Diego
   CoI: Vesa Junkkarinen                  University of California, San Diego           N
   CoI: Joseph Shields                    Ohio University                               N

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5. Abstract

Estimates of the heavy-element abundances in QSOs/AGNs can yield important
constraints on star formation and galactic nuclear evolution at high redshifts. Our
own recent studies indicate that QSO metallicities are typically solar or higher,
with a tentative trend for greater metallicities in more luminous objects. The high
metallicities are consistent with the rapid, early-epoch star formation expected in
massive galactic nuclei, while the trend with luminosity might derive from a mass-
metallicity relationship among QSO host galaxies. Further study is now needed to
quantify the observational trends with L and z and test the abundance estimates with
better data and more diagnostics. The broad emission lines are vital for this work
because they can be measured in large QSO/AGN samples. We propose an HST archive
program to compare the broad emission-line properties of z<~ 1 QSOs/AGNs in the HST
database with QSOs at z~ 2, z~ 3 and z>~ 4 in existing high-quality, ground-based
data sets. Our emphasize will be on the abundance issues, but this work will also
naturally address various problems concerning the QSOs themselves, such as (1) the
redshift evolution of their environments, (2) the location, geometry and physical
conditions in the emission- line regions, and (3) the influence of metallicity and
luminosity on the nebular physics in general and on the empirical ``Baldwin effect''
in particular.
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                                                7988(  1) - 04/16/98 14:09  - [  2]

            Summary Form for Proposal  7988

  Item                         Used in this proposal
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  Proposal Category            AR
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