Relaxation dynamics of charged gravitational collapse

We study analytically the relaxation dynamics of charged test fields left outside a newly born charged black hole. In particular, we obtain a simple analytic expression for the fundamental quasinormal resonances of near-extremal Reissner-Nordstr"om black holes. The formula is expressed in terms of the black-hole physical parameters: $\omega=q\Phi-i2\pi T_{BH}(n+{1 \over 2})$, where $T_{BH}$ and $\Phi$ are the temperature and electric potential of the black hole, and $q$ is the charge of the field.