Dirac Equation on Kerr--Newman spacetime and Heun functions

Understand

By employing a pseudo-orthonormal coordinate-free approach, the Dirac equation for particles in the Kerr--Newman spacetime is separated into its radial and angular parts.

• In the massless case to which a special attention is given, the general Heun-type equations turn into their confluent form.
• We show how one recovers some results previously obtained in literature, by other means.