Uncovering the physics behind the blazar sequence using a realistic
  model for jet emission
  Blazar spectra are one of the most important windows into the physical
processes occurring along jets. The spectrum, composed from the different
emitting regions along the jet, allows us to constrain the physical conditions
in the jet. I present my work modelling blazar spectra using an extended
inhomogeneous jet model with an accelerating, magnetically dominated, parabolic
base transitioning to a slowly decelerating, conical section motivated by
observations, simulations and theory. We set the inner geometry of our
multi-zone model using observations of the jet in M87 which transitions from
parabolic to conical at 10^5 Schwarzschild radii. This model is able to
reproduce quiescent blazar spectra very well across all wavelengths (including
radio observations) for a sample of 42 BL Lacs and FSRQs.
  Using this inhomogeneous model we are able to constrain the location at which
the synchrotron emission is brightest in these jets by fitting to the optically
thick to thin synchrotron break. We find that the radius of the jet at which
the synchrotron emission is brightest (where the jet first approaches
equipartition) scales approximately linearly with the jet power. We also find a
correlation between the length of the accelerating, parabolic section of the
jet and the maximum bulk Lorentz factor. In agreement with previous work we
find that BL Lacs are low power blazars whereas FSRQs are high power blazars.
Together with our simple jet power-radius relation this leads us to a deeper
understanding of the physics underlying the blazar sequence.
