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Non-rotating or rotating Metric

  1. Aug 11, 2013 #1
    Is the Milky Way Galaxy non-rotating or rotating?

    Which metric is best suited: Schwarzschild or the Kerr Metric, respectively?
     
  2. jcsd
  3. Aug 11, 2013 #2

    Dale

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    The galaxy is rotating, but it is not spherically symmetric so neither Kerr nor Schwarzschild is good.
     
  4. Aug 12, 2013 #3

    PAllen

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    It is also matter dominated (matter is spread throughout, rather than vaccuum plus center you can treat as 'black box'). Thus, a rotating, asymmetric dust solution would be required. This requires numerical relativity. Of course, it is adequate, in practice, to use Newtonian gravity with PPN corrections in the galactic center to model galaxy evolution.
     
  5. Aug 12, 2013 #4

    Mentz114

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    There are lots of rotating dust solutions in GR. But as PAllen has said it is good enough to use Newtonian gravity with PPN corrections to model galaxy evolution.

    The most recent rotating metric is probably here arXiv:1003.1453v1,

    BOUNDARY VALUE PROBLEMS FOR THE STATIONARY AXISYMMETRIC EINSTEIN EQUATIONS: A DISK ROTATING AROUND A BLACK HOLE

    JONATAN LENELLS

     
    Last edited: Aug 12, 2013
  6. Aug 12, 2013 #5

    PAllen

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    That's cool, thanks! Maybe better as highly ideal model of a BH with accretion disk rather than a galaxy. Maybe not even that: by definition, an accretion disk is not stationary (BH is growing), and no real system has perfect symmetry. Thus, investigations into GW produced BH-stellar interactions where the start gets eaten (with lots of matter ejected as well), all use numeric relativity.
     
  7. Aug 12, 2013 #6

    Mentz114

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    Yes, it's a shame that so many commonplace physical scenarios are difficult ( or imposible ?) to model with GR. Is there a book on numerical relativity you can recommend ?
     
  8. Aug 12, 2013 #7

    PAllen

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    No, but the following web site links to a whole series of papers describing their methods:

    www.black-holes.org

    see specifically:

    http://www.black-holes.org/numrel1.html
    http://www.black-holes.org/numrel2.html // 3,4 etc.
    http://www.black-holes.org/SpEC.html
    http://www.black-holes.org/researchers3.html
    http://www.black-holes.org/researchers1.html
     
  9. Aug 12, 2013 #8

    Mentz114

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    I've had a quick look and it does look interesting. Thank you.
     
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