Extended radio emission in MOJAVE Blazars: Challenges to Unification
  We present the results of a study on the 1.4 GHz kpc-scale radio emission in
the complete flux density limited MOJAVE sample, comprising 135 radio-loud
AGNs. While extended emission is detected in the majority of the sources, about
7% of the sources exhibit only radio core emission. Many BL Lacs exhibit
extended radio power and kpc-scale morphology typical of powerful FRII jets,
while a substantial number of quasars possess radio powers intermediate between
FRIs and FRIIs. This poses challenges to the simple radio-loud unified scheme,
which links BL Lacs to FRIs and quasars to FRIIs. We find a significant
correlation between extended radio emission and pc-scale jet speeds: the more
radio powerful sources possess faster jets. This indicates that the 1.4 GHz (or
low frequency) radio emission is indeed related to jet kinetic power. Various
properties such as extended radio power and apparent pc-scale jet speeds vary
smoothly between different blazar subclasses, suggesting that, at least in
terms of radio jet properties, the distinction between quasars and BL Lac
objects, at an emission-line equivalent width of 5 Angstrom is essentially an
arbitrary one. Based on the assumption that the extended radio luminosity is
affected by the kpc-scale environment, we define the ratio of extended radio
power to absolute optical magnitude as a proxy for environmental effects.
Trends with this parameter suggest that the pc-scale jet speeds and the
pc-to-kpc jet misalignments are not affected by the large-scale environment,
but are more likely to depend upon factors intrinsic to the AGN, or its local
pc-scale environment. We suggest that some of the extremely misaligned MOJAVE
blazar jets could be "hybrid" morphology sources, with an FRI jet on one side
and an FRII jet on the other. (Abridged)
