No Black Holes in NGC 6397
  Recently, \citet{vitral2021does} detected a central concentration of dark
objects in the core-collapsed globular cluster NGC 6397, which could be
interpreted as a subcluster of stellar-mass black holes. However, it is well
established theoretically that any significant number of black holes in the
cluster would provide strong dynamical heating and is fundamentally
inconsistent with this cluster's core-collapsed profile. Claims of
intermediate-mass black holes in core-collapsed clusters should similarly be
treated with suspicion, for reasons that have been understood theoretically for
many decades. Instead, the central dark population in NGC 6397 is exactly
accounted for by a compact subsystem of white dwarfs, as we demonstrate here by
inspection of a previously published model that provides a good fit to this
cluster. These central subclusters of heavy white dwarfs are in fact a generic
feature of core-collapsed clusters, while central black hole subclusters are
present in all {\em non\/}-collapsed clusters.
