  Observations of Gaia16apd revealed extremely luminous ultraviolet emission
among superluminous supernovae (SLSNe). Using radiation hydrodynamics
simulations we perform a comparison of UV light curves, color temperatures and
photospheric velocities between the most popular SLSN models: pair-instability
supernova, magnetar and interaction with circumstellar medium. We find that the
interaction model is the most promising to explain the extreme UV luminosity of
Gaia16apd. The differences in late-time UV emission and in color evolution
found between the models can be used to link an observed SLSN event to the most
appropriate model. Observations at UV wavelengths can be used to clarify the
nature of SLSNe and more attention should be paid to them in future follow-up
observations.
