9545(  1) - 12/06/01 12:49  - [  1]

    PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS   ST ScI Use Only
                                                       ID:      9545
                                                       Version: 1
                                                       Check-in Date: 06-Dec-2001
                                                                      11:50:23

1.Proposal Title:
Understanding Intermediate-luminosity X- ray Objects and their Environments
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2. Proposal For  3. Cycle
AR               11
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4. Investigators
                                                                                     Contact?
    PI: Andrew Ptak                       The Johns Hopkins University
   CoI: Dr. Edward Colbert                The Johns Hopkins University                  N
   CoI: Prof. Tim Heckman                 The Johns Hopkins University                  N
   CoI: Dr. Roeland van der Marel         Space Telescope Science Institute             N

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5. Abstract

X-ray observations of normal galaxies with ROSAT, ASCA and Chandra have revealed
that off-nuclear, compact, Intermediate- luminosity (L_X sim10^39-40 erg/s) X-ray
Objects (IXOs) are quite common. On average, we find that 1 in every 5 galaxies
contains one of these intriguing objects, based on our ROSAT HRI catalog, which is
the most complete IXO catalog yet known. IXOs have received wide attention as
putative intermediate- mass black holes with masses ~10^2-10^5 M_\odot, which would
be quite interesting and puzzling. It is also possible that IXOs are ``ordinary'' X-
ray binaries with stellar-mass black holes, and their X-ray emission is mildly
beamed. Otherwise, little is known about the geometrical and physical properties of
this exciting new class of astrophysical objects. X-ray observations of IXOs alone
have not been able to provide good diagnostics. Deep, high spatial resolution
optical imaging observations can provide important clues to their nature by
examining the environment around the accreting black hole. We request funding to
analyze 267 HST archival images for 38 IXOs from our catalog in order to search for
individual stellar companions and star clusters that may be associated with IXOs,
and to generally identify the nature of the regions harboring IXOs. This AR proposal
is a companion to a SNAP proposal by PI Colbert, which proposes to image IXOs for
which no HST imaging exists yet.
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                                                9545(  1) - 12/06/01 12:49  - [  2]

            Summary Form for Proposal  9545

  Item                         Used in this proposal
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  Proposal Category            AR
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