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キーワード:
General Relativity and Quantum Cosmology, gr-qc,Mathematical Physics, math-ph,Mathematics, Mathematical Physics, math.MP
要旨:
We consider null geodesics in the domain of outer communication of a
sub-extremal Kerr spacetime. We show, that most fundamental properties of null
geodesics can be represented in one plot. In particular one can see immediately
that the ergoregion and trapping are separated in phase space. Furthermore we
show that from the point of view of any timelike observer outside of a black
hole, trapping can be understood as a smooth set of spacelike directions on the
observers' celestial sphere.
