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Q: Galaxy Rotation Curve

  1. Sep 11, 2009 #1

    Hepth

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    Do any of you know which article(s) are used to do the "expected" rotation curve for galaxies, that always seem to be used to compare with data for calculating the distribution of dark matter?
    I'm just trying to find which authors have worked out a published result for the theoretical predictions. I assume there are one or two "major" ones that everyone references.
     
  2. jcsd
  3. Sep 12, 2009 #2

    Bobbywhy

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    Hepth, for a great overview of how galaxy rotation curves are both calculated and measured see:

    arXiv:astro-ph/0010594

    Vera Rubin is one of the two authors, and she is considered one of the pioneers in this field.
    Cheers,
    Bobbywhy
     
  4. Sep 14, 2009 #3

    Hepth

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    I read through that and while it answers some questions about density profiling (polytrpoic indices from exp, etc) the majority of the paper is references! hehe, its pretty hard to dig through actually.

    The author you mentioned is also more of an experimentalist. Or rather doing theory on physical observables.

    I'm looking for something more rigorous, like GR calculations/approximations for various density distributions with different metrics.

    Thanks!
     
  5. Sep 14, 2009 #4

    Bobbywhy

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    I suggest you try going to the arXiv page and typing in your query. For example, I entered "rotation curves general relativity" and got 353 different papers! A more refined search there may help you in your quest.
     
  6. Sep 15, 2009 #5
    Hepth, no one worries about GR when calculating rotation curves of galaxies. The only time people worry about GR is when they are doing calculations for stuff near a compact object (i.e. black hole, neutron star, white dwarf).
     
  7. Sep 15, 2009 #6

    Hepth

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    Well, part of my reasoning for looking for the paper was wondering what is the next order approx from GR over newtonian. And what about things like LL coupling (frame dragging, etc). I know they all have to be VERY small compared to leading order, but i was just curious.
     
  8. Sep 16, 2009 #7

    Bobbywhy

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    Hepth, higher order effects, although small, may play an important role in galactic dynamics. Frame dragging (now verified thanks to the GP-B experiment) is a factor especially on galactic scales. Does the non-Euclidean geometry of a rotating disc affect the perceived location of the emitters? Does the time dilation towards the periphery affect the received frequencies?

    The fact that GR and SR have not been considered in determining rotation curves means the “Dark Matter” problem may continue to be shrouded in mystery. I urge you to continue your research.
     
  9. Sep 16, 2009 #8

    Hepth

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    Well, GR isn't my area of research, I'm high energy theory. Which is why, before wasting my time doing it myself (tedious for someone unpracticed), I was looking for anyone that has done a complete analysis.

    I'm sure the complexities of a locally dynamic metric, coupled with unknown density profiles, causes a lot of headaches in determining things to higher orders.
    I guess I'll just read up more so that exactly what I'm searching for becomes more focused.
     
  10. Sep 16, 2009 #9

    Hepth

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  11. Sep 16, 2009 #10

    Chronos

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    Hepth, I think we can safely rule out time dilation. bombardil is on the right track. MOND is not a good option, if that is where you are going with this.
     
  12. Sep 16, 2009 #11

    Hepth

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    I didn't suggest time dilation, and MOND, haha no. I'm not into fancy new theories that throw out proven concepts in favor of modifying classical ones.

    I'm just trying to learn the pure, simple, as complete as can be, general relativistic approach to the velocity distribution curves. GR is more than just a next order radial approximation to newton, and I wanted to see, at what scales for galaxies does things like angular flow/ "classical spin"/ coupling to the galaxy rotation, etc for a test star come into play.
     
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