Active Galaxies
A number of theme members are involved in the study of active galactic nuclei (AGN), particularly radio galaxies, using radio, infra-red, optical, and X-ray techniques. Interests include the environments and dynamics of radio sources, unified models for both high-power and low-power objects, observation and modelling of jets and the X-ray/radio relationship in radio galaxies and quasars. Instruments used by the theme include the VLA, the VLBA, eMERLIN, the ATCA, LOFAR, the HST, Euclid, XMM and Chandra.
Active galaxies can also be used as cosmological probes. Powerful radio sources are markers of massive structures (clusters of galaxies); by observing them at high redshift we can find massive structures in the early universe, which allows us to test models of structure formation, a key goal of cosmology. Once these structures are found, multi-waveband observations are being used to determine key parameters such as mass, dynamical state and baryon content. Radio observations (e.g. of the Sunyaev-Zel'dovich effect), optical (peculiar velocities, weak lensing) and X-ray observations (measurement of the hot intracluster plasma properties) all contribute to these studies.
Figure 1 shows a LOFAR radio image of 3C 83.1B in the Perseus cluster of galaxies, showing the extended radio trail left behind as the galaxy moves at high speed towards the bottom of the image. The large and faint lobe to the left of the bright trail has been revealed for the first time (Bempong-Manful et al.)
Plasma Processes
Many of the observable properties of active galaxies are related to plasma processes in the sources, and these relate to terrestrial fusion plasma physics. Work in the group on particle acceleration and radiation has led to collaborations with the UKAEA fusion physics research group at Culham, and fruitful discussions with long-term professorial visitor A. Thyagaraja.
Working in this area
