Black hole and cosmos with multiple horizons and multiple singularities
  in vector-tensor theories
  A stationary and spherically symmetric black hole (For example,
Reissner-Nordstrom black hole or Kerr-Newman black hole) has at most one
singularity and two horizons. One horizon is the outer event horizon and the
other is the inner Cauchy horizon. Can we construct static and spherically
symmetric black hole solutions with N horizons and M singularities? De Sitter
cosmos has only one apparent horizon. Can we construct cosmos solutions with N
horizons? In this article, we present the static and spherically symmetric
black hole and cosmos solutions with N horizons and M singularities in the
vector-tensor theories. Following these motivations, we also construct the
black hole solutions with a firewall. The deviation of these black hole
solutions from the usual ones can be potentially tested by future measurements
of gravitational waves.
