Gravitational waves at the first post-Newtonian order with the Weyssenhoff fluid in Einstein–Cartan theory

The generation of gravitational waves from a post-Newtonian source endowed with a quantum spin, modeled by the Weyssenhoff fluid, is investigated in the context of Einstein–Cartan theory at the first post-Newtonian level by resorting to the Blanchet–Damour formalism. After having worked out the basic principles of the hydrodynamics in Einstein–Cartan framework, we study the Weyssenhoff fluid within the post-Newtonian approximation scheme. The complexity of the underlying dynamical equations suggests to employ a discrete description via the point-particle limit, a procedure which permits the analysis of inspiralling spinning compact binaries. We then provide a first application of our results by considering binary neutron star systems.