Observing substructure in circumstellar discs around massive young
  stellar objects
  Simulations of massive star formation predict the formation of discs with
significant substructure, such as spiral arms and clumps due to fragmentation.
Here we present a semi-analytic framework for producing synthetic observations
of discs with substructure, in order to determine their observability in
interferometric observations. Unlike post-processing of hydrodynamical models,
the speed inherent to our approach permits us to explore a large parameter
space of star and disc parameters, and thus constrain properties for real
observations. We compute synthetic dust continuum and molecular line
observations probing different disc masses, distances, inclinations, thermal
structures, dust distributions, and number and orientation of spirals and
fragments. With appropriate spatial and kinematic filtering applied, our models
predict that ALMA observations of massive YSOs at <5 kpc distances should
detect spirals in both gas and dust in strongly self-gravitating discs (i.e.
discs with up to two spiral arms and strong kinematic perturbations). Detecting
spirals will be possible in discs of arbitrary inclination, either by directly
spatially resolving them for more face-on discs (inclinations up to ~50
degrees), or through a kinematic signature otherwise. Clumps resulting from
disc fragmentation should be detectable in the continuum, if the clump is
sufficiently hotter than the surrounding disc material.
