Hybrid stars in the light of the merging event GW170817

We study quark-hadron hybrid stars with sharp phase transitions assuming that phase conversions at the interface are slow. Hadronic matter is described by a set of equations of state (EoS) based on the chiral effective field theory and quark matter by a generic bag model. Due to slow conversions at the interface, there is an extended region of stable hybrid stars with central densities above the density of the maximum mass star. We explore systematically the role of the transition pressure and the energy-density jump Delta epsilon at the interface on some global properties of hybrid stars, such as the maximum mass, the last stable configuration, and tidal deformabilities. We find that for a given transition pressure, the radius of the last stable hybrid star decreases as Delta epsilon raises resulting in a larger extended branch of stable hybrid stars. Contrary to purely hadronic stars, the tidal deformability Lambda can be either a decreasing or an increasing function of the stellar mass M and for large values of the transition pressure has a very weak dependence on M. Finally, we analyze the tidal deformabilities Lambda(1) and Lambda(2) for a binary system with the same chirp mass as GW170817. In the scenario where at least one of the stars in the binary is hybrid, we find that models with low enough transition pressure are inside the 90% credible region of GW170817. However, these models have maximum masses below 2M(circle dot), in disagreement with observations. We also find that the LIGO/Virgo constrain (at 90% level) and the 2M(circle dot) requirement can be simultaneously fulfilled in a scenario where all hybrid configurations have masses larger than 1.6M(circle dot) and the hadronic EoS is not too stiff, such as several of our hybrid models involving a hadronic EoS of intermediate stiffness. In such scenario hybrid stars may exist in Nature but both objects in GW170817 were hadronic stars.