MG13 - Talk detail |
Participant |
Åman, Jan | |||||||
Institution |
Fysikum, Stockholm University - AlbaNova University Center - Stockholm - - Sweden | |||||||
Session |
BH3 |
Accepted |
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Order |
Time |
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Talk |
Oral abstract |
Title |
Velocity-of-light surfaces in Kerr and extreme Kerr | |||||
Co-authors | ||||||||
Abstract |
The Kerr solution possesses two linearly independent Killing vector fields, $\partial_t$ and $\partial_\phi$, linear combinations of them are also Killing vectors. The linear combination $\partial_{t} +\frac{a}{2m r_+}\partial_{\phi}$ is known to be null at the event horizon $r = r_+$. But there are other hypersurfaces where it goes null. In the Kerr case one such surface surrounds the event horizon while in the extreme case it crosses it. In the extreme case there is a region around the equator where the horizon Killing vector is spacelike on both sides of the event horizon. We have investigated how the behavior in the extreme case can be understood as a limiting case. For near extreme Kerr we can see that those hypersurfaces continuously approach the hypersurface for extreme Kerr. |
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