Double-peaked Lines, Dual VLBI Components, and Precessing Jets in
  J1328+2751
  In this work, we report a radio galaxy with precessing jets, double-peaked
emission lines and the presence of two compact radio components with a
projected separation of ~6 parsec in Very Long Baseline Interferometry (VLBI)
observations. The emission line peak separations could be suggesting the
presence of a supermassive black hole binary (BBH) with a separation of 6.3
parsec, matching the VLBI results. The kinematic jet precession model applied
to the jets of J1328+2751 indicates that if it is a BBH, the accretion disk of
the primary black hole is not coplanar with the binary system orbit, making its
jet precess under the effect of the torque produced by the secondary black
hole. However, we find that the Bardeen-Petterson effect can also provide
precession timescales compatible with the jet precession period inferred in
this source. This source has previously been identified as a restarted
double-double radio galaxy (DDRG). Our findings therefore have important
ramifications for the nature of DDRGs in general.
