Superbubble dynamics in globular cluster infancy I. How do globular
  clusters first lose their cold gas?
  The picture of the early evolution of globular clusters has been
significantly revised in recent years. Current scenarios require at least two
generations of stars of which the first generation (1G), and therefore also the
protocluster cloud, has been much more massive than the currently predominating
second generation (2G). Fast gas expulsion is thought to unbind the majority of
the 1G stars. Gas expulsion is also mandatory to remove metal-enriched
supernova ejecta, which are not found in the 2G stars. It has long been thought
that the supernovae themselves are the agent of the gas expulsion, based on
crude energetics arguments. Here, we assume that gas expulsion happens via the
formation of a superbubble, and describe the kinematics by a thin-shell model.
We find that supernova- driven shells are destroyed by the Rayleigh-Taylor
instability before they reach escape speed for all but perhaps the least
massive and most extended clusters. More power is required to expel the gas,
which might plausibly be provided by a coherent onset of accretion onto the
stellar remnants. The resulting kpc-sized bubbles might be observable in
Faraday rotation maps with the planned Square Kilometre Array radio telescope
against polarised background radio lobes if a globular cluster would happen to
form in front of such a radio lobe.
