S. W. Unger

Radio lobes and forbidden O III profile substructure in Seyfert galaxies

High spatial and spectral resolution observations are presented for 10 Seyfert galaxies in the H-beta-forbidden O III 5007 A spectral region. In most of the objects, there is evidence for forbidden O III profile substructure, which appears to be most conspicuous close to the location of a radio lobe. The relative intensities of forbidden O III component emission and ambient forbidden O III emission vary greatly from object to object. A control sample shows little evidence for spatially resolved forbidden O III profile substructure. The forbidden O III components usually have high excitation. The component velocities can fall well outside the maximum galactic rotation amplitude and, in some cases, are opposite to the sense of rotation. This strongly suggests that the component gas does not rotate with the rest of the galactic gas but is instead undergoing systematic outflow. 47 references.

High Velocity Resolution Observations of the ISM in NGC 4151

We have used the Utrecht Echelle Spectrograph to obtain high velocity resolution (6 kms−1) observations of the extended narrow line region in the Seyfert nucleus of NGC4151. We compare the velocity structure of the ionised gas with neutral hydrogen observations and confirm that the photoionisation of quiescent ambient gas is the prefered mechanism to account for the extended region of ionised gas associated with this source. We observe line-splitting in the ENLR of NGC4151 which is consistent with gas associated with an ionisation front expanding outwards from the ENLR.

The morphology of Sersic-Pastoriza galaxies

The authors present the preliminary results of their radio-continuum and neutral hydrogen observations of Sersic-Pastoriza (S-P) galaxies. They show that the central regions contain a population of compact features thought to be young supernova remnants (SNRs) and discuss the overall morphology of the nuclei.

The interaction of radio jets with the narrow line region in Seyfert galaxies

Long-slit spectroscopic observations of Seyfert galaxies reveal sub-structure in the [OIII] λ5007 emission-line profile. The sub-structure is spatially resolved and located close to the position of the near-nuclear radio lobes. The velocity of the sub-structure emission is quite different from galactic rotation and almost certainly involves radial outflow. The emission probably originates either in the post-shock region of the radio lobe or from entrained gas in the jet itself. It is not yet clear why some Seyferts have conspicuous [OIII] profile sub-structure while others do not. However, it seems likely that the detailed association of radio and line-emitting gas is at least partly responsible for the well known correlations between ‘global’ radio and emission-line properties.

[0III]-line emission associated with nuclear radio components in Seyfert galaxies

Abstract Close correlations between [0III] emission features and radio components have been found in a project of high resolution long-slit spectroscopy of Seyfert galaxies with linear radio structures in their nuclei. Substructures in the [0III] line profiles can, in several cases, be associated with individual radio components, within the Narrow Line Region. The observed properties of these [0III] features suggest that gas behind the bow shock of an outmoving radio plasmon has cooled and then is photoionized by the central continuum source. About half of the objects studied possess an Extended Narrow Line Region which could be interstellar gas, photoionized by energetic radiation from the nucleus, beamed along the axis of the (jet-like) radio structure.

An Arcsecond Radio Jet in NGC1275 (Perseus A)

We present λ73 cm radio continuum observations of NGC 1275 with an angular resolution of 1.2 arcseconds. The observations show an unresolved core together with two weaker knots which are consistent with a radio jet in position angle ~ 160°. This jet may be associated with an optical filament in PA 172° which aligns precisely with the λ2.8 cm VLBI jet and shows an unusually high velocity gradient.