10954(  1) - 04/03/06 11:08  - [  1]

                  HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 10954

Version: 1    Check-in Time: 03-Apr-2006 15:07:58

Title
Probing the nature and local environments of Ultraluminous X-ray sources
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Type             Cycle     Parallel Pointing Tolerance
AR               15        <none>
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Investigators
                                                                                     Contact?
    PI: Dr. Kajal K. Ghosh                Universities Space Research Association
   CoI: Dr. Roberto Soria                 University College London (UCL)               N
   CoI: Dr. Christopher Copperwheat       University College London (UCL)               N
   CoI: Dr. Doug Swartz                   Universities Space Research Association       N
   CoI: Dr. Allyn Tennant                 NASA Marshall Space Flight Center             N

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Abstract

We have demonstrated that: (1) the positional errors of ULXs between the Chandra and
HST images can be achieved better than 0."2, (2) comparison of colors and magnitudes
with the evolutionary tracks and isochrones can be used to study the starformation
history of the local environments of ULXs, and (3) our irradiation model of the
donor star and accretion disk in ULX binaries will be able to constrain the binary
parameters of ULXs. Based on these techniques, we propose a pilot study to determine
the nature and local environments of thirty ULXs in nearby galaxies, for which high
signal-to-noise ratio HST data with broadest photometric coverage are available in
the archive. Analysis of high-resolution radio and infrared images of most of these
galaxies are in progress, which will be used to search for the counterparts of ULXs
and mainly for the starformation studies of the local environments of ULXs. This
program will strongly support our new Chandra survey of ULXs for distance-limited
complete sample of 147 galaxies, approved in Cycle 7. In addition, the results of
this program will generate large number of sources with multiwavelength properties,
for a complete sample of galaxies, which can be used in future to address many other
challenging issues of astronomy and astrophysics.
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