SIMBAD references

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 multifrequency 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.