2001MNRAS.327..227T

We present new spectroscopic observations of the southern radio galaxy PKS1549-79 z=0.152FWHM∼1350km/s. Despite the flat-spectrum character of the radio emission from this source, our optical spectra show no sign of the broad permitted lines and non-stellar continuum characteristic of quasar nuclei and broad-line radio galaxies. However, the high-ionization forbidden lines, including [Oiii]λλ5007, 4959, are unusually broad for a narrow-line radio galaxy (FWHM∼650km/s), and are blueshifted by 600km.s^–1 relative to the low-ionization lines such as [Oii]λλ3726,3729. The [Oii] lines are also considerably narrower (FWHM∼650km/s) than the [Oiii] lines, and have a redshift consistent with that of the recently detected Hi 21-cm absorption-line system. Whereas the kinematics of the [Oiii] emission lines are consistent with outflow in an inner narrow-line region, the properties of the [Oii] emission lines suggest that they are emitted by a more extended and quiescent gaseous component. We argue that, given the radio properties of the source, our line of sight is likely to be lying close to the direction of bulk outflow of the radio jets. In this case it is probable that the quasar nucleus is entirely obscured at optical wavelengths by the material responsible for the Hi absorption-line system. The unusually broad [Oiii] emission lines suggest that the radio source is intrinsically compact. Overall, our data are consistent the idea that PKS1549-79 is a radio source in an early stage of evolution.