9513(  1) - 12/06/01 12:27  - [  1]

    PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS   ST ScI Use Only
                                                       ID:      9513
                                                       Version: 1
                                                       Check-in Date: 06-Dec-2001
                                                                      11:42:49

1.Proposal Title:
``Binary'' galactic nuclei and binary black holes
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2. Proposal For  3. Cycle
AR               11
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4. Investigators
                                                                                     Contact?
    PI: Scott Tremaine                    Princeton University Observatory

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5. Abstract

We propose to investigate two dynamical problems associated with black holes in
galaxy centers. (1) The nucleus of the nearby galaxy M31 hosts a massive dark
object, probably a black hole, of mass ~ 3*10^7Msun. The M31 nucleus is binary, as
are the nuclei of other galaxies such as NGC 4486B. It is likely that these
``binary'' nuclei actually consist of a high-inclination stellar disk or ring, whose
ansae appear double at low resolution. We shall construct a dynamical model of the
nucleus of M31, which can be fit to two-dimensional HST photometry and extensive HST
and ground-based spectroscopic measurements of the kinematics. The code can also be
used to model other disks found by HST in galaxy centers. (2) Mergers of galaxies
containing black holes lead to the formation of binary black holes. The detection of
such objects would probe the galaxy formation and evolution process, and could
reveal unique new physical phenomena. However, there is considerable uncertainty
whether binary black holes can survive the dissipative processes (mainly dynamical
friction and gravitational radiation) that lead to their orbital decay. We shall
model the evolution of binary black holes in an HST- selected sample of nearby
galaxies, including the critical effects of oblateness and triaxiality on the rate
of refilling the loss cone, and predict how the properties of surviving binary black
holes depend on their host galaxies.
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                                                9513(  1) - 12/06/01 12:27  - [  2]

            Summary Form for Proposal  9513

  Item                         Used in this proposal
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  Proposal Category            AR
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