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We use a volume- and flux-limited sample of local ($0.03 \leq z \leq 0.1$) radio galaxies with optical counterparts to address the question of how long a typical galaxy spends in radio-active and quiescent states. The length of the active phase has a strong dependence on the stellar mass of the host galaxy. Radio sources in the most massive hosts are also retriggered more frequently. The time spent in the active phase has the same dependence on stellar mass as does the gas cooling rate, suggesting the onset of the quiescent phase is due to fuel depletion. We find radio and emission line AGN activity to be independent, consistent with these corresponding to different accretion states.Comment: accepted for publication in MNRAS; 15 pages, 14 figure

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In previous papers we have discussed high-resolution observations of a large sample of powerful radio galaxies with z < 0.3. Jets are detected in up to 80 per cent of the sample, and radio cores in nearly all the objects; in addition, we are able to resolve the hotspots in most sources. In this paper we present measurements of the radio properties of these components.The prominences of the jets detected do not appear to be a function of radio luminosity, providing the clearest evidence yet that the reported low detection rate of jets in radio galaxies has been an artefact of low-sensitivity observations. We find a positive correlation between the total source length and core prominence in the narrow-line radio galaxies. We have found evidence for a relationship between hotspot size and total source size, but few other significant relationships between hotspot properties and those of the jets or lobes. We compare our measurements with those of Bridle et al., based on observations of a sample of quasars, and argue that the results are consistent with a modification of the unified model in which the broad-line radio galaxies are the low-luminosity counterparts of quasars, although the situation is complicated by contamination with low-excitation radio galaxies which appear to have radio properties different from the high-excitation objects. We discuss the classes of empirical model that can be fitted to the data set.

We present observations made with the VLA at 1.5 and 8.4 GHz of the nearby FRI radio galaxy 3C 296. The most recent models of FRI radio galaxies suggest that substantial deceleration must take place in their jets, with strongly relativistic velocities on parsec scales giving place to at most mildly relativistic velocities on scales of tens of kiloparsecs. The region over which this deceleration takes place is therefore of considerable interest. By considering the side-to-side asymmetries of the jets of 3C 296, we constrain the region of strong deceleration in the source. Our observations show evidence that the jets have slow edges surrounding faster central spines. We discuss the implications of our observations for models of the magnetic field structure in these objects.

In a long‐term observing project we have imaged a complete sample of Fanaroff–Riley II (FRII) quasars and radio galaxies with z < 1.0 at high resolution and high sensitivity with the Very Large Array (VLA) and Multi‐Element Radio‐Linked Interferometer (MERLIN). This sample of 98 sources includes 15 quasars, 11 broad‐line radio galaxies and 57 narrow‐line radio galaxies, allowing unification to be considered in terms of source morphological properties. Radio maps of all the targets have been presented in earlier papers. Here we carry out a systematic analysis of the properties of the jets, cores, lobes and hotspots of objects in the sample. The majority of the tests that we perform show that the data are consistent with a model in which quasars and broad‐line radio galaxies are unified with narrow‐line objects. Relativistic beaming is the main effect that determines the properties of kiloparsec‐scale jets, and it may also have some effect on hotspots. However, some properties of the sample are difficult to account for in simple unified models.

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