  For the first time since the discovery of high-energy cosmic neutrinos by
IceCube, a multimessenger campaign identified a distant gamma ray blazar, TXS
0506+056, as the source of a high-energy neutrino. The extraordinary brightness
of the blazar despite its distance suggests that it may belong to a special
class of sources that produce cosmic rays. Moreover, over the last 10 years of
data, the high-energy neutrino flux from the source is dominated by a previous
neutrino flare in 2014, which implies that flaring sources strongly contribute
to the cosmic ray flux. We investigate the contribution of this subclass of
flaring blazars to the high-energy neutrino flux and examine its connection to
the very high energy cosmic ray observations. We also study the high energy
gamma ray emission accompanying the neutrino flare and show that the sources
must be more efficient neutrino than gamma ray emitters. This conclusion is
supported by the gamma-ray observations during the 2014 neutrino flare.
