New constraints on the structure and dynamics of black hole jets
  Accreting black holes produce powerful relativistic plasma jets which emit
radiation across all observable wavelengths but the details of the initial
acceleration and confinement of the jet are uncertain. We apply an innovative
new model that allows us to determine key properties of the acceleration zone
via multi-frequency observations. The central component of the model is a
relativistic steady-state fluid flow, and the emission from physically distinct
regions can be seen to contribute to different energy bands in the overall
spectrum. By fitting with unprecedented accuracy to 42 simultaneous
multiwavelength blazar spectra we are able to constrain the location of the
brightest synchrotron emitting region, and show that there must be a linear
relation between the jet power and the radius of the brightest region of the
jet. We also find a correlation between the length of the accelerating region
and the maximum bulk Lorentz factor of the jet and find evidence for a bimodal
distribution of accretion rates in the blazar population. This allows us to put
constraints on the basic dynamical and structural properties of blazar jets and
to understand the underlying physical differences which result in the blazar
sequence.
