  The MiniBooNE experiment reported results from the analysis of $\nu_e$ and
$\overline{\nu}_e$ appearance searches, which showed an excess of signal-like
events at low reconstructed neutrino energies with respect to the expected
background. A proposed explanation for this anomaly is based on the existence
of a heavy ($\sim 50$~MeV) sterile neutrino. These $\nu_h$ would be produced by
$\nu_\mu$ electromagnetic and neutral current interactions. A fraction of them
decays radiatively inside the detector. The emitted photon is misidentified as
an electron or positron in MiniBooNE. We have investigated the $\nu_h$
production by coherent and incoherent electroweak interactions at the MiniBooNE
and MicroBooNE targets, CH$_2$ and Ar, respectively. Studying the $\nu_h$
propagation inside the detector, we obtain the energy and angular distributions
of emitted photons for a choice of model parameters. The distinctive shape and
total number of photon events from this mechanism at MicroBooNE makes its
experimental investigation possible.
