Are black holes in an ekpyrotic phase possible?
  The ekpyrotic phase (a slow contraction cosmic phase before the current
expansion phase) manages to solve the main problems of the standard cosmology
by means of a scalar field interpreted as a cosmic fluid in the Friedmann
equation. Moreover, this phase generates a nearly scale-invariant spectrum of
perturbations in agreement with the latest data. Then, the ekpyrotic mechanism
is a serious possibility to the inflationary model. In this work, by using the
approach of deforming metrics at linear level, we point out that it is
impossible to generate a black hole with spherical symmetry supported by an
isotropic fluid in this cosmological scenario.
