A Blazar-Like Radio Flare in Mrk 231
  Radio monitoring of the broad absorption line quasar (BALQSO) Mrk 231 from
13.9 GHz to 17.6 GHz detected a strong flat spectrum flare. Even though BALQSOs
are typically weak radio sources, the 17.6 GHz flux density doubled in ~150
days, from ~135 mJy to ~270 mJy. It is demonstrated that the elapsed rise time
in the quasar rest frame and the relative magnitude of the flare is typical of
some of the stronger flares in blazars that are associated with the ejection of
discrete components on parsec scales. The decay of a similar flare was found in
a previous monitoring campaign at 22 GHz. We conclude that these flares are not
rare and indicate the likely ejection of a new radio component that can be
resolved from the core with Very Long Baseline Interferometry. The implication
is that Mrk 231 seems to be a quasar in which the physical mechanism that
produces the BAL wind is in tension with the emergence of a fledgling blazar.
