Two-temperature coronae in active galactic nuclei

We show that coronal magnetic dissipation in thin active sheets that sandwich standard thin accretion discs in active galactic nuclei may account for canonical electron temperatures of a few x10(9)K if protons acquire most of the dissipated energy. Coulomb collisions transfer energy from the ions to the electrons, which subsequently cool rapidly by inverse Compton scattering. In equilibrium, the proton energy density probably exceeds that of the magnetic field and both well exceed the electron and photon energy densities. Coulomb energy transfer from protons to electrons is fast enough to explain the observed rapid X-ray variability in Seyfert galaxies. The similar to 10(9)-K electron temperature is insensitive to the proton temperature when the latter is greater than or equal to 10(12)K.