10296(  1) - 04/02/04 11:17  - [  1]

    PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS   ST ScI Use Only
                                                       ID:      10296
                                                       Version: 1
                                                       Check-in Date: 02-Apr-2004
                                                                      11:17:03

1.Proposal Title:
Searching for Quasar-Intrinsic Absorption Through Time Variability
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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. Rajib Ganguly                 Space Telescope Science Institute
   CoI: Ms. Melanie Hawthorn              University College London (UCL)               N
   CoI: Dr. Kenneth Sembach               Space Telescope Science Institute             N
   CoI: Prof. Jane C. Charlton            The Pennsylvania State University             N
   CoI: Prof. Michael Eracleous           The Pennsylvania State University             N

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6. Abstract

We propose to use multi-epoch, low-resolution spectra of quasars from the HST
archive to look for narrow absorption lines that exhibit time variability. This is
an economical test for identifying absorbers that are intrinsic to the quasar
central engine, and also provides constraints on the density an/or location of the
gas. Narrow absorption lines (NALs) which appear in the spectra of quasars are very
powerful tool to diagnose the physical conditions (e.g., ionization, geometry) from
a variety of structures, ranging from the ISM of the Galaxy, to the central engine
of the quasar. The primary signatures that distinguish intrinsic NALs from
intervening NALs are partial coverage of the background source and time variability.
The former requires high spectral resolution which can be observationally expensive.
We have completed a pilot study using associated NALs (those which appear near the
quasar redshift) and have devised an approach to efficiently select time-variable
absorption using multi-epoch spectra from different instruments. We wish to expand
our search to the ~100 quasars that have archived multi-epoch low-resolution
spectra. The quasars span a large range of redshifts and luminosity, and the
proposed study will allow us to select low- and high-velocity intrinsic NALs.
Furthermore, we can decipher the underlying cause of the variability - bulk motion
of the gas, or ionization changes - which have differing observational signatures.
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                                                10296(  1) - 04/02/04 11:17  - [  2]

            Summary Form for Proposal  10296

  Item                         Used in this proposal
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  Proposal Category            AR
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