The Relativistic Jet Dichotomy and the End of the Blazar Sequence
  Our understanding of the unification of jetted AGN has evolved greatly as jet
samples have increased in size. Here, based on the largest-ever sample of over
2000 well-sampled jet spectral energy distributions, we examine the synchrotron
peak frequency -- peak luminosity plane, and find little evidence for the
anti-correlation known as the blazar sequence. Instead, we find strong evidence
for a dichotomy in jets, between those associated with efficient or
`quasar-mode' accretion (strong/type II jets) and those associated with
inefficient accretion (weak/type I jets). Type II jets include those hosted by
high-excitation radio galaxies, flat-spectrum radio quasars (FSRQ), and most
low-frequency-peaked BL Lac objects. Type I jets include those hosted by
low-excitation radio galaxies and blazars with synchrotron peak frequency above
10^15 Hz (nearly all BL Lac objects). We have derived estimates of the total
jet power for over 1000 of our sources from low-frequency radio observations,
and find that the jet dichotomy does not correspond to a division in jet power.
Rather, type II jets are produced at all observed jet powers, down to the
lowest levels in our sample, while type I jets range from very low to
moderately high jet powers, with a clear upper bound at ~10^43 erg/s The range
of jet power in each class matches exactly what is expected for efficient
(i.e., a few to 100% Eddington) or inefficient (<0.5% Eddington) accretion onto
black holes ranging in mass from 10^7-10^9.5 M_sol.
