Distinguishing Kerr naked singularities and black holes using the spin precession of a test gyro in strong gravitational fields

Understand

We study here the precession of the spin of a test gyroscope attached to a stationary observer in the Kerr spacetime, specifically, to distinguish naked singularity (NS) from black hole (BH).

• It was shown recently that for gyros attached to static observers, their precession frequency became arbitrarily large in the limit of approach to the ergosurface.
• For gyros attached to stationary observers that move with non-zero angular velocity $\Omega$, this divergence at the ergosurface can be avoided.
• Specifically, for such gyros, the precession frequencies diverge on the event horizon of a BH, but are finite and regular for NS everywhere except at the singularity itself.