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Grazing collision of two black holes

  1. Jan 10, 2012 #1
    Suppose two black holes graze one another in a high speed encounter. The collision is glancing such that the event horizons merge and then separate.

    Q1) I assume this is possible?

    Now suppose that the collision is nearly but not completely collinear.

    Q2) Is it true in this case that each singularity would become entrained in the timelike worldline of the other and they would merge into one singularity?

    Now here's the kicker. Suppose there is a small mass in low orbit around one of the holes in the first case.

    Q3) Is it possible that the orbiting body would find itself enveloped by the swollen horizon during the grazing collision but re-emerge as the holes separated? I would presume not; in which case the question becomes

    Q4) which singularity would the orbiting mass become part of? Can this be answered dynamically or is it somehow indeterminate?
  2. jcsd
  3. Jan 10, 2012 #2
    It is not possible. The merger is possible, but not the seperation. Once one event horizon impinges on the other, you've got 1 bigger BH.
  4. Jan 10, 2012 #3
    Good then. It was bothering me a lot that I could pull two holes apart. That it's not possible makes sense.

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