The Complex North Transition Region of Centaurus A: Radio Structure
  We present deep radio images of the inner 50 kpc of Centaurus A, taken with
the Karl G. Jansky Very Large Array (VLA) at 90cm. We focus on the Transition
Regions between the inner galaxy - including the active nucleus, inner radio
lobes, and star-forming disk - and the outer radio lobes. We detect previously
unknown extended emission around the Inner Lobes, including radio emission from
the star-forming disk. We find that the radio-loud part of the North Transition
Region, known as the North Middle Lobe, is significantly overpressured relative
to the surrounding ISM. We see no evidence for a collimated flow from the
Active Galactic Nucleus (AGN) through this region. Our images show that the
structure identified by Morganti et al. (1999) as a possible large-scale jet
appears to be part of a narrow ridge of emission within the broader, diffuse,
radio-loud region. This knotty radio ridge is coincident with other striking
phenomena: compact X-ray knots, ionized gas filaments, and streams of young
stars. Several short-lived phenomena in the North Transition Region, as well as
the frequent re-energization required by the Outer Lobes, suggest that energy
must be flowing through both Transition Regioins at the present epoch. We
suggest that the energy flow is in the form of a galactic wind.
