Exact solutions for black holes with a smooth quantum core

A class of exact solutions are presented for the interior of black holes of solar mass and beyond. In a core enclosed by the inner horizon, the binding energy released by dissolution of the pre-collapse nuclei is stored in electrostatic and zero point energy. Gravitational collapse is prevented by their negative pressures. In the mantle, the region between the inner and event horizons, there is a standard vacuum. Accounting for the rest masses of the up and down quarks and electrons leads to corrections at the per cent level. Spherically symmetric fluctuations have a spectrum without unstable modes. A surface layer with a charge current can be present on the outer side of the inner horizon; a layer of opposite charges on the event horizon can make an extremely charged black hole neutral. Merging of an extremal black hole with another extremal one or with a neutron star may produce electromagnetic fireworks.