  Bright blazars were found to be prominent neutrino sources, and a number of
IceCube events were associated with them. Evaluating high-energy photon
emission of such blazars is crucial for better understanding of the processes
and regions where neutrinos are produced. Here, we focus on hard X-ray emission
observed by the SRG/ART-XC telescope, by the Swift/BAT imager, and by the
INTEGRAL/IBIS telescope. Their energy range ~10 keV is well-suited for probing
photons that potentially participate in neutrino production by interacting with
ultrarelativistic protons. We find that neutrino-associated blazars tend to
demonstrate remarkably strong X-ray emission compared to other VLBI blazars in
the sky. Both neutrinos and hard X-rays are found to come from blazars at
cosmological distances z ~ 1, and are boosted by relativistic beaming that
makes it possible to detect them on Earth. Our results suggest that neutrinos
are produced within compact blazar jets, with target X-ray photons emitted from
accelerated jet regions.
