NRAO/Socorro Colloquium Series:
7 December 1995
Greg Taylor
NRAO/Socorro
The Environment and Evolution
of
Powerful Radio Galaxies
The flux-limited VLBI survey of Pearson & Readhead (1988, ApJ 328,
114), along with the First Caltech--Jodrell Bank Survey (Polatidis et
al 1995, ApJS 98, 1) and Second Caltech--Jodrell Bank Survey (Taylor et
al 1994, ApJS 95, 345) have yielded 34 objects of size < 1 kpc with
emission on both sides of the central engine. These Compact Symmetric
Objects (CSOs) thus comprise 5-10% of all high luminosity AGN. I
will review the current status of multi-frequency, multi-epoch VLBI
observations of the CSOs, and demonstrate that in contrast to nuclear
radio sources in other powerful objects, the observed structure of CSOs
is not dominated by relativistic beaming effects, but instead by
interactions with the surrounding medium. Pressure equilibrium
arguments can then be used to estimate the density of this medium. We
find that the CSOs are young objects which are likely to be the
precursors of the large classical Fanaroff-Riley Type II sources like
Cygnus A. Furthermore, observations of bi-directional jet motions in CSOs
can be used to place restrictions on the distance to the radio source, and
thereby directly constrain H0.
THURSDAY, 7 December 1995
11:00am
Array Operations Center Auditorium
Local Host: Michael Rupen
Other NRAO/Socorro colloquia
mrupen@nrao.edu