Extreme CII emission in type 2 quasars at z~2.5: a signature of
  kappa-distributed electron energies?
  We investigate the flux ratio between the 1335 A and 2326 A lines of singly
ionized carbon in the extended narrow line regions of type 2 quasars at z~2.5.
We find the observed CII 1335 / CII] 2326 flux ratio, which is not sensitive to
the C/H abundance ratio, to be often several times higher than predicted by the
canonical AGN photoionization models that use solar metallicity and a
Maxwell-Boltzmann electron energy distribution. We study several potential
solutions for this discrepancy: low gas metallicity, shock ionization,
continuum fluorescence, and kappa-distributed electron energies. Although we
cannot definitively distinguish between several of the proposed solutions, we
argue that a kappa distribution gives the more natural explanation. We also
provide a grid of AGN photoionization models using kappa-distributed electron
energies.
