  Many extensions of the Standard Model predict new resonances decaying to a
$Z$, $W$, or Higgs boson and a photon. This paper presents a search for such
resonances produced in $pp$ collisions at $\sqrt{s} = 13$ $\mathrm{TeV}$ using
a dataset with an integrated luminosity of 36.1 fb$^{-1}$ collected by the
ATLAS detector at the Large Hadron Collider. The $Z/W/H$ bosons are identified
through their decays to hadrons. The data are found to be consistent with the
Standard Model expectation in the entire investigated mass range. Upper limits
are set on the production cross section times branching fraction for resonance
decays to $Z/W+\gamma$ in the mass range from 1.0 to 6.8 $\mathrm{TeV}$, and
for the first time into $H+\gamma$ in the mass range from 1.0 to 3.0
$\mathrm{TeV}$.
