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Old 16-08-2010, 12:55 PM
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sjastro
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Quote:
Originally Posted by renormalised View Post
So far you're on the money....the frame dragging effect is only a localised phenomenon around the vicinity of the central supermassive BH, and despite the very large mass of the hole, spacetime gradient for such a large hole is actually rather small (because of its size). If it were a smaller stellar mass hole, the frame dragging effects would be very pronounced (very steep and intense spacetime gradient), but even more localised. On the scale of a galaxy and its arms, the frame dragging can be ignored.
The key is the radius of the erosphere and the event horizon which is a function of BH mass. Increasing BH mass increases the radii. The further the horizons are from the centre of the BH the less the effects of tidal forces and space-time curvature.

Supermassive BHs are pussycats, it's those small solar mass BHs one has to be very careful of.

Steven
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