Supervisor: Dr Tim Cawthorne
The jets of active galaxies represent one of the most extreme phenomena in the Universe.
Their role is to transport matter and energy away from their galactic nuclei at speeds
approaching that of light. The unique astrophysical importance of these outflows lies in the fact that they
represent an observable (and resolvable) manifestation of the nuclear activity that also
gives
rise to dramatic continuum variability and excitation of the emission line regions; they also carry magnetic
fields into the extragalactic medium, which may play an important role as seeds for the magnetic fields of
galaxies. In this project the behaviour of one particular system will be examined as monitored over a period of
several years, using the Global Millimetre-wave VLBI Array (GMVA, see
http://www.mpifr-bonn.mpg.de/div/vlbi/globalmm/). These data provide an insight into the
structure of radio jets on the smallest angular scales that can be resolved at present.
The main aim of the project is to investigate features within the jet that have
been inferred indirectly through analyses of lower resolution data, but
can be imaged directly using the new GMVA data. The importance of these
features is that they imply systematic changes in the jet direction on the smallest
scales, suggesting precession or some type of instability of the outflow.
If real, these features may be an important link to the galactic
central engine, and it becomes necessary to understand how they affect the observed structure
of the jet on larger scales. If not real, then we need to understand how the structures
observed at the GMVA gave rise to the lower resolution data. In addition to this work there
is the opportunity to undertake theoretical modelling of jet structures including the effect
of shock waves and magnetic field geometry.
The project will be carried out in collaboration with Dr. Thomas Krichbaum (Max Planck
Institute for Radio Astronomy, Bonn, Germany) and Dr. Denise Gabuzda (University College,
Cork, Ireland.)