The relativistic parsec-scale jets of the blazars TXS 0506+056 and PKS
  0502+049 and their possible association with gamma-ray flares and neutrino
  production
  The physical nature of the mechanism responsible for the emission of
neutrinos in active galactic nuclei (AGN) has been matter of debate in the
literature, with relativistic jets of radio-loud AGNs as possible candidates to
be the sources of high energy neutrinos. The most prominent candidate so far is
the blazar TXS 0506+056, which is found to be associated with the neutrino
event IceCube-170922A. Furthermore, the IceCube reported an excess of neutrinos
towards TXS 0506+056 between September 2014 and March 2015, even though this
association needs additional investigation, considering the presence of a
nearby gamma-ray source, the quasar PKS 0502+049. Motivated by this, we studied
the parsec-scale structures of TXS 0506+056 and PKS 0502+049 through radio
interferometry at 8 and 15\,GHz. We identified twelve jet components in TXS
0506+056 and seven components in PKS 0502+049. The most reliable jet components
show superluminal speeds ranging from 9.5c to 66c in the case of TXS 0506+056,
and from 14.3c to 59c for PKS 0502+049, which were used to estimate a lower
(upper) limit for the Lorentz factor (jet viewing angle) for both sources. A
novel approach using simultaneously the brightness temperature of the core
region and the apparent speeds of the jet components allowed us to infer basic
jet parameters for TXS 0506+056 at distinct epochs. We also found that the
emergence of new jet components coincides with the occurrence of gamma-ray
flares. Interestingly, two of these coincidences in the case of PKS 0502+049
and one for TXS 0506+056 seems to be correlated with neutrino events detected
by the IceCube Observatory.
