Kerr polar tortoise coordinate
= Kerr polar tortoise coordinate
{c}
On the Kerr symmetry axis, the radial metric has $F=\Delta/(r^2+a^2)$ and the tortoise coordinate satisfies $dr_*/dr=F^{-1}=(r^2+a^2)/\Delta$.
= Kerr polar tortoise coordinate
{c}
On the Kerr symmetry axis, the radial metric has $F=\Delta/(r^2+a^2)$ and the tortoise coordinate satisfies $dr_*/dr=F^{-1}=(r^2+a^2)/\Delta$.