A note on the Viability of gaseous ionization in active galaxies by fast shocks

摘要

Morphological and spectroscopic evidence suggests that shocks may affect the spatial and velocity distributions of gas in the narrow-line region(NLR) and the extended NLR of some active galaxies. It thus seemed plausible that shocks may energize the NLR also. The observed emission-line ratios strongly favor photoionization as the heating source for this gas, but it is not clear whether the ionizing radiation is generated in the NLR by "photoionizing shock" or whether the ionizing radiation originates at the central continuum source.