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Testing
the photoionisation models of powerful radio galaxies
Tim Robinson (Sheffield)
Although photoionization has been proposed as the dominant mechanism
of emission line production in powerful radio galaxies, the models
have not yet been tested in depth. Such testing requires good quality
data of an objects in which there is no evidence of jet-induced
shocks. I present high quality spatially resolved observations of one
such object, 3C 321, which allow the line ratios to be accurately
measured, and various diagnostic line ratios to be
plotted. Signal-to-noise is high enough that variations in density,
ionization parameter and temperature may be traced across the object.
These indicate that 3C 321 is an extremely powerful source of
photoionizing photons, with a photoionizing luminosity greater than
that of the powerful quasar 3C 273.
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