Nonconservative unimodular gravity: Gravitational waves
  Unimodular gravity is characterized by an extra condition with respect to
General Relativity: the determinant of the metric is constant. This extra
condition leads to a more restricted class of invariance by coordinate
transformation. Even though, if the conservation of the energy-momentum tensor
is imposed in unimodular gravity, the General Relativity theory is recovered
with an additional integration constant which is associated to the cosmological
term $\Lambda$. However, if the energy-momentum tensor does not conserve
separately, a new geometric structure appears with potentially observational
signatures. In this text, we consider the evolution of gravitational waves in
the nonconservative unimodular gravity, showing how it differs from the usual
signatures in the standard model.
