  A strong nuclear kilomaser, W1, has been found in the nearby galaxy NGC 253,
associated with a forming super star cluster. Kilomasers could arise from the
accretion disc around supermassive stars (>10^3 Msun), hypothetical objects
that have been proposed as polluters responsible for the chemical peculiarities
in globular clusters. The supermassive stars would form via runaway collisions,
simultaneously with the cluster. Their discs are perturbed by stellar flybys,
inspiralling and colliding stars. This raises the question if an accretion disc
would at all be able to survive in such a dynamic environment and mase water
lines. We investigated what the predicted maser spectrum of such a disc would
look like using 2D hydrodynamic simulations and compared this to the W1
kilomaser. We derived model maser spectra from the simulations by using a
general maser model for appropriate disc temperatures. All our model discs
survived. The model maser spectra for the most destructive case for the
simulations of M = 1000 Msun are a reasonable match with the W1 kilomaser
spectrum in terms of scaling, flux values and some of the signal trends.
Details in the spectrum suggest that a star of a few 1000 Msun might fit even
better, with 10,000 Msun clearly giving too large velocities. Our
investigations thus support the hypothesis that kilomasers could pinpoint
supermassive stars.
